15 AP Radio and WLAN Configuration in the WLC PART 1

[Music] okay so for our next section and really continuing on in the we'll see or wireless LAN controller graphical interface we're now going to begin on the wireless tab so we've already gone over how helpful help can be we've looked at the commands looked at management skipped security we're coming back we've gone to the controller we're now going to and we've briefly looked at the monitor we're going to go to our wireless and then our W lands tab and then we will be going back you know once we've set up our AP radios and the wireless lands that are going to propagate and radiate out over those radios then we'll be going back and monitoring after we actually you know fire up a client and begin some of the actual association of a client the whole point of this exercise to the radios so we're on the wireless tab and we can see that I have four of my five ApS because one is in autonomous mode and I've named them sales support floor one AP one two and three and sales support floor to AP two and we can see the model so I've got a 1252 a G and 1131 a G a 1262 n which also does a B G and N and a light weight access point or cap table 3502 P okay and this really the P actually has in this case to do with the 3500 the fact that this one has external antenna capability versus the 3502 n that has internal internal antennas so I've got two ABG n radios and I've got two ABG radios they can't do n we also see the AP MAC address now what MAC address is this and before we move on let's just talk about MAC addresses on an access point for a moment because there's a number of them and they can be confusing we've already talked about them but I just want to make sure everyone's clear on this so we have to begin with we always have if we say the MAC address of the AP we may be referring to and in this case it is the MAC address of the ethernet let's actually go ahead and pull up our switch over here so if I take a look let's see if I can actually have both side by side I'm not sure if we'll be able to have everything that I want here yeah I think we can kind of manage so I have my APs okay and I've got the MAC addresses over here I can see that actually let's go ahead and do a show power in line I think we had them on ports FA 0 11 and 12 let's just look at FA 0 11 and 12 let's do a show MAC address table or interface fast 0 11 and 12 okay so here's my MAC address 7 0 Charlie alpha 9 Bravo 1 5 4 alpha Charlie echo and then I've got the Mac 4 port 12 as well if I take a look at this Mac let's just look at the last four it ends in 4 alpha Charlie echo or 4 ace here is that MAC address right here for alpha Charlie echo that's my 3502 it's on port 11 and I was also able to tell that by my show power in line that it was my I'm sorry not 3511 3502 on port 11 go back up to those show MAC address interface and got 13 echo alpha that's my 1262 those are my 2n radios on port 11 and 12 so the AP MAC address is clearly the Ethernet MAC address okay and if we back on the switch we had looked earlier I'll just expand this out so it's a little clearer show IP if I did show IP dhcp binding we had seen that for alpha Charlie echo or ending in for alpha Charlie echo is this MAC address it's on VLAN 210 and it had gotten an IP address in VLAN 210 okay so back on the wireless LAN controller the AP MAC address here under Wireless is clearly the Ethernet MAC address when we were back on the monitor tab and I had gone to access point summary and clicked on all AP's we had actually that is the same one if I had clicked on one of the particular radios then we had seen base radio Mac so the base radio Mac is going to be different than if I just go back to monitor all ap okay so for my 3502 my AP mac that's my Ethernet MAC address or media access control address if I go back to monitor and look at my let's say a n radio 4 we don't actually see the radio model so we have to reference it by the floor name let's just go back and look at all APs and my 3502 is named floor 1 AP 1 so floor 1 AP 1 we're gonna go back and look at a n so for floor 1 AP 1 I have a base radio mac that ends in 6 Delta 7 zero not for Ace or AC e if I go back and look at what was that Mac again it was six Delta seven echo I'm sorry six Delta seven zero if I go back and look at my BGN floor one AP also has six Delta seven echo okay so there's a base radio MAC address even though those are two separate radios and then we're going to have a new so that's the that's basically the bssid is going to be the base SSID MAC address but now as I create later different wireless LANs they're each going to have a different MAC address the MB or multiple basic service set identifier okay so the MB SSID will be the MAC address that's a new newly created MAC address for each radio for each SSID so let's go back to wireless I just wanted to make sure that everyone's clear on what MAC address is assigned where and we can see how long these aps have been up whether they're enabled we can also click on these right now we happen to be on access points all APs we can click on any one of these ApS let's just look at our let's say let's look at our 3500 to our most capable we can see that we could change our administration status to disabled we see the AP MAC address which is our Ethernet MAC we also see the