400-101 CCIE Routing and Switching 88 Frame Relay flv

[Music] it used to be a really big thing in the cci lab but these days it is there you need to know about it you cannot probably pass the lab without knowing frame relay but they're not going to be extremely detailed and they're not going to go very very very deep into it but still you need to know fundamentals you need to know a thing or two to actually be able to do it correctly and do it the right way so what am I going to do today is I'm going to use a very very simple network to demonstrate the the frame relay so this is going to be the network that I am going to be using today and also keep in mind that this is the network that you will be seeing many times throughout this week because I don't believe that you need to have an extremely complicated network setup an extremely complicated network design in order to demonstrate the behavior of protocols to demonstrate the things that that you are that you are working on you need to have three four five devices at most to be able to to be able to explore the technologies in-depth so for the frame line I'm going to be using just these three devices but because of the thing that I mentioned earlier that in your lab you are actually going to have one of your routers be the frame relay switch what we are going to do here in our setup is we are going to configure our five to be the frame relay switch so we are going to be configuring the frame relay switch and we are going to be configuring our r2 and r4 to be the endpoint devices before I can actually go in and talk about the endpoints talk about the frame relay and explore this in detail I need to clarify one thing that I have seen many of my students struggle with and it's a very very simple concept it's the concept of DT and DC now we all know that DTE stands for data termination equipment and that DC stands for data communications equipment now the problem here is that there are two unrelated things two unrelated concepts that use the same terminology and framerate is just one of them now on a fundamental level when we have two routers let's say our one connected to r2 and that are connected over the serial link one of these routers needs to provide the clocking needs to provide the speed so the side that actually provides the speed on layer 1 will be the DC the side that receives the speed that receives the clocking information from the link itself will be a DT and this is on player 1 now when we have a back-to-back connection like this when we have a router that is directly connected to the router the side that is DC is determined by the kind of the cable that is plugged in and it's a special side of the cable special connector that is called the DC connector and you can actually see this if you type show controllers serial interface the interface will tell you the router will tell you which side of the cable is actually plugged in here and again this is something to do with layer 1 now frame relay itself also uses the DC DT terminology and the frame relay switch on layer 2 is called the DC device while the end points are called DTS now it's important to understand that there is no relationship between this and this these are two completely separate concepts now the reason why I'm spending time talking about this is that I have seen students struggle with this idea when they would go into the lab and they would see for example that there is a requirement to configure r5 as the frame relay switch yet this device here is the serial DC and they would say but this is impossible decide this DC how can I make it a frame relay DT well you can because they are completely unrelated they do completely different things so as I said in layer 1 DC this is what happens now when we talk about frame relay and when we talk about DC DT they have a very very different function so let me talk about that just a little bit so I'm going to do one thing here now so again I have this network here and let's say that this is going to be our serial DC and this is going to be our serial DC which means that this side in both cases is the DT on these serial interfaces but because this is a frame light switch on frame light on layer 2 frame light switch is going to be acting as DC in both cases and these are going to be DTS so for frame relay functionality the function of DC is to respond to LMI inquiries by sending Ella my status responses now one thing to note about the DC is that it will never ever it never sends Ella my inquiry now the DTE side on the other hand and DT by the way is default on cisco routers it will send Ella my inquiries and it will never send Ella my status now this is important because I mentioned that you might have situation in which you need to troubleshoot the frame relay switch in the troubleshooting section of your lab and this is very very important because you can end up in the situation where this is causing some community not to work and you need to know where to look for it so what I'm going to do now is again let me just clone this page so all these examples here I'm keeping them so I'm starting with the fresh page that just has this background here so what I'm going to do now is just a very very simple configuration I'm going to bring these two interfaces up I'm not going to configure any IP addresses not going to configure frame relay to begin with I'm just going to bring the interfaces up and make sure that I get CDP neighbors so to verify that interfaces are actually fully operational so I'm going to go to a r5 going to say interface zero zero two zero no shutdown interface zero zero zero and I'm going to say no shutdown there on our two interface zero zero two zero no shut and on our four interface zero zero one zero no shutdown there so what I'm expecting here is that my interfaces have changed state to up so what I want to see is CDP neighbors and I can see that both r2 and r4 are now up and running so I do have the communication there so let me now change the link between r2 and r5 so this link here I am now going to change it to frame relay so the only thing that I'm going to do here and here is the encapsulation frame relay so no other changes so here I am on r5 encapsulation frame Here I am on r2 encapsulation frame so let's see what's going to happen here so if I do show interface serial 0 to 0 now for relatively brief period of time I will see that interface is up and the towline protocol is up but relatively quickly and I need to catch it there because it is going to take about 30 seconds 3040 seconds before we can actually notice the change here so let me not be too impatient and you know I already mention that I am very very patient and for very brief periods of time and of course whenever I want to reproduce some failure that takes much longer than ah there we go so here now we can see that on our to the interface change state to up and line protocol is down if I go to our five I'm going to have the same situation there but that's not exactly what I wanted to show you I wanted to show you one other brief situation so let me just bring the interface down very quickly I apologize for this just want to change the interface to admin down because up down is what you usually expect but there is one other state that is a little bit tricky to reproduce but it's very important to be able to see it at least once so that you know what you're dealing with just want to see something okay this one is sorry for producing so much output there but as I said sometimes it's rather tricky to reproduce these unusual transient States a PC may be our final because it no r5 does not have it oh my oh my oh my let me see I need to do a little bit more work to actually reproduce this problem so give me just one second here oh well I didn't change it to frame relay well that explains it silly me it works much better when you actually configure it to be what you need it to be so serial zero to zero what I have changed to frame relay is actually the wrong interface I have changed interface facing are for not r2 so now I have changed r2 to be correct so now I'm going to do now shutdown and this is the state that I wanted to show you so now you can see that the serial interface is up and line protocol is down and it says looped now I can guarantee you that this is the actual connection r2 here is connected to our file and you remember that when we hand this as hdl-c this was no problem we had the CDP neighbour and everything was functioning normally but now something on our to here is saying it's looped now what is looked this is where we have to go back to this rule here it says that the DC will respond to LMI inquiries by sending the LMI status and it will never ever send an element inquiry now earth to here our router r2 is configured to be DT it expects that the other side here is configured as the DC but in our case because we have we are using the default configuration on 0 0 to 0 and the default configuration here they are now both configure to be DTS which means that this router here is sending the LMI inquiries and this router here is sending LMI inquiries but our - here does not expect LMI inquiries back and here is when one more thing comes into play if I go to r5 and if I take a look at show interface serial 0 2 0 on r5 I'm going to see that the line protocol is down so r5 is not seeing this weird looped state but r2 here it's still saying it has looked and here is the key 1 the LMI enquiry so this is the inquiry that is being sent when the LMI enquiry is being sent out there is a serial number of it there is a sequence number that is being sent and let's say for the sake of simplicity that the sequence was number 1 now if when the interface came up on r2 if r2 was the one who sent the enquiry first r5 here configured as the DT is