BGP Synchronization Rule - Video By Sikandar Shaik || Dual CCIE (RS/SP) # 35012

[Music] in this video we are going to learn about a synchronization rule if you remember in all overlaps mostly on all our basic labs everywhere we are use a command called no synchronization no and while we are using that command why we need to disable that command if I don't do that what exactly happens let's try to understand what is singing as a control so synchronization rule says that it's a default rule which is enabling your BGP in the older version of the BGP now what if this synchronization rule is enabled it's going to say that do not use or advise any route to an external bgp neighbor which is learn from your ibgp until unless and until you have at the same matching route learn from your ICP protocol let me explain this scenario here take an example you are having ones out let's say I'm going to have 10 dot Network on my router C and this standard network is getting advertised to router a through bgp so i'm going to realize this network through bgp in the bgp network command now allowed us a is not going to advertise this route to any of the external bgp neighbors so it's not going to advise so why it is not going to all - because the synchronization rule says that do not or dyes are out if the same network if this let work if it is not learn from your IGP so which means whatever the network you are using that network it should be allowed as in bgp at the same time it should also be added as in your IGP so every route will be able - only if it is added as in your BGP and also it should be read as new IDP ICP means you any of the OSPF EIGRP or our IP protocols which means every Network which you are dancing to analyzing in BGP must also be authorized in your ICP also then only this border router way it will not use it it says it's not going to use at the same time it's not going to advertise to any route unless and until the same matching route is also learn why are I GP so that is what this synchronization rule says in the recent iOS this pre synchronization rule is by default disabled with a command with called no synchronization now if you want you can even enable with synchronization if you enable synchronization it becomes mandatory for you to otherwise each and every is out inside your ITP in both your IDP protocol and also in your PCB protocol so that is the thing we need to come to so this is what synchronization rule so I just to ensure consistency this rule was there so it is always safe to have it off only if all the routers in the transit path is running just a full measure of ibgp and we can disable with a command called no synchronization and from I was told to release probably most of the I ways will have default no synchronization disabled if you want to enable it back we can use a command called synchronization again so when you say synchronization which means that particulars out whatever the dead not Network it has to be an adult in your BGP and also it has to be read as in ICP in order to ensure that this route should be authorized to any of the ebgp neighbor so that is there is a mandatory rule since five to remonstrate verify the same synchronization with a basic simple lab so I got my topology here you can see the same default topology I'm using now here I got three routers router one is going to be it with raptor two and then the after three now what I am going to do is I'm going to use this network so first will enable no synchronization in all the routers will disable it and will configure some basic ibgp and ebgp configurations let's try to do that so that is very simple we already did these things in our previous laps if you remember so I'm going to mine out of one and if I see YP b GP I don't have BGP running and if I give show IP protocols I don't have any of the routing protocol running here so just a blank IP addressing so I'm going to bgp router bgp 500 i will configure router 2 by using my directly tonight interface remote a is is 600 it's an e BGP neighbor and then no auto summary no synchronization so I'm just going with a simple basic configuration by disabling the no synchronization network 10 dot network and one interface one network for the same thing I'll go to my after two I will configure the basic bgp router bgp 600 notice summary no synchronization neighbor one now 1.1.1 which is my route of one remote ase is 500 and the neighbor 2.2 dot 2.2 which is my router 3 600 and then network I'm going to advertise my credit or network to door network and one dot network which are my van interface now let me quickly configure router 3 ourselves outer bgp 600 no auto summary no synchronization network readout network our LAN interface and then advertising my van interface and neighbor command I am missing go door-to-door float one remote se6 circuit so it's my internal v-chip enable now verification wise if I go to router to I should see two neighbors one neighbor is my internal neighbors internal neighbor is too low - OH - OH - it should come up okay so let me check the corner you can see the neighbor ship is up if I go show IP BGP summary and from each Lebanon I'm learning to do rocks and if I verify show IP BGP I can see these routes in my BGP table and also if I verify show IP route I can I can also see that those troughs coming into my routing table as well now what I'm going to do is I'm going to vary from the router one also now you can see the door network is coming and if I give shy PSLV GP that any road network is also coming on dr one so here I am not running any ICP protocol I'm simply running a normal PCP okay with a basic IP c pn e bgp configuration so now router 3 is going to advertise this route to the router to router 2 is going to add a shorter one and now 2 is going to advance it out to 1 because we have enabled no synchronization so when you say no synchronization it ensures that even though this route so it is not advertised in IGP it is it is no it is still going to advertise that's what we are going to disable the synchronization know what I'll do is I will go to router 2 and I will simply say no synchronization I will rename canonization on the router that's what I am going to do now so once I do that let us see what happens so I'll go to router 2 or we can just go to every router and you can do that I will simply enable the synchronization and then I will verify show IP BGP you can see the route is coming into my BGP routing table if I check my routing table so I'll try to create the BGP things how clear the BGP peering clear IP BGP so just to ensure that if you try to see here if I give show IP route show IP BGP I can see the route is learn in the BGP table but you'll see only star star the present is just a valid route but it's not getting installed into my routing table now if you see here this study door network is not getting installed the routing table and the reason is as per our synchronization rule now I enable synchronization this route when any doubt is advertised by internal labor now router 2 should not use and also it should not advertise which means router 2 is not going to install that doubt in the routing table at the same time it is also not going to advertise to any of the external bgp neighbor so that's what we'll see here as well you can see what is our network is not at all in my BGP table so if it is not in the BGP table definitely you don't see that route in your routing table also so now there are two possible solutions either you disable the synchronization rule that's what we can that's what's recommended anyway but this is just a lab a small lab for demonstrating how the synchronization rule works so we can simply say no synchronization or just go and configure IGP and advertise your IGP so you can just follow anyone of this solution so anyway I am going to disable that synchronization on the router - once again I will simply say no synchronization and now clear the BGP process so they said your neighbor ship once again and if I verify the neighbor ship the neighbors ship let us come up and if I verify show IP BGP you can see $30 out comes into my B P routing table as the last into my routing table here so BGP table I can see it and also it is in the routing table now router 2 is going to use that route and also it is going to advertise to its external bgp neighbor so this is one small lap which is going to demonstrate how the synchronization rule works [Music]

Channel: Sikandar Shaik

Views: 54,093

Keywords: border gateway protocol (bgp), border gateway protocol explained, border gateway protocol in computer networks, border gateway protocol configuration, border gateway protocol definition, what is border gateway protocol, how border gateway protocol works, what is border gateway protocol in networking, MicroNugget, cbt nuggets, computer based training, cbt, BGP, Border Gateway Protocol, routing protocols, bgp training, What is BGP?, bgp

Id: 5i8IJCIj7ZM

Length: 11min 35sec (695 seconds)

Published: Mon Mar 06 2017