base radio Mac it's called the base because we're going to create derivatives of this MAC address for the various well actually we're not going to the AP will dynamically create those mbss IDs we don't really need to know what those mbss IDs are to much if we want to we're gonna basically throw up a sniffer a wireless LAN wireless network controller on a laptop in when I say network controller I should say a wireless interface on a laptop or smart device or whatever infamous qeh smote and put a packet capture utility like arrow peak or you know we're gonna use Wireshark here we talked about the different modes that access points can be deployed in here's where we set that they can be local mode they can be H reap mode which we talked about the new I'm running 700 code here in 7.2 code and I believe the test is on 7.0 but the new code 7.2 actually calls this flex Connect okay you could also refer to it as H reap office extend so if someone refers to office extend this is what they're talking about we can run monitor mode to sit there and just listen we can run rogue detector where we effectively shut off our radio and just listen on the wire in that particular Senate e for other rogue ApS we can turn it to sniffer note mode where we can basically connect our arrow peek or Wireshark or something to a remote antenna and listen there and again all traffic is going to be cap whopping encrypted back to the will see and will listen or really gather and download our pcap files our packet capture files from there we can turn it into bridge mode this is what we're gonna use for a mesh network and we can also turn it to something called se connect what is se Connect se Connect is for spectrum analyzer expert so there is actually a product called spectrum expert it's basically a spectrum analyzer cisco acquired this particular product from used to be called air magnet basically but acquired this product and it is a very powerful spectrum analyzer it goes way beyond just a toe 2.11 networks and it can analyze other for an and accurately identify other types of traffic such as Bluetooth radios wireless analog video cameras microwave ovens radar microwave transmission not microwave oven but but you know high-powered building antenna microwave transmissions that are not in the 802 11 spec it can accurately identify these in a lot of other things inverted wireless signals things that get into very deep wireless theory and basically things that will interfere with your network so we already talked about something called briefly we talked about something called Cisco clean air and how the thirty five and thirty six hundred series of ApS can detect these very same types of information the reason that they can do that is because they actually have a separate silicon chip on their access point that doesn't really take any processing power away from the CPU it's independent and it's I it is outside of the range of just standard 802 11 specification it is a true silicon based spectrum analyzer it's listening to radio waves and able to accurately identify what the types of traffic in those given ranges are based on signatures you know based on the frequencies based on their duty cycles based on all sorts of different factors that create a wireless signature not only can we do this on the 3500 I and 3600 series of access points but Cisco also sells the spectrum expert client for a Windows laptop and we're not going to be taking a look at it the actual client here in the CCNA Wireless I could throw it up real quick just to give you a brief look at it but we're not going to really go into it at all we do look at it in depth and it's required knowledge to know that product inside now for the CCNP Wireless site survey exam but one of the things that we can do with that client is we can act we connect the client and I should go back and say when we fire up this client on our Windows laptop we have to have a Cisco specific access point caught on the access point but a Cisco specific card or we can connect remotely to an access point and that's what this mode is se connect we can use spectrum expert to connect to this wireless card I've started to this wireless access point and use that as our sniffing card and the reason we might want to do that is actually when we buy the license for spectrum expert we typically and historically before this thirty five hundred and thirty six hundred ap came out we bought a very custom wireless network card from Cisco as a PCMCIA card with newer laptops we just had to have a PCMCIA to USB adapter that would that had that very same on chip or on board silicon chip that was a spectrum analyzer you know specific card or specific chip and ASIC and the wireless card was very expensive not to mention the fact that I might want to use spectrum expert on my Windows laptop and look at various different parts of my wireless network in different cities or maybe even different countries and so I can connect over the existing infrastructure that we have existing local and wide area network to a will see a wireless LAN controller and therefore connect to one of these APs that's a 3,500 or 3600 in SE connect mode if I go back and I grab one of these other APs I don't have se connect mode and the reason is it doesn't have the onboard silicon processor and it's a very easy thing