going to receive the inquiry from a router that it doesn't expect and what is it going to do it's going to ignore it because it doesn't expect it r5 on the other hand because it's a dickey sends its own inquiry and because interface came up first the second the sequence number is also going to be 1 so now our 2 is receiving an inquiry with sequence 1 and it assumes because it is sending the same inquiry that this is the same inquiry that for some reason was looped back now this is not true there was no loop here but this is what our two things is happening so when you see this situation here that you have that interface is up line protocol is down and it says looped and you are using an encapsulation frame relay you basically pretty much know right away what the problem is the problem is that on this link no routers are configured to be frame relay switches in other words none of the devices are configured to be DC devices now depending on the timing it could be one or the other in this case and this is why I said it might be a little bit difficult for me to reproduce well it turned out that the problem was that I was running encapsulation a encapsulation hdl-c so there was no LMI inquiry going on there but depending on which sense this inquiry first that will be decide that things is the looped one and it's usually going to be the one on the one that comes up last but the one that you type know shut down last on because that this is the one that will realize faster that the interface is up then the other side of the link and also it helps if it's a DC device serial DC which in my case it is so I can see that my serial zero to zero here is actually DC and you can see here that it's a v35 connector that we are using and that the speed is two megabits per second another telltale sign is clock rate two megabits on the interface you cannot enter this honest on a layer 1 VT side of the connection but as I said these are really irrelevant it's it was only the timing issue here in order to do that called r2 to have this looking it is because it realized that the link is up faster than the other side and it sent the LMI enquiry first so now we are stuck in this state that are two things that interface is looped and r5 correctly assumes that the line protocol is down mind you layer one is ok because the interface is up we are connected there is electricity there are keep lives well not really keep lives but there is a there is the AB the DC d signal that the carrier is up so that the bits are flowing back and forth and we are actually sending some data it is layer 2 where we have problem another thing that you can look at here so if we take a look at the interface here then this is on r2 we can see the two you're sending LMI inquiries we have sent 41 so far and we have received zero status responses here we have received 45 LMI inquiries and we have sent zero statuses now if you are sending LMI inquiries and we are received well that's a problem we have the same situation on our five here we have 29 inquiries sent and we have received 43 so this is the problem how do we address this problem well we need to turn our five into the frame relay switch so let's do that next so I'm going to again create a copy of this page going to go here and now what we need to do is we need to configure our r5 as the frame relay switch the configuration for that is very very simple so let's say just frame relay switch configuration these are the step first enable frame relay switching globally then create actually a there's one step between there so step number two would be make interfaces frame relay DC then create frame relay PDC connections now I call them PVCs because there are actually two ways to do that one is using so called frame routes and the other way of doing it is using connections I will show you both of these so these are pretty much the same they provide the same functionality except that the frame routes here are part of the frame relay switching framework and the connections are part of layer two sorry layer 2 VPN framework now this sounds scary I know that but don't worry these are actually much simpler to configure so that's what we are going to be doing next we are going to configure our r5 to be the frame relay switch which means that this one here needs to be the frame relay DC this one needs to be the framelit DC this one needs to be frame lady t and this one here needs to be frame lay DT so let's do that very very quickly I'm going to start on our five and only bring my text editor here and want to interface zero zero two zero encapsulation frame frame relay interface type DC really no need to bounce the interfaces but I always found the best results are when you actually do it and here before everything I'm just going to say frame relay switching this is where I'm going to enable frame relay switching so very very simple configuration so this goes on our five so now if I go back to our two if I take a look at my counters that should be happening relatively quickly now you can see here that we are sending LMI inquiries so here we have we have sent 67 and take a look now we are actually receiving a status in response here is the second one and take a look we are no longer looped now it's a line protocol is down take some time for this to come in it will take for actually three of the statuses for this to work so there is the the third status received and we can see here in the middle of this output that line protocol actually changed state two up and we can see now that we have that this counter is increasing but we are no longer receiving the frame relay inquiries we are only receiving the statuses on our file joint phase serial zero to zero oops we are now sending the statuses but this counter here is no longer increasing this one stays at 54 and we can see that this one increased from 5 to 6 so now we actually have frame relay connection between r2 and r5 r5 is acting at the switch and we should have the same situation with our 4 except on our 4 we haven't configured the frame relay so on this is still hdl-c so let's configure it as frame when we do that we should be receiving the inquiry at some point there it is one enquiry has been received and as I say it takes some time for it to come back up and there we go it just came up so now we actually have frame relay connectivity between r2 and r5 and our 5 in our for now we know no not yet have the connection between r2 and r4 what we're going to do now is we are going to make the connection between r2 and r4 so our our 5 is the frame relay switch so that doesn't change so what we want to do is let's have a black connection between r2 and r4 so on this black connection I want to used LC 2 0 4 on r2 and I want to do used LC 402 on our 4 and I want to have 192 168 24 0/24 as the IP addressing on this connection and I will use dot - on r2 and I will use 4 on r4 s the IP address now the requirements for this connection here and I will write them down so this is going to be the black one is that I want to use on both sides on r2 and r4 I want to use frame relay physical interfaces which means I'm not going to be using any sub interfaces and I want inverse ARP to be turned off now inverse ARP is an address resolution protocol that works on frame relay so let me just briefly give an introduction to what inverse ARP does and we are going to see it in action as well later on but for now I want it to turn off so let's first take a look at how ARP works just a regular ARP now just basics networking 101 the CCNA lecture for free so what we have here is let's say that we have host a and host B that are connected to a common switch now when a wants to communicate with B and let's say that a has an IP address for beam let's said it's 10 10 10 10 so let's say that a has for some reason has the IP address of B in its ARP table and sorry it has the IP address it knows the IP address of it but it doesn't know what is the MAC address of B so what it can do is it can send the broadcast here asking who has 10 10 10 10 now the switch here being the switch and let's say that there are some other connections on the switch when it receives this single packet here it's going to actually replicate and flood this broadcast out to all interfaces except the interface on which it was received and eventually be here will receive receive this broadcast packet now this is how ARP works and for this to work what we are relying on is the broadcast replication in the cloud where our cloud here is actually just a single switch or we might have multiple switches now the reason why this works why this is so simple is because Ethernet is multi access network with broadcast capability now frame relay on the other hand is non broadcast network which means it's a multi access non broadcast network which means we cannot do this we cannot send a single packet to a frame relay switch and tell it or sorry I should say single frame to a frame relay switch and tell it hey send this to everyone you know about we cannot do that so what inverse ARP does is something very very different so let's here take a look at the inverse art what we have here again let's say that we have host a we have host B and here let's say that we have some switch and we are connected here so this is now frame relay switch and let's say that we have some house C now on this link here frame light switch is going to communicate to a what are the available deltas and let's say that the available deltas are the connection to C and the connection to B and let's say that this is these are Dells is 102 and 103 so what a here can do is it can send out a request down the LC 102 and down del C 103 basically saying hi I'm a sorry and ask who are you now the same question a is going to ask of B except this is happening over another