to know can I use se Connect can I use this ap as a spectrum expert spectrum analyzer basically to connect to the answer is if it supports clean air if the AP supports clean air then it will also support this SE Connect mode okay and that is the 3,500 and the 3600 series currently on the exam you might only see 3500 series because the 3600 series might have and I believe it did come out slightly after the publishing of the newer exam or at least after the writing of that exam keep in mind sometimes when you're taking a Cisco exam you'll have to keep in mind that sometimes the exam came out in at a certain date and you might know more or there might be newer products than or even technologies like we said flex connect versus H reap then what was available at the writing of the exam and since they only refresh the they typically refresh the network associate na and network professional NP exams roughly every I would say 18 to 24 months so about every year and a half to two years and the CCIE exams they refresh about every two to three years on a window of about 24 to 36 months sometimes a little longer sometimes a little shoulder shorter but you have to remember that when you're taking these associate and professional exams sometimes newer code base or newer products have already come out so just and and you might say well then how do I know how to answer a question on an exam just look at all the possible answers and choose the best possible answer so if you see you know of all these you know maybe a question says written below are all of the current Cisco access points on the market and you might look and you might say no it's not there's newer access points than that then just yeah and then it goes on to say choose the access points that support Cisco clean air technology and the 3500 is there but the 3600 is not there choose the best answer in that case there would be only one correct answer it be the 3500 okay so just keep that in mind when you're taking exams anyway it's going to tell us about this eight the primary software version if it has a backup software version loaded if it's already downloaded newer software that has come out maybe we updated our controller or wireless LAN controller and the AP has gone ahead and pre-downloaded the newer software but it hasn't actually gone through a reboot yet so it's not really running that yet what's the bootloader version of software what's the iOS software and what's the mini iOS okay what's the difference here well the bootloader is the hopefully you understand what a bootloader is but this is basically a small piece of code that is used just to get the access point or whatever device router switch whatever it is we're looking at to boot up and it boots up into its iOS software which is 12 for 23 C J a for the Mini iOS version this is what corresponds to the firmware that was downloaded from the wireless LAN controller so this is really kind of a a nice way of saying hey if I'm at 7.0 on my AP then I'm in sync with my wireless LAN controller which is also running 7.0 code okay what the access point is really running is this iOS version 12.4 23 C so remember whenever an AP boots up before it actually downloads its configuration it's going to upgrade or possibly downgrade to a parody version of or with the wireless LAN controller and from the wireless LAN controller we see we have an IP address it was not obtained via static configuration it was obtained through DHCP we know that because the static is not ticked if it was we could configure it change things if we wanted to we also can clear the config except for the static IP if we set a static IP and hit apply we can clear all config we can just perform a hardware that doesn't clear any config but you know just resets it or restarts it clearing the config basically sends it back to factory default this sends it to factory except for the static IP okay we're not gonna look too much at credentials right now let's take a look at interfaces we've got our Ethernet interface and we've got our radio interfaces we have one Ethernet interface interface zero gig zero it's up how many unicast it's transmitted received how many non unicast like multicast and broadcast its transmitted and received we can click on this to get more detailed statistics framedrops CRC errors giants runs all that good information that we care about in typical Ethernet environments also is it at 100 full for speed and duplex respectively then we can take and by the way CDP we have ticked it's supported on the ethernet by default CDP or cisco discovery protocol is not ticked or or supported on the wireless radio 0 and radio 1 radio 0 slot 0 is the BGN so this is the 2.4 gigahertz radio radio 1 is the a n this is the 5 gigahertz radio it's not on those we can turn one or both on so radio zeros 2.4 radio one is 5 gigahertz we can also see that the this radio is enabled it's operational status is up and because this was our 3500 the clean-air administrative status is up and it's actually operationally up clean air is down by default i've already enabled it and we'll take a look at where we can enable it when we come to it high availability we talked about the idea of a primary controller let's go ahead and enter our primary controller IP address whoops that is the name let's put in will c1 and the management IP maybe we would have will c2 and another management IP maybe be like 10.2 dot 1.21 and what's the failover priority hey if the wireless LAN controller isn't available how quickly or how important is it that we failover let's go back into our 3502 I should go back to high availability I hit apply but wasn't really done with all the tabs yet let's make sure did I change the mode no good by the way if I'm in local mode or monitor mode I have the ability of a sub mode which is the wireless eye intrusion protection system we're not going to enable that now but if I was concerned about security and I wanted to deal with that I could do that there inventory just tells me the product ID version ID of the product serial number ok what is it it's a Cisco ap it's a wireless access point there's a manufacturer installed certificate and H Reap remote office access is supported we're not going to go into all the things on the Advanced tab we can take a look at our regulatory domains country code us is the only thing available because if I go down here to country I only have United States checked maybe I wanted to do United States and I don't know let's say United Kingdom ok and it's gonna say that radio resource management channels and power levels are limited to common channels and power levels when I have multiple country configurations two common channels so basically whatever the lowest common denominator is our am I sure that I want to have multiple countries selected if mesh ApS are connected please remove them or use a single country configuration since mesh ApS do not support multiple countries typically we're only going to want one country so I can select multiple countries but there's rarely a time when that makes sense to do so because typically an access point is not in multiple country maybe I might have an access point on the border of two countries and maybe I do need to maybe it's like US and Canada I might need to do something like that but for right now the country code configured is only us if I configured another one let's go back into our 3502 ap then I could choose the different country code and that would give me different regulatory domains and it would also give me different configuration abilities or parameters or attributes that I could configure for different power levels antennas things like that I can give it a little bit more information about P Oh II am I using p8 o 2.3 AF which is power over ethernet am i using pre standard switch such as Cisco inline power okay so the the 3500 actually I should say even the 35 50 was inline power not POA the 35 60 and 37 50 and 65 hundreds have p OE power over ethernet that's the standard but if this might be inline power so I might want to click that I might be getting power from a power injector so that is to say I have I have a cable coming from the switch and then before it gets to the AP I plug a power injector into that cable and I also plug it into the wall which introduces a direct current or DC voltage up to 15 point 4 watts into the actual cable or it possibly even more just depends on the power injector power injector cube 1 2 3 etc if that's going to or if that's gonna inject power into the ethernet cable before it then gets to the actual access point and therefore powers the access point so I can deal with things like that is the power injector installed what's injector switch MAC address information like that we had talked about the maximum segment size and really the MTU being like 2300 louver 2356 I think it was exactly but might be a little off there of a wireless frame an 802 11 frame and how about was a lot bigger than a 802 dot 3 e3 at frame standard 1500 megabit or sorry 1500 bytes unless we're using anything like giant or jumbo frames in Ethernet I might have I might have more data put in the wireless payload and therefore have to fragment back at my Ethernet switch or mice which would fragment for me if it didn't support the Ethernet size the jumbo frame it might not even just depends on the multi-layer switch capabilities it might not even forward it so I can do a TCP adjust MSS this is something we can do on most every router and it's got a default value of 13 63 taking into account the wireless headers that are gonna be added and the fact that Wireless headers are a lot larger than Ethernet headers so it's basically saying the data payload should only be 13 63 and TCP adjust maximum segment size is going to inform clients that are sending TCP layer 4 type IP packets on that they can't stuff more than that much data in their UDP packets typically aren't that big TCP packets a lot of times are so we can do that but this is on the individual radio we're going to see in here just a moment that we actually have global configuration with global configuration we have the ability to set certain attributes TCP adjust MSS being one of them globally for all radios and it's not necessarily a bad thing to do it all something I tend to do so that we don't have jumbo frames or giant frames that are being sent into the switched infrastructure and having to deal with fragmentation issues okay am i able to SSH or telnet directly to the device does this ap support rogue ap detection I can also group access points together there is a default group by default we have the ability to actually group