del C now one thing that I want you to take a look at is this part hi I'm a inverse ARP is a very polite protocol it is always going to introduce you are itself now this hi I'm a is actually a message hello this is my IP address what is your IP address now being a polite protocol if you are always going to get a response from inverse ARP so see here will always respond back saying oops sorry wrong color it's always going to respond back saying okay I'm C and B here is always going to respond with I'm B now when you talk about inverse art it's important to understand that we can turn off the question but you cannot turn off the answer that means that the router if it receives the inverse ARP request it will always respond to it why because it's a polite route it's a polite protocol when you are polite when someone says hello you answer hello it hurts nothing right except in frame relay it can actually hurt because if the lab says make sure that you don't have any dynamic mappings in your network basically they want you to turn off the inverse art please make sure that you turn it off everywhere because if you forget just one place just one place the very fact that you have received the question will create a dynamic mapping on this router here you know not only need to send the question and get the response because when someone tells you unsolicited hi my name is Marco you immediately know their name same thing here inverse ARP will learn the remote IP address if it hears the question so when we say that inverse ARP needs to be turned off it needs to be turned off on both sides of the connection for it to make sense and I will demonstrate to you right now so the first thing that we are going to do is we have already configured interfaces on our file here to be DC interfaces so what we need to do is we need to configure these oops sorry about that just apologies what we need to do now is we actually need to create the tell C's so this tells E 204 I need to create it on r5 on this interface and on this one I need to create tell C 204 and I actually need to create the cross connect between them I need to create the PVC so let me go to my terminal and I'm going to start on our 5 as I said there are two ways of doing this one is using the old frame route the that use the frame relay switching framework and the other is slightly newer using the Kinect commands I will show you both but first let's do the traditional frame relay switching I really remember that I have enabled it but it doesn't hurt to do it again let me actually do this from the the text editor so the first thing that I'm going to do is in my text editor I'm going to say frame route under the interface delcie 204 needs to go out of the interface serial 0 0 0 as del c 402 now for this to work I actually need to create a return route on the destination interface so basically what I need to do is these two commands but let me first show you how it looks when you configure just one side so now I'm going to say show frame route and we can see here that the input interface is serial 0 2 0 interface input del Z is 204 the output interface is serial 0 0 0 and the output del Z is 4 0 2 and it says status inactive and doesn't matter how long I actually stay here the status will always show me inactive because it is expecting the route back so now when I add the route back relatively quickly it's going to take maybe 20-30 seconds for it to start changing the status there we go it already change the status now we can see that both of these Delta's are now actually in active state so if I go to R 2 for example if I do show frame PVC I will see now that I have Delta 204 that is unused so nothing is actually using this del C and its own interface serial 0 to 0 if I go to our 4 and if I do show frame PVC I see on serial 0 1 0 I see del C 402 again its unused but its active because the frame relay switch told us about it so what I'm going to do next is this is the configuration of our 2 serial 0 2 0 interface so what I'm going to do now is I'm going to shut this interface down I'm going to configure IP address 192 168 0 2 actually was was it zero to that I wanted to use luckily it let me use 0 2 here instead of 24 to so so this is going to be 0 let me correct it maybe I have this one here as well okay that was the only place where I had it apologies about that so and I'm going to do the same thing on our form so I'm going to say IP address at the down IP address one of two 168 0 4 and now on our two I'm going to say no frame relay inverse art so on art - I'm turning off the inverse R if I take a look at the configuration this is how the interface looks on our 2 and on our for this is how interface looks there so let me show them side by side so this is on art for and as you can see I have not touched the inverse R P R which means it's turned on and on our to the inverse arp is actually turned off let me bring up both of those interfaces so if i do show frame PVC now i can see that the del c is there del C says still unused it's going to say that for just brief time there we go we have this on our for now let me go to our - ok let's wait for some time it actually it takes about 60 seconds for this to happen so we might need to wait just a little bit again my patience kicks in and in the meantime I am seeing a question why is it so simple when you explain it it took me some time to configure my frame relay switch at home or I did answer that question before it's always difficult when you're doing something for the first time right it is the practice that is going to make it appear very very easy and as I said I've seen astronauts fly the space shuttle so many times you put me behind those controls and you would have me in the news very very quickly the same thing here when you are configuring something for the first time of course it's going to be difficult it's supposed to be difficult we don't want anyone being network engineer the way so then when you practice it when you do it once or twice or in my case 81 times it becomes a little bit easier as the time goes by now this is at this moment starting to confuse me a little bit because it should have worked by now so let me troubleshoot this a little bit what have I done wrong so just going to take a look at the configurations here 1 2 0 2 that's ok so run interface serial 0 1 0 the hats okay and show friend round am I getting any input packets okay now actually this was a telltale sign for me that it actually worked the way I expected it it just we just needed to wait a little bit now take a look at this so now I'm looking at layer 3 to layer 2 map on r2 and what I'm seeing here is that IP 192 168 0 for R 4 easily reachable over Delta 2 0 4 and this is a dynamically learned entry this is inverse ARP now take a look it has input packet 1 that means this doesn't tell me how many frames are received from the switch no this tells me how many del sees how many packets I received over this del see how many packets I received end-to-end so I knew here I expected to see from our 4 hello I am our four who are you and by virtue of actually receiving that question I have a dynamic entry now if I go to our 4 and if I do show frame map here I'm going to see that I have a dynamic entry so have they actually satisfied the requirements of this task is my inverse arp off no it is not it is actually running on this tell see even though i was under the impression that I turned it off so this is why I was warning you if you are instructed to turn off the inverse are you need to make sure to turn it off on all the devices that are connected to your frame relay cloud and in this case this these are r2 and r4 so let's go and fix this problem so on our for now on serial 0 1 0 I'm going to say no frame relay inverse ARP but my problem actually persists because this dynamic little earned entry is not going to be so easy to unlearn yeah I'm no longer going to be asking any questions but you know the entries that I've learned they stay I have to clear them so you can do that with clear frame in our oops type up so now when I do show frame map I no longer have that map in there and the same thing on our too so if I do clear frame in ARP now I no longer have the dynamic mapping in my layer 3 to layer 2 database so at this moment I also do not have the communication between r2 and r4 if I cannot use the dynamic dynamic mappings I need to use the static mappings so let's add some static frame maps to our configuration so what I'm going to do here is I'm going to say frame map I want to map an IP address 192 168 0 for 2 del C 204 and on the other side I want to do something in the opposite direction so frame map IP 1 to 168 0 to 4 0 2 so now if I take a look on our to show frame map what I'm seeing here is that I have a static mapping this is the the framing end-to-end framing it can be either Cisco or it can be IETF but in this version of code in this version of iOS the difference is really academic because the iOS will try to how to detect what framing you're using so even if you set something else it doesn't really matter again as I say this used to be a big thing earlier in earlier versions of the lab for version 4 blueprint this is irrelevant thing so I'd see that this is a defined mapping and it's active so right now from our for I should be able to ping are sorry from our - I should be able to ping are 4 and I can see 5 exclamation marks and as my wife says I'm the happiest when I see those exclamation marks in the lab so if I ping from our 4 to our - I'm also getting the exclamation mark so this is good now my question to you is and I am hoping to hear answer so get ready to do some typing can i from our 4 ping r4 can I ping 192 168 0 4 from our 4 that's very good the overwhelming answer that I received is no let's just