ApS together and we'll be taking a look at that in a little bit we can create multiple different AP groups and then you know use those to collectively assign attributes to them versus one at a time or versus just globally okay so let's go ahead and click we can also add a location so maybe I say Mark snows office and this might get included in traps and syslog whoops can't use that ' okay so we've looked at one radio we've pretty much looked at all of them it's just that not all of them support se connect mode not all of them support clean air so we've looked at the all ApS now let's go look at the individual radios for the five gigahertz a N and the 2.4 gigahertz BGN so as I look at these I begin to see the ApS their base radio mac operational status what channel they're on doesn't really look like I can do a whole lot here ok now if I go to the BGN wait a n have something over to the right sorry I thought it did over on I was hoping that this would resize but it doesn't dynamically resize so it doesn't look like I can do a whole lot here until I scroll over is what I meant to say as I go over I can see that I can click or not really click but just mouse over anyone these radios and notice that three of these radios have configure details and information about TSM we really won't come to much to that in this particular module but then one of the radios has clean air radio resource management let's just take a look at let's say my a p2 which is an N radio and actually let's go back and I meant to first click on detail where we just get a lot of information about the particular access point so we get the bssid we haven't done anything with MBSs ids yet because we haven't even created wireless lands or any SS IDs yet we just have the the root B SSID we have operation rates whether they're supported or mandatory so 6000 kilobits or 6 megabit is mandatory 9 is supported this is sort of giving us a summary of what is configured on this particular access point and more importantly not just on the access point but on this particular radio because for the access point we have two radios for really each of these ApS so let's go back and let's take a look let me go back to all ApS I just want to make sure I'm looking at the right one the 1262 is for one a p2 good let's go back to let's just look at BGN to begin with and we were looking at a and earlier so let's look at a P let's look at floor 1 AP 2 which is our 1260 to n radio operating on channel 6 notice the little asterisks that means it's been globally assigned so there's not a specific channel configured on manually or individually for this particular radio it's been globally assigned so let's click on configure we can enable individual radios just like we can enable an entire access point we can enable or disable one of the radios maybe I want I you know almost every radio or almost every access point that you're gonna buy today is a BGN so it has dual radios 2.4 and 5 gigahertz radios and with that being said maybe I want to disable the 2.4 gigahertz spectrum altogether now we'll talk later about when that might not be possible with things like mesh networks but let's just say it's a standard deployment and I want to use only 5 gigahertz because I'm going to be I'm gonna be setting up an environment where I know all of my clients have 5 gigahertz capabilities and that's an important thing to make sure of not all clients do and I'm gonna be setting up in an environment where there's a lot of noise a lot of other ApS like I showed you that I have here in my office building and I only want to transmit on the 5 gigahertz spectrum so I could disable the ABG I'm sorry the BG n basically the 2.4 gigahertz spectrum I'm gonna leave it up for right now with 802 11 N first of all is it supported yes and is there something called client link we're gonna talk about client link here let me actually go back to a radio that is not an N radio and notice that 802 11 and supported is no and there is no option of client link even there to tick or check select so let's go back and let's take a look at what client link is okay and we actually saw this when we were looking at our access points on Cisco comm and we went to products and services Wireless we went to access points and show products some of these we were able to see there we go weather client link is supported now this is actually client link 2.0 so it's a newer version and we'll talk about the MIMO 4x4 later but and we've already talked a little about clean air we're gonna demonstrate that we can actually see this one doesn't say client link but it does support it the 11:40 supports client link okay so what is client link I actually have a good paper on it here well cisco has a good paper on it here but i've pulled it up and what i want to say also is that i had we've talked about a number of good links to things like whether it be flex connect or understanding h reap i'm actually going to include in this class a number of links and I'll create shortened links you know Google or tiny URL or whatever bit ly so that they're shortened links but these are all cisco.com papers actually one isn't one is just a very very deep level of understanding of radio frequency in general amplitude frequency and phase modulation and all of that sine waves and everything if you care to either