confirm that well helps with do obviously I cannot pink now the next question is going to be crucial why why is it that I cannot ping from our 4 to our 4 now mind you here I'm not asking you how to solve this problem what I'm asking you is why can I not pink what's the reason for this ping not working I'm smiling because the overwhelming answer that I received is exactly what I expected you all know how to fix it you all know that I need to add the brain mapping and one of the answers was it's the way frame relay works it needs to be mapped to the layer 2 to layer 3 resolution and one was the loop prevention that's not actually it but you have not answered my question you are telling me how to fix it but what's the problem why I mean it's my own IP address why should I not be able to pin it if I take a look here for example on our 4 if I do for example show IP safe I will see that 192 168 0 4 is set to receive on serial 0 1 0 why can I'm simply not pink myself while you're thinking about that I'm going to stop the video because I want to prepare one example there so unrelated to this and I just want to show you something totally different example I'm going to have two routers this is going to be r6 and this is going to be our 9 this is serial 0 2 0 this is serial 0 2 0 and the network between them is 192 168 69 0/24 this is dot 6 this is dot 9 and we are running default hdl-c encapsulation between them so let me bring these two routers in and if I take a look at the interface show interface serials ero 2-0 on our six I can see that this is 1 & 2 2 1 68 69 . 6/24 and on our line show interface serial to 0 it says 100 to 1 68 69 9/24 and we can see here that encapsulation is hdl-c so there is no frame relay involved nothing of the source my question is if I ping 192 168 69 9 from r6 will this work very simple yes no what do you think yes of course it's going to work now another question is if I try to ping myself 182 1 68 69 6 will this work yes no very good so this works like a charm let's go to r9 so on our line I'm going to pink 69 6 will this work what do you think again yes no ok very good and this works like a charm pink 192 168 69 9 will this work again simply years now oops help me troubleshoot this a little bit so our six can ping our 9 + r6 can ping r6 our 9 can ping our 6 but our line cannot ping our 9 again hdl-c interfaces on both sides so no frame relay involved where would you start troubleshooting this problem show run interface on our line well that's of course the very logical place to start so show run interface serials arrow to serum that's pretty much what I have IP address and no fair - so would you like to see the other side on our six okay so there is the configuration of the interface on our six do you maybe see something that something that sticks up well yeah but why would an access list on our six affect the traffic when our nine pins are nine well let's see what happens when our six tries to ping our six so obviously I know that works but what happens if I actually do a trace rat now mind you this is my own IP address take a look at the trace wrap it actually goes out to our line when it gets routed back to our six now when we have serial interfaces and all serial interfaces on all Cisco routers operate in the same way there is a serial interface and we are perceiving it as one interface when actually there are and I am oversimplifying things here there are actually two circuits one is the transmit circuit and the other one is the received circuit now the transmit circuit obviously sends the traffic out and the received circuit receives the traffic there is no shortcut between transmit and receive inside the interface so if we want to do self thing instead of sending the traffic here to interface and somehow it being returned inside the interface what actually needs to happen is this traffic needs to go out of the interface and on the remote side either looped back or actually routed back so that we can receive it on the receive side of our circuit now this has something to do with the implementation of serial interfaces on Cisco devices nothing to do with frame relay now this is what you will encounter mostly on frame relay but there you had an example with hdl-c where we had an access list on our six preventing the ping from our nine to our line if I do show access list here what I'm seeing in the access list is a deny statement that denies the ICMP echo traffic from our nine to our nine so if I do a trace route from our nine so instead of just thinking if I do trace route I can see it going to our six and then coming back to our hand actually that this was a very good example because trace route in iOS is not ICMP so this will actually succeed but we can see where this traffic goes but if I was to change this access list just a little bit so IP access list extended 100 no 10 and if I said deny pypy this so just deny oops denies IP like this show access list so now I'm just going to be blocking all IP traffic not only ICMP so now if I do trace route I can see it going to 69 six and that is where the traffic is being dropped now mind you this is as I said a serial interface hdl-c no frame relay involved now that same exact thing is actually happening in our frame rate example so what needs to happen here and let me bring this in what needs to happen here is when I try to ping from r4 to r4 what I need to do is I actually somehow need to send the traffic for 192 168 0 4 out of this interface send it down this cross connect to r2 then r2 is going to route back to response or actually route back that same traffic so that I can receive it on our for when I'm responding to my own ping I'm actually sending the response out of this interface where it gets routed back when it gets switched and then it arrives back now the problem here is of course in this part and this is something that you have correctly identified you all knew how to fix it because serial zero one zero is a multi-point interface what is happening is we know where to route the packets that's no big deal because we actually have the route so if I do show IP route on our 4 I can see that 192 168 0 0 slash 24 is pointing out of serial interface but let's take a look at what happens when we actually send the traffic there so what I'm going to do here I'm going to create a very simple access list 100 permit ICMP any-any echo so I this is the only thing that I care about and I'm going to say debug IP packet 100 ok so I'm going to watch for traffic that is ICMP echo traffic and I'm going to pin one into two 168 0 4 and I'm going to send only one packet so let's see what our debug tell now the first thing that we are going to see here that the packet is actually being routed there is no problem with that then we can see that we are actually generating the traffic we are sending the packet down the accept encapsulation path so we are at layer 3 we do have the route we know where to send the traffic and we need to send it down the layer to layer 2 so that we can actually generate the frame to send and this is where the operation fails we have encapsulation failed encapsulation failed means that we do not have layer 3 to layer 2 mapping we know where to send the packet that's not that's not a big deal the routing table tells us that but we don't know where to send the frame so this is why if you want to provide for self ping in frame relay you actually need to have a mapping it's the combination of the serial requirements and it's the combination of the requirements that on a multi-point frame relay you actually need to give it a del C to send this traffic in and it all stems from the same fact that there is no that shortcut inside the circuit where you can actually send the traffic now I should clarify this there is actually an ability to configure this shortcut but it cannot be selective you can configure it only for all traffic and the command to do that is to actually enable the loopback on the interface so here are 4 you would say interface serial 0 1 0 you would say loopback and when you enter this all the traffic that arrives in on transmit will actually be sent out or the other way around anything that you try to send out you will be receiving back so it basically creates kind of a you loop to you loop kind of sends all the traffic out and everything comes in from the inside sends back but you cannot send the traffic out of the interface and selectively return it back it's all or nothing so this is actually a very bad command to configure unless you are testing something in production environments and I am guessing that in 2013 nobody's testing anything on Syria lines it would be very very unlikely that that you are involved with that but if you are that is a useful so in order to actually fix this and this is what all of you knew the answer for is we need a frame relay map statement so I'm going to go to our four interface serial zero one zero and I'm going to say frame map IP one to 168 0 4 and I'm going to map it to del C 402 so if I do show frame map now I will have the map for the remote IP address and I will have the map for the local IP address which is something that I can ping and look at how much debug output I've received so what I'm going to do next is I'm going to send just one thing again to see what happens here take a look now here we have the output that says the traffic was routed out to the routing table we are generating the frame we can generate the frame it goes out but take a look at this now we have actually received the frame so this is the source this is the destination we are receiving it it's being routed we are receiving the traffic and we are stopping the processing of the packet there it is not going down the encapsulation process because this is packet for us so we are now punting it up the routing engine for processing up the routing processor so this is really the root cause why you need that one single map statement for self ping and not necessarily related to frame relay because you've seen it with the hdl-c the next thing here between r2 and r4 and mind you let's do the same let's apply the same fix on our two so that r2 can ping itself if I was to run a routing protocol between r2 and r4 let's say rip or eigrp or OSPF would I be able to do that without any additional modifications well I believe that we briefly mentioned it yesterday as somebody was asking me about the broadcast statement on the frame line and I went explaining it in in the chat so I'm now going to do it here as well right now the broadcast traffic or the multicast traffic between r2 and r4 does not work and I can easily verify that if I think the broadcast address from our to take a look this traffic is actually failing to go out if I try it from our for where we actually have the debug going on so 1 2 2 1 6 th 0 2 4 5 repeat 1 I will see pretty much the same thing as I've seen before it says ok this is a broadcast or multicast packet there from frame relay perspective treat it the same way and it says encapsulation failed the reason for this is that the frame relay is non broadcast media that means it does not support broadcast traffic which is slightly misleading statement what frame relay does not allow me to do is it will not replicate the traffic for me so let's say this is a frame layer switch and I have two nodes connected let's say three nodes connected to it so this is a B and C what I cannot do is send a single frame to a frame relay switch and then have frame relay switch actually replicate this frame to these two for me this cannot be done in frame relay but what I can do in frame length is I can do the replication for myself because frame relay ultimately doesn't care what kind of traffic you are sending so what I can do is I can send traffic to C and I can send another copy of traffic to B now frame relay switch doesn't care what's in the IP destinations of this traffic so this could be IP multicast or this could be IP broadcast traffic or ipv6 multicast traffic from frame relays perspective these are all unicast frames it was a red frame that was sent to C and it was a blue frame that was actually sent to B now obviously because I am doing the replication here the bandwidth on this interface becomes an issue because instead of sending just a single frame out there and have the switch fan it out switch replicated for me I actually have to do sudo broadcast replication for my sells so it's not that the frame relay network does not support multicast or broadcast traffic it does it just won't replicate it for you but we can send unique or we can send multicast or broadcast traffic obviously the way to configure that and let's do it on our four first would be to add the broadcast keyword on either one of these statements so just to add to the confusion I'm going to add it on this statement here now one of the very very common misconceptions that I have with my students is that this is an incorrect configuration because if we take a look this is our four and I'm configuring the broadcast for our fours IP address at least that's the perception of what I have done but this is actually not relevant because this broadcast keyword here is the parameter of the Delsea and the protocol so this command line actually the way it is perceived by our router is this oh I cannot delete that so let me uh let me get creative here for a second and of course that didn't quite work the way I wanted you to work but I'm not giving up just yet so basically the way this is perceived by the rudder is this the router doesn't care what the IP address is the only thing it cares is that for IP protocol on the LC 402 enable sudo broadcast replication now another thing that you might have here is instead of IP you could have ipv6 in which case you are enabling through the broadcast application for ipv6 and those of you who might be going for a service provider test later on another option that you might have here is CL NS which is needed if you want to run is is over the frame relay so this is why this IP address is irrelevant and why this is a perfectly valid configuration here so let's give it a test so I'm now going to paint 192 168 0 255 repeat one from our four and now what I will see is that the packet was actually sent and I have received our response so there is the response from 192 168 0 2 you see that 0 2 actually responded to this traffic now on are two obvious ly this doesn't work just yet because on our - I have not enabled through the broadcast replication so let's go ahead and fix that on our - again it doesn't matter on which entry you do that so let's do 182 let's try pin here so now we should be seeing this traffic going out and on our 4 you're actually going to see some debug output because this was now a code traffic not a curry spy another common mistake about the broadcast statement that I see from my students is the following one because they are unsure about this do I do I need it here do I need it there sometimes just to make sure my students do this so now I have enabled pseudo broadcast replication on two of my del shield on two of my frame map statements but keep in mind that they are referring to the same del Z so let me again send just one thing just one pink goes out so we can see it here that one packet was sent and take a look at this we have received two responses from our two because this thing here is actually aligned to us one packet indeed was sent but it doesn't tell us how many frames were sent this one packet actually got encoded in two frames and were sent as basically copy of the same traffic was sent twice to our two and our two responded to from what it perceived to pink packets but we can see here that they were actually the same ping packet because it was request number zero if I send multiple requests what I'm going to see now is two packets go out and you can see here that I'm receiving responses to requests zero and here there is an echo request response to request one the time receiving so this configuration that we have now in place is something that I would highly recommend not doing so try to avoid having broadcast statement entered twice so this now is more correct configuration so this is the right thing to do not the one with to broadcast statements we are going to add another link between r2 and r4 and let's call this one a red link so we're going to add a link here and let's make this one two one four and four one two on this side and this will be 192 168 1 0 / 24 and for this one so let me write down the requirements for this we are going to use the frame line multi-point sub-interface and we want to have inverse arp on for this furthermore for this example here what I'm going to do is I'm not going to be using the frame route I'm going to use the new connects tables to get this cross-connect working so for this part here instead of using the connect state instead of using the the frame maps I'm going to take the del C 204 here and map it to Delta 402 here and back using the connect statements or as I like to call it the new way of configuring frame relay switch so let me go to the terminal and I'm going to go to our file here and I will need my notepad as well now for this new way of configuring frame relate connection instead of starting in an interface configuration mode you basically start in the global configuration mode and all you have to do is simply say connect and actually I'll do it India in the terminal so that I can show you with the question mark so you simply say connect and the first thing that you need to enter here is the name of the connection this can be anything but I'm going to call it R 4 sorry R 2 - are 4-1 and the next thing that we say is let magic we have side a and side B or segment a and segment B segment one segment to call it whatever you want to call it so one segment will be this connection here between R 2 and R 5 so basically this interface on our five and the other segment is this segment here and that means this interface here on our five so basically what I need here is to name that segment to specify which interface so let's say that segment number one in my case here is going to be the DC segment one and let's say that this is segment two here so what I'm going to do is I'm going to say that cereal 0 2 0 and del C 2 1 4 on it our segment 1 and then I specified the segment number 2 which is going to be cereal 0 0 0 and del C 4 1 2 when I press ENTER I am entering the configuration mode for this connection and you don't need any options here the only conceivable one that you will ever want to use here would be shut down everything else applies when you are using this in combination with for example MPLS layer 2 VPNs or l2tp version 3 which are the topics that are not covered by the CCI routing and switching exam they are covered on the CCIE service provider but since you are not studying for service provider you don't have to worry about it so we are basically done here so I'm just going to press ctrl C and exit from this configuration mode so the only thing that I have now in the global configuration mode is this and if I do show frame route this command or this new connection will not show up because it's not part of the frame relay switching framework which is what show frame route is telling me but what I can see is if I type show connection all I will see this connection and you can see here that we have the identifier we have the name so identifier is just a random number that will I get assigned second choice would be 1 2 3 4 5 etc then we have the name which is the name that we've given it we have