a fall asleep to need something to you know read and fall asleep to be are just want to make your head hurt or see actually like me just want to you know really understand absolutely every aspect of something but it's a an University paper but aside from that I'm going to provide a lot of links we took a look at Cisco antennas and specific things to that we're gonna look a little bit more when we come to security at the Cisco compatible extensions program in which CCX or Cisco compatible extensions we need to support certain security aspects because the lab will be testing you on that or not the lab at the exam but we want to talk about client link here real quickly since we've come to it what client link is first of all 802 11 n we have already kind of talked about how it provided remarkable performance improvements and I am yes reading right here in throughput reliability and predictability and the ways that it did this were with things called we talked about how multipath was a bad thing and how 802 11 and turned it on its head to be a good thing okay with M with MIMO with multiple input multiple output and it was able to improve the signal-to-noise ratio by using something called transmit beamforming that was to basically shape the form of that wireless beam in a way that the client with only possibly one antenna could receive that in an optimized fashion now we also talked about if the client had multiple antennas how they could use something called MRC maximal ratio combining so they were either benefiting from having multiple radios and being able to hear let's say we sent three or possibly four antenna signals out of an AP they could hear two or three or four possible signals and they could hear those each individually and then combine them back together that's MRC and the number of antennas - the number of receivers is what we refer to as something by something so let me just draw this real quick I in the 3600 series product page you just saw it you saw four by four okay or sometimes you might see by three you might see three by one you might even see three by two okay this is the transmitted from the radio how many antennas how many radios they have and this is the receiver of the client how many antennas they have to be able to receive so the first number is the AP how many antennas and therefore how many subsequent radios and the second number is the client laptop or PDA smartphone whatever okay that is the number of antennas they have to be able to receive so if I have three most Cisco APs until the thirty-six hundred have three antennas and most clients have one antenna when the Cisco ap has three antennas and there's only two pictured here what this is showing you is that as multipath and reflection off of different devices occurs you can see how they get there but cisco has very specifically in this drawing shown that they get there at slightly different times this has in the past the fact that there was multipath was a problem with 802 11 N and spatially diverse antennas they use that to their advantage with either the client having one antenna and using beamforming so very purposefully shaping the beam shaping the way that this wireless signal is sent out so that they all arrive in a way that complements one another or if the client has multiple receive antennas then with maximal ratio not G not MRG MRC Mash maximal ratio combining okay so looking back at the client only having one antenna let's just say the client only has the Cisco ap has the shows too but let's say the Cisco AP has three antennas and the client has one so we're in a three by one situation okay three by one terrible one in this case with 802 11 n beamforming worked really well that's great we just talked about that what if this is a 802 11 and capable radio but obviously it has the BG capabilities as well so dot 11 B and probably more used as dot 11g these days and let's say this is a dot 11g capable client in other words the the radio the receiver wireless card in here is not incapable so the standard the industry standard of beamforming can't be done why because the client doesn't understand it so there is actually something called client link technology and what this does I'm sorry it's not BG it's AG so that's for the five gigahertz spectrum but what this does is that for AG clients they couldn't do the spatial diversity of beamforming because they didn't have that end standard built in they didn't know you know when the wireless card was built it didn't have any idea of what even beamforming was so that code wasn't built into the silicon so we could and Cisco originally thought about using compatible extensions CCX and we'll talk about more what those are and who participates and which of your laptops you can expect to see it in etc which is almost all of them but not necessarily all but what Cisco did was they realized weak can't necessarily guarantee or quickly quickly enough get out there the ability to have the client really benefit from this beamforming or participate in the beamforming so what they essentially did was they came up with a technology that basically and by the way that beamforming works be in 802 11n because the client is actually responding with information with feedback to the access point so that the access point can maximize or or really create the