segment number one here which is serial 0 2 0 2 1 4 we have segment 2 0 0 0 0 4 1 2 and we can see that the state is up now please keep in mind that I did have some client Rob here these two equal signs are actually part of this long line but I guess that someone in Cisco didn't actually count very well so this is very wide output for unknown reasons but this is what we have now the important thing to notice here is that if I do show frame route I have this old configs in place and I have the new one so they can coexist if I go to r2 and if I do show friend PVC what I'm going to see here now are two PVCs one is to 0 for T R 1 is to 1 for which is okay this is exactly what I mean it I have created a new delta T so from R 2 and our force perspective there is really no difference between using the old command and using the new command it's only what happens inside the box on our 5 that is slightly different so this is again the new way of configuring yeah frame the frame relay switch and this basically ends my presentation on the frame relay switch itself because these are all the commands you need to know frame routes frame relay interface type DC you need to know how to create the frame routes and you need to know how to create this connect statements so that's frame relay switch so from now on I'm just not going to be focusing too much on the frame switch 1 I need new Delta I'll just create it but we have to continue with our task so what I need to do here is I need to create a multi-point sub-interface on r2 so here I need to create sub interface I'm going to call it 1 and here I need to create sub interface and it needs to be multi-point on both sides so let's do that next so I'm going to go to our to actually I'm going to first bring in Maya not bad so I'm going to say interface 0 0 to 0.1 alt point and IP address 1 to 168 1 2 to 5 0 so this goes to a r2 on our for what I need to do is just slightly change the IP address here paste the same so if I go to r2 and if I do show IP route connected this is what I'm seeing now I see that 192 168 1 0 slash 24 is directly connected on serial 0 to 0.1 on our 4 for the show IP route connected to show IP when in doubt slow down to show IP route connected so what I have here now is 192 168 1 0 slash 24 so I do have the route so if I try to ping between r2 and r4 will my pink actually work the overwhelming answer was yes that I should be able to ping but let's give it a go so I'm here on r4 and I'm going to say pink 182 168 one two and when I send the pink I'm getting encapsulation failed so the thing is actually failing right now so turn off the debug and let's take a look at why my ping is failing so again I'm still on our 4 I'm going to say show frame PVC now this is the PVC that I actually care about for one to take a look to which interface is this PVC map - it's mapped to a physical interface serial 0 1 0 so if I take a look at the running config of the interface and the sub interface I'm mapping the interface that the del c412 to this interface here but there are no tells is mapped to this sub interface so when I try to ping I do have the route but I don't know where to send this traffic I don't have any dlc map there so how do I bring in the del C to my serial zero 10.1 and the same thing is on our - what do we need to do to make this work you know the time setting you up for a trap when I ask seemingly simple question so again the over going answer that I received was you need to create the frame map well let's read the requirements again this needs to be a frame relating multi-point sub interface that's okay but I need to have inverse or on now the problem with inverse are on is that it's incompatible with frame Maps so when I use the frame map on a particular del C basically I'm going to turn off inverse or on that tell see I need a way to map a Dell C 2 a sub interface that does not involve the frame map statement do I have such an option well as it turns out I do have it the option to do that is frame relay interface del C command now the problem again that I've see seen many students struggle with is that there is this assumption that frame relay interface del C command is somehow related to point-to-point sub interfaces well in a way it is related to point-to-point sub interfaces because this is where you are most likely going to see this command but when you are running frame relay with a multi-point sub interface you can still use this command because the only thing that this command says is that this del C is available on this sub interface and that's exactly what I need to do I just need to tell my router r2 here that del C 2 1 4 is actually available on a sub interface and not on the main interface then what's going to kick in is the inverse ARP which is going to help me provide my layer 3 to layer 2 resolution so let's go end up take a look at this so I'm going to go to r2 now and I'm going to save frame relay interface del C 2 1 4 now if I do show that I'm going to type exit here when you show frame PVC now I will see that del C 2 1 4 is now mapped to serial 0 2 0.1 now on our for show frame PVC still shows the old output now I might need to wait around a minute to show you something but it may have already happened so what I'm going to do now is this it actually already happened take a look at this now you remember that in our previous task we have actually turned off an inverse arp on serial zero one zero but take a look at the highlighted entry it's a dynamic mapping on a physical interface serial zero one zero take a look at the IP address here it's 192 168 1 2 so our four things that this IP address is available on this physical interface even though our inverse arp is actually turned off here how did this happen well as it turns out when you create a multi-point sub interface which we do have on r2 so when we created this interface here and when we actually map the Delsea to it inverse arp started working on this interface and contrary to popular belief the inverse arp statement configured on a physical interface is not inherited on the multi-point sub interface so this configuration here or I should say this configuration here does not apply to the sub interface so r2 is actually sending out inverse ARP requests and remember how they look hello I am are - this is my IP address what is your IP address when r4 received it it created that dynamic mapping and responded to r2 which also has a dynamic mapping but it has actually a correct mapping because on r2 del C 2 1 4 is actually mapped to a sub interface but on our 4 it is not yet mapped see here del C 4 1 2 is actually mapped to a serial interface this is yet another thing that you need to be on a lookout for with inverse ARP you see how dangerous it can be in the lab when this can cost you two to lose points not only that but you are now cross wiring the traffic now the traffic from a physical interface on r4 is ending up on a sub interface on r2 some of the traffic is ending up there now you can see also here that the broadcast traffic is actually mapped to this del C which is the default with inverse art which means that if I send for exam Oh SPF hellos or AIGA pillows or rip updates they would be actually arriving on our to sub interface from a physical interface on our for extremely dangerous and not to mention it can be very annoying because in a case of voice PF you're going to get a log message that is going to be popping up every now and then and I wouldn't be surprised if some of you in the lab that you are working on right now have this exact same situation because we actually have this in a couple of our labs so what I'm going to do now is I'm going to fix and correct this issue luckily it's very easily corrected all I have to do on our four is actually create a sub interface which I've already done and say frame late interface tell c412 now with that configuration so show friend till you see what I've done is I have remapped the Delsea from a physical interface to a sub interface and also when I've done that the dynamic mapping is now gone so we now have to wait for inverse ARP to do its magic and it's going to take around 60 seconds for it to do that unless we speed it up and the easiest way to speed it up will be to actually bounce the interface but we do have 60 seconds to wait so let's give it a little weight and if that doesn't help we are just going to up wait a little bit and by the way you can see now that our - actually has an incorrect mapping so let me just clear that and let's wait for a magic to happen you can observe inverse off so it literally just happened I believe oh no no not quite yet so we need to our will it wait a little bit so that's okay you can observe the inverse ARP operations the command is debug frame events this will actually show you the inverse ARP requests so as they go in or go out so maybe we can just give it a little bit of a nudge there sometimes sending the traffic yelps Oh No well I would hate to do this but looks like it's going to be the fastest way to do it not enough time - uh - wait hold a four in reserved WA comes to its senses so not yet there we are seeing inactive here is first have to wait for the switch to send us the information there we go now we have the mapping NAR for we can actually see that this actually happened here we got the inverse ARP we received it and we actually responded to it so here I have on serial zero to 0.1 now I have the correct mapping and I should be able to ping r4 on our fore side let me turn off the D bugs show frame map I should have the correct mapping for r2 and I should be able to pin it also please note that when you are using inverse ARP the pseudo broadcast is automatically turned on for you so there is nothing you need to do to make that work but when you are using inverse ARP you have the problem with self pink this will not work and the bad news is that when you are using inverse ARP and you are required to use only inverse ARP there is no way to make this work because the way to make this work would be to configure the frame map statement and if in the lab they tell you don't use frame app statements well don't use frame app statements you just have to live with the fact that you will not be able to ping your own interface don't fall for the time waster that involves creating a loopback interface with an IP address and then on a multi-point interface using IP unnumbered because this is what will happen in that case so I'm just going to show you that example so I'm just going to say IP unnumbered loopback syrup take a look it says this is available or this is possible only on non multi axis interfaces so you cannot do this on a multi-point sub interface so let me see if this actually up remove the configuration it did not remove the IP address which is good so I should still be able to ping the other side so to recap if you are asked to use in furs are without the frame map statements forget about the self bang that will not work and this is something that is perfectly acceptable in the lab if this is what they actually want you to do the question is some of my frame interfaces that transit through frame relay switch only come up when I have no keepalive command now I find it very unlikely and here's the reason why because the kno keepalive command what it actually does it turns off the LMI on the frame relay so going back to a an example that we had before or the similar example to network this is similar to example that we had before so I'm going to reuse our six and are nine you may remember them from the hdl-c self pinging example before so what I've done is I have removed that one access place that was preventing the traffic and I have also removed all the configurations from the interfaces into connecting our six and our nine so here we have zero two zero interfaces so let's say that I wanted to have between our six and are nine I wanted to have two logical connections I wanted to have a blue del C and red del C so let's say that this is going to be six oh nine on this side and six oh nine on this side and that the red one is going to be nine zero six and nine zero six and that I want to run let's say 192 168 ninety-six 0/24 here and that I wanted to run 192 168 sixty-nine 0/24 here again six nine on two other sides so I have one interface and I want to have two logical connections between these two devices now there are two ways I can solve this but let's just blindly go ahead and configure this so what I'm going to do now is I'm going to configure interface serial zero to zero on both sides to be frame relay and I'm going to create a sub interface here so let's say this is going to be 69 interface point-to-point type IP address 1 to 1 68 69 6 just correct the typo that I had there and the other one is going to be 96 like so and let's map the delcie so frame lay interface delcie 609 here and they'll see 9:06 here and finally let's do no shutdown so this would be the configuration on our 6 and on our line basically what I need to change is this to 9 so if I go to our 9 and paste this in what's going to happen here is the interface is going to change they to down it's going to change they to up but if I do show interface 0 0 to 0 here remember this it's going to show up as looped why is it showing up as loop because we are sending the inquiries and we are receiving the inquiries on our line here we are seeing up and down so I don't have the frame relay switch here this is something that is called back to back frame relay now when you have this configuration here this is where we basically on this interface here and on this interface here we need to do no keep alive now when we do this no kippa live here basically what we are going to say is we are turning off the LMI so there will be no inquiries therefore there will be no loop so this is one solution for this another one would be to declare one of these interfaces as the DC even though we don't have the frame relay switch so if I go back might configuration here so in actually I need the the text editors let me bring it up so what I'm going to do here is I'm just going to say no keep alive that's the only change so this goes to r9 this goes to our six so now if I do show interface serial zero to zero when the interface actually comes up I will see here you see it says encapsulation frame relay look back not set keep alive not set which means we are not sending any any lmin queries and you see remember that all state owes about the LMI enquiry Santelli my inquiries received the statuses that's all gone because right now we are not actually using any LM I if I do show IP route I'm going to see those two routes and I can in fact ping the other side so if I do ping $16.99 I can ping the other side and if I try to ping 96 nine I can ping the other side so this is where these these are the most common situations when you would have to enable no keep alive but mind you one more thing there is actually a situation that is similar to what you described and that is that sometimes when you're going to the frame light switch you need to do it so let's say here that you had a frame with light switch so this is a frame relay switch and you have router r1 and you have router r2 now if you have mistakenly configured this interface here as the frame relay DC using frame relay interface type DC command in that case you would actually have to turn off the keep lives why because you are sending the status here and you are never ever going to send the inquiry which means that this guy he will never receive an inquiry from you and it will bring the interface down you on the other hand are expecting to receive the inquiry from the frame relay switch which you will never receive therefore you are going to bring your interface down so if for whatever reason you have mistakenly configured as the frame relay DC in that case you need to configure no keep alive another situation in which you may run in is if on this side here you are using let's say Cisco as the LM I type and on this side you for whatever reason decided to use an see there is going to be a discrepancy here which again is going to cause the interface to go down on this side if you use no keep live on both sides of this connection the frame relay switch n on your router you're going to maintain the appearance of this connection being up when in fact it's it's semi up because you will not have situation the frameless which cannot now communicate which tells is are actually active on your connection it might have some active Delta's but it cannot tell you that because you are turning off the LMI these are the two examples that we went through so far so we have built the black del Z between r2 and r4 and we have built the red Delsea let's add green del see here and this green del see here is going to be two to four ups sorry Bella it is going to be two to four on this side and it's going to be four to two on this side the IP addressing scheme is going to be 192 168 to 0/24 and here are the requirements and this is going to be very very very easy straightforward we are going to use frame relay point-to-point sub interface and there is no inverse ARP to worry about when you are using a point-to-point sub interfaces there is no inverse art so let's start this configuration by going to our r5 actually let me bring my r5 there it is so going to our five and where we have that connect statement so this is pretty much the same thing I have to do so I'm just going to paste it in this is going to be r2 r4 connection number two two two four going to four two two just confirming that it actually got created there it is and on our to what I should be seeing show frame relay PVC okay not just yet I was a little bit faster than iOS there we go delcie two to four is now available but keep in mind it is available on serial zero to zero by default so I have to move it to a sub interface so let's do that I'm going to go to interface serials ero to zero going to create the sub interface number two I'm going to say point to point I'm going to say IP address 192 168 to two and then I'm going to say frame layer interface type also interface del C 2 2 4 and this is going to be the error message that is going to meet me now it says that PVC is already assigned to interface serial 0 to 0 in this version of iOS in the version of iOS that you will have in the lab this is an unknowing situation that you will encounter when you are creating a point-to-point sub interface for a del C that is already mapped to a physical interface there will be this error message there are multiple ways of actually solving this some are more intrusive than the others but one that I found works the best is to actually go to a physical interface and do no frame length interface del C 2 2 4 so on a physical interface I am telling the rudder delete this del C from the interface so now if I do show frame relay PVC I will see ok sorry about that I will see that this interface is actually gone from the mapping but there is a problem with that that is that this command that I just entered is not actually in the in configuration it does take effect so delcie was actually removed but you've seen here on the output that I did just prior to the one that I said was okay that LC was present now the reason why it was present is that every what is it three or four LMI inquiries the router is going to request a full status update when that happens the router is going to relearn the Delsea that you just removed so unless you have already mapped it to a sub interface in the meantime after some period of time that LC oops I just