best possible I should say optimize that algorithm to form the beam in the best way for where that client happens to be located geographically or physically with respect to the surrounding environment the surrounding multipath and with respect to the AP but the 802 11 G is not going to have any feedback so the idea is that cisco created advanced signalling processing and algorithms so that the 802 11 g or possibly a I don't know anyone that's deployed a well at least not since like 2003 without requiring feedback from the client because the client isn't going to be able to do it and therefore it works with all existing AG clients - not quite as perfectly as transmit beamforming works I shouldn't say perfectly because it's not perfect by itself but not quite as good but still make the multi path into something that is beneficial for 802 dot 11g clients and not disruptive so instead of not only being not disruptive but actually improving the the ability for it to work that's what this or the ability to receive this signals for it to be formed properly for that beam to be formed custom that's what client link in essence does without going and reading the whole paper but I do recommend it's a great paper to read I recommend that you go through and look at and read the entire paper it's it's very very informative we will talk about how Cisco compatible extensions interact with this and other features but it's not a bad idea especially if we have 802 at 11 G or possibly a client's to go ahead and enable this client link on 802 11 n radios we can't do this on non 802 11 n radios because the radio has to be able to understand the concept of beamforming before it can help okay but it falls under 802 11 n parameters because it's a product of that of that newer specification and of that newer technology but it client link has nothing to do with n it has to do with a G okay and it's probably I don't know for sure but probably important that you understand it for the exam okay clean air capable we were on our 1262 we also see antenna parameters are we using all three antennas we have an a B and C antenna by the way one of the things that I haven't mentioned yet but is important you may have seen a lot of older ApS that were let's say ABG but not necessarily n and the reason I say that is with n we have more than two antennas possible with a B and G remember we were sending out duplicate copies of the exact same signal over the two antennas and what was the reason for that spatial diversity that way we weren't sending out different copies or different parts of the data as we did with n we're sending up the same copy that way the client could determine which of the two signals was a better quality signal which had a better signal-to-noise ratio when we had those two antennas you might in fact let's just minimize this real quickly you might have seen an AP where those two antennas especially if they were the rubber ducky type the dipole where they came out from the AP and they would go up straight up and if you remember they're they're a plane radiation pattern it was basically something from it for a dipole something like this okay so they were each sending out their radiation patterns you may have seen people that have seen those antennas and thought oh it looks cooler if I do it like this you know so they actually physically tilted those antennas keep in mind what's happening electrically and magnetically they've very drastically changed the pattern of that beam of the the actual wireless signal so instead of being sent out omnidirectional across the room like this they're more you know if this is our horizontal access here they've kind of tilted the signal and it's now going into the floor and up to the ceiling okay not only that but on top of that there is the fact that the wavelength for a 2.4 gigahertz or 5 gigahertz respectively remember when we talked about the fact that frequency was we were able to find 4 wavelength with the math back in I think was module 4 or 5 we talked about RF math and if we know the frequency we can find for wavelength right so if we know that it's 2.4 gigahertz and that's our frequency which we depicted by lambda then we could find for wavelength so wavelength equaled the speed of light divided by frequency or lambda if I'm drawing lambda exactly right we just have to divide this the speed of light by the frequency and we'll find for the wavelength well what you'll find in a 2.4 gigahertz antenna or a 5 gigahertz is that they are inches or centimeters apart depending on how you measure and the way that Cisco is actually positioned these antennas and by the way 2.4 gigahertz and 5 gigahertz right 5 gigahertz is just about not exactly but just about 2 times you know 2 Giga her to point 4 so 2.4 times 2 is really 4.8 so just about thus the same frequency more importantly and much more importantly just about 2 times the wavelength so 2.4 gigahertz frequency I believe is roughly like four point something inches let's just say 4 inches so if I have a 5 gigahertz frequency that's gonna be about 2 inches ok the wavelength decreases as the frequency increases so 4 inches apart from one another and I'm talking about antenna apart from another is really two wavelengths for the 5 gigahertz so there's another reason that these antennas should be upright not