removed I was hoping that damn yeah they will be able to show you this oh there it is actually it just showed up I was very lucky so here the Delsea showed up even though I have actually removed it from the interface so you might be unlucky that you type in this command so you want now it's removed from interface then you go to a sub interface and then when you type frame relay interface tells you actually I can just do it like this you get that error message again well this pair not just remove it from the interface and do it again or even better just do this in one single copy/paste action so you just go to interface serial zero to zero say no frame interface del C 2 to 4 then go to the sub interface mode and create it so you take this copy paste and if you get the error message you know that PVC is present you just paste this couple of times now if you're trying to delete the del C that doesn't exist the router will complain but do you really care about the router complaining I don't so let's do the same thing on our 4 so there it is his interface 1 and this is Del C 4 to 2 and we need an IP address so we're going to our 4 so here we're going to ups going to paste this in we got no error messages there so show frame PVC what I'm looking for is for two two mapped to a sub interface which it is and on our two here show frame PVC on our two I'm looking at Delta 2 2 4 is mapped to a sub interface which it is sure I threw out connected shows me that this subnet is pointing to a sub interface so I should be able to ping our 4 I should also be able to ping myself now the reason why I can ping myself with no additional action is if I take a look at the show frame map and for this Delta here you see that no actual IP addresses are mapped to Adel see it just says this is a point-to-point del see now so let me take a look at the configuration of the interface here when we declare a sub interface as point to point we are telling the router you are going to have one and only one del C available on this sub interface now sub interfaces are perceived by upper layer protocols as individual interfaces which means no matter which traffic I need to send out of this interface there is only one way out and this is this interface is it going to be a ping to a remote side is it going to be pink to my own IP address or is it going to be broadcast traffic it doesn't matter it all goes out because this is a point-to-point Delsea point-to-point else's are by far the easiest configuration that you may encounter in the CCI lab because they behave in a way in just exactly the same way as point-to-point interfaces don't like PPP or hdl-c now usual warning is that if something looks to be very very simple technology wise it's unlikely to be encountered in the lab for point-to-point sub interfaces the situation is the exact opposite in these days in the lab point-to-point interfaces are most likely to be seen in the lab everything else you need to be on a lookout for you need to be aware of it but it is not very likely to be encountered in the lab so basically past hour hour and a half I have wasted your time not really you still need to be on a lookout for it it could be in the troubleshooting question it could still be in the configuration section you could be asked to configure it let's build blue delcie and the blued LLC again it's going to be between r2 and r4 so it's going to be two again I make the same mistake so it's going to be two three four on this side and four three two on this side and the IP addressing is 192 168 three 0/24 now this is going to be a little bit trickier so on this side I'm going to have slightly different setup on r2 and r4 so on our two side I want to use point-to-point sub interface and on this side I want to use multi-point sub-interface now I want r2 to authenticate are for using mschap version two and I want our four oops I want our four to authenticate r2 using it so what do I need to do here does frame relay support any authentication by default there is no authentication in frame relay and if you want to do authentication in frame relay we actually have to run PPP over frame relay and then anything that PPP support frame relay will support so let's start by building this PVC between r2 and r4 so I'm going to go to my r5 well to create the new connection again very very simple stuff there we go I'm just going to confirm it exists and then I'm going to prepare the configurations that I'm going to be needing here so I'm star I'm going to start with our two sides so interface serial zero to zero I'm going to say no frame relay interface Dulce two three four then I need to create sub interface and my memory gives me up here to I need to I need point-to-point sub-interface yes it's point-to-point so this is going to be interface dot three point to point and here I'm going to say frame relay interface del C two three four PPP and here I have to specify I'm going to need a little bit more space I'm going to specify the virtual template to you so let's just use virtual template 24 okay that's it I don't have to configure anything else on the sub interface now I have to configure the virtual template itself so virtual template 24 again remember what I told you earlier I know the encapsulation is PPP by default but I'm not going to trust iOS about it I'm going to set its text me exactly point 25 of a second to do that 250 milliseconds so the next thing that I have to do is see who's authenticating who are two needs to authenticate are for using mschap version two so what I need to do here is really first create the username for our--for I'm just going to use our for s username and password IP expert and I'm going to say PPP authentication mschap version 2 now I also know that our four will be asking for my credentials using EEP so let's give it that answer so I'm going to say PPP identity r2 PPP sorry PPP eat identity and PPP eat password IP expert so this is the configuration on our two now this is going to be the considerate on our four I'm going to put them one above the other just so uh you can let me see if I can fit them both somehow probably can there we go this will work so I'm going to paste this in now the configuration on our four I'm expecting the username from our two this changes this changes this changes this changes to multi-point this changes actually what I'm missing here is an IP address so let's add the IP addresses here and Here I am expecting it and I need to have to respond with chap now the problem is when you are using EEP as authentication and you know consistency of iOS there are 10 commandments of iOS commandment number one thou shalt not be consistent and these were the ten commandments of iOS so when you're using EEP as the authentication you are expected to use radius if you're not using radius and you actually want to use the local database which is what we want to do you actually need to tell the router to use local database so we need to tell it PPP EEP local so let's start with our tools configuration let me switch to r2 so this is the configuration on r2 and on our for this will be the configuration so I'm going to paste it in and when I'm done with that I should be seen that interface virtual access has changed state 2 up so if I do show IP route connected take a look just like with regular PPP I do have two routes in the routing table one is slash 24 which I configured and the other one is the IP address for the neighbor I can ping the neighbor but I cannot bring myself to the same situation is on r2 right now so if I do show IP route connected I can ping 4 but I cannot ping my own IP address if you want to provide for self pink in this scenario here what we would need to do is create a loopback interface and then on this interface virtual template instead of setting the IP address you would say IP unnumbered that loopback interface so I'm going to do that just on our for just for just for fun so I'm going to say interface virtual template 24 i PR numbered look back for and then I'm going to create interface look back for and I'm going to say IP address like so so if I do show IP route connected now this is what I'm seeing and this is where that flashed early to route may start making some sense take a look at this now my slash 24 is reachable through the loopback now if this was the only route that I actually had in my routing table I would never be able to ping our two from our four why because I would be sending traffic out of the loopback interface but now when PPP over frame relay is actually up and running and when I learned slash started to route from the neighbor I know that that particular host is actually reachable through that virtual access interface and not through my loop back so at this point I can ping my neighbor from r4 but I can also ping myself because this traffic here is going out of the frame relay interface well it's actually going through the virtual access interface which is then going over the frame relay enriches our to but this traffic is actually going out of the loopback interface so I have two different destinations for this traffic so this is one of the reasons why we have that / 32 route the one that I talked about when I talked about PPP itself so as far as I'm concerned this is as complicated as frame relay can get in the lab now of course there are more topics that are related to frame relay like QoS configuration on the frame relay and interaction of frame relay with routing protocols but these are the topics that I'm going to cover when I talk about the queues and when I talk about those individual routing protocols

Channel: Networking Lessons

Views: 569

Keywords: configrouter.com, Cisco, Cisco Networking Videos, Cisco Networking

Id: GJEkwYvEFnM

Length: 106min 30sec (6390 seconds)

Published: Thu Oct 12 2017