only their a plane orientation of radiation but also the wavelength for the given 2.4 megahertz frequency within one second of time that frequency is directly one wavelength apart for the 2.4 gigahertz and it's two wavelengths apart for the 5 gigahertz when you begin turning them like this not only you change the radiation pattern but you skew the amount of wavelengths between each other and they begin to have issues with collisions instead of being working like they should with spatial diversity so it's actually important with dipole antennas to keep them in an upright position so they should be basically pointing towards the sky if you're AP happens to be let's say flat on the table and now I'm looking at the top view then they should be coming straight up if I'm looking at the side view this is the side this is the top if I'm looking at the side view then they should be coming out this direction and then pointing straight up and they should be exactly parallel to one another okay so that antenna positioning is actually not just random okay so anyway now that we're talking about the antennas we're talking about an N capable radio do I have the a B and C antenna is it external in this particular radio that's my only option okay if so what type of antennas do I have connected what's their gain hey do I have a actually that particular the 1260 I have no antenna so I'm just gonna leave that off if I go to my BGN for AP floor one where I can do configure let's enable client link and this says 17 they are most definitely not 17 DVI antennas I actually only have a 6 DB antenna on a and B I don't have one on C okay so 6.5 DB I and it doesn't like 6.5 so let's just give it 6 DB I changing the antenna gain can make the current channel unusable are you sure you want to continue yes to enable client link at least both dual mode antennas a and B should enabled you have one dual-mode antenna okay so actually what I have to do is I have to go back and change my antenna from a and C to a and B so I'll just go ahead and enable those two and during the break I'll make the physical change of that antenna to work with client link okay so not a problem there we can see that the RF channel assignment has been set to 11 but it's done globally okay this is under global configuration that we'll take a look at and it notes that only channels 1 6 and 11 are over are non-overlapping for the US regulatory domain I can click custom and I can override that value if I want but I'm gonna leave it to global if I click custom I can also change the channel width assuming that I actually have well actually I would need to be on an aien radio to change the channel width to 40 megahertz I'm just gonna leave it global for now not sure if that took a not sure if it's just because I didn't have anything to change yep everything's good okay also on this 3500 here's where clean air it's capable and it's disabled by default but I have gone ahead and enabled it and I can also have spectrum expert connected if I had it in se connect mode which I don't and again we'll go over that in the CCNP Wireless site survey class if I go to global configuration I can see that for any given Ethernet interface on any ap I might have ApS that have more than one Ethernet interface and more than one or more than two radio slots is CDP enabled so anything that I do on the radio can be overridden or I can you know basically configure globally so here's my global TCP adjust MSS I would turn that on the pack up primary controller this is in addition this is actually like a fourth option so I had primary secondary tertiary then it goes back up primary and backup secondary again anything that you're confused on or or just want more information on click on help it's not help for this page but I can go to I'm on the wireless tab and then I can look and see I'm under access points and I'm under global configuration and I can see something like let's say high availability it says I can configure primary secondary backup which are if used primary secondary tertiary controllers are not responsive so it goes in this order primary secondary tertiary then primary backup then secondary backup ok so I still want to configure my primary secondary and tertiary on each of my APs you only have to set them up once ok and it gives you all sorts of other information it's really useful the help I can also have login to the individual ApS if I need to do I want to pre download an image do I want to look at ap failover do I want to enable that for global ap failover I'm gonna leave it disabled for right now and what's a heartbeat timer for the AP discovery timer etc ok so we're going to come back and we're gonna take a look at more information this was global configuration to all radios but then there is global configuration to the specific frequencies so this is global configuration that's only ambiguous across 2.4 and 4 gigahertz things like TCP MSS adjust or backup controllers or login credentials or failover but then there are things that are specific to each of the 2.4 this is the 5 gigahertz and the 2.4 gigahertz frequencies and we'll be taking a look at those next [Music]

Channel: Cisco Security

Views: 12,915

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Id: Oxt1tLLtgKA

Length: 59min 42sec (3582 seconds)

Published: Sat Jan 20 2018