BGP Troubleshooting Tips | Border Gateway Protocol

hello everyone how are you hope you all are doing great guys today in this video we are going to troubleshoot BCP Network so here you can see this is my ticket right so ticket is communication not happening between source 30.1.1.1 to destination 10.3.1.1 right so 30.1.1.1 is loopback of router 3 here you can see I am running this IP address okay and destination is look back of router 1 this one is my destination this network okay so first of all let me make you understand this topology as you can see I have three DOTA router one two three on order one I am running bgp 100 on order two I am running bzp 200 and on router 3 I am running bgp 200 that means BCP neighbors ship between daughter 1 and router 2 will be ebgp and BCP neighborship between router 2 and router 3 will be ipzp internal BCP and external BCP okay on all the routers I have created some loopback so as you can see behind router 1 I am running four Network so out of this four Network one network this network [Music] right so router 3 loopback interface of router 3 this one 30.1.1.1 is not able to communicate with 10.3.1.1 okay so I am going to troubleshoot this network that why this user is not able to communicate with this user okay so guys without wasting our time let's begin the configuration I have already configured IP address and BCP protocol on all routers first of all let me show you that so go to router number one and if you will run so IP interface exclude an assigned so you can see over here IP configuration okay after that if you build an so IP protocol so here you can see I am running bzp protocol BCP 100 over here on router one let me show you IP configuration and BCP configuration order router 2. so IP interface brief exclude and assign so you can see these are IP configuration of this router and so IP protocol BCP configuration so see I am running bzp 200 over here let me show you same thing on router 3. so IP interface brief exclude and assign okay so 30.1.1.1 okay so you can see over here this is IP address which is running on loopback one interface right status is up protocol is up but still this interface this user is not able to pin 10.3.1.1 which is running on router 1 interface fine so let me show you bzp protocol so IP protocol so here also you can see I am running bzp 200 so guys to troubleshoot first of all I will check routing table of router 3 right so before that first of all let me verify BCP membership so IP bzp summary so you can see my neighbor is 23.1.1.2 that means on router number two let me show you what IP address I am running here so IP address on this interface is 23.1.1 Dot 2 IP address on this interface is 23.1.1.3 IP address of this interface is 12.1.1.1 and IP address of this interface is 12.1.1.2 so these are IP configuration okay so here on dotted three you can see my neighbor is 23.1.1.1 1.2 which type of neighbor it is it is ibgp neighbor because as number is 200 here also okay on both router Router 2 and router 3 I am running same as number so this is ibgp neighbor now I am going to check routing table of this router so IP root BCP okay so guys in the routing table of this router you can see there are all 20s Network there are tens network 10.1.1.0 network via 23.2 means via router 2 that means I am getting Roots via router number two so I am getting this root as well I am getting root for this network as well but here you can see I am not receiving a root for 10.3.1.0 Network right 10.1.3.0 network is missing from here so what next thing I will check I will check BCP table so IP bzp so here also you can see 10.4.1.010 Dot one dot two dot okay so all are available except 10.3.0 so in BCP table also you can see 10.3.1.0 network is not available so what I am going to check here first of all this prefix this router is getting these prefix from router 2. so I am going to check that how many prefix this router learn from router 2 I am going to check that that how many roots router 2 advertise to router 3 for that so IP bzp neighbor neighbor is 23.1.1.2 and received root receive routes okay so it's saying inbound soft reconfiguration is not enabled so first of all we need to enable inbound soft reconfiguration so go to router BCP 200 and after that you will run command neighbor [Music] 23.1.1.2 and soft reconfiguration okay inbound let me hit enter and now let me run this command that how many so see these are all prefix which router 3 learned from router 2 which routed two advertise to router three so here also you can see router 2 is not advertising 10 Dot 3.1.0 Network right apart from that Network all networks are here all networks router 2 is advertising to router 3. so problem is router 2 is not advertising 10.3.1.0 Network 2. router 2 is not advertising two router three so now I am going to check configuration on router number two that y rotor 2 is not advertising 10.1.3.0 Network so first of all let me check so IP root bgp yeah that this router is receiving 10.3.1.0 Network or not so yes this router have this network you can see in the routing table of this router 10.3.1.0 fine via router number one who is advertising 12.1 router number one is advertising so first of all let me check something on router number one so IP pgp neighbor 12.1.1.2 and I am going to check that which network how many networks this router is advertising to router number two so I am asking to this router that tell me the advertised route advertised route to router number two so it's saying that it is advertising these prefix right 10.1.1.0 10.2.1.010.3.1.0 10.4.1.0 okay so everything is fine here right for all next stop is zero that means this order is advertising this network this these all networks exist on their self right on daughter one so for self Edward taste prefix next hub will be 0.0.0 okay now what we need to check now you can check running configuration BCP configuration over here so so run and pipe section bgp let me check how many command Engineers have run here so let me maximize it okay Network this one this one is fine this one is also fine this one is also fine and neighbor 12.1.1 Dot two remote s is 200 never 12.1.1.2 root map received in so there are some root map as well okay so as you can see root map received and root map advertise let me check root map so root map received ok so here you can see access list 10 is 20 is configured and here I need to check advertised so access list 10 let me check access list 10 as well so IP access list 10. so here all networks are permitted right to advertise okay so this one is all a configuration on router 1 is fine right there is no any problem so these root router can learn and this root rotor can advertise in bgp fine okay let me check configuration of router 2 now okay so here only we need to troubleshoot on router number two problem is definitely on router 2 because router 2 is also receiving 10.3.1.0 network but this router is not advertising to their neighbor for that what we need to do we need to troubleshoot here so from here I am going to check that how many Network this router is advertising to router 3 so so IP bzp neighbor 23.1.1.3 and advertised route so this router is advertising 10.2.1.010.4.1.0 okay and 10.1.1.020 okay so accept 10.3.1.0 this order is advertising all prefixes so why the software is not advertising 10.3.1.0 let me check received root here from router 1. neighbor 12.1.1.1 and received route so here also you can see we need to enable soft reconfiguration so router bzp 200 and say neighbor is 12.1.1.1 soft reconfiguration in bond okay now you can see this router is receiving these prefix from their ebgp neighbor from router number one now guys I need to check running configuration because everything is fine till now now I am going to check so run a section BCP so here let me maximize it and let me check how many command Engineers have configured here so Network 20 2020 Network 30 okay so on this router I have run this command as well so I don't think that we need this command here I don't need to run this command because this network command we need to run on router number three okay but no problem we can remove it but here my problem is because of maybe this root map here you can see with never 20.1.1.3 there is one root map right with never 20.1.1.3 next hop self command is already running so that's why a router from router 3 look back of router 1 is reachable okay so this command is already running here and neighbor this one okay so I need to check this root map right I think problem is here 100 problem is here so root map and received so here you can see I have configured access list 50 so let me check access list 50 so access list 50. and here you can see 10 permit 10.1 Dot 1.0 20 permit 10.2.1.0 okay so here you can see 10.3.1.0 command is missing right so in Access list 50 we need to permit 10.1.10.3.1.0 Network as well because this one is received root tab so this router is not going to advertise 10.1.3 10.3.1.0 to router number three because here I have configured root map so what we need to do go to access list 50 access list 50 and here we need to access list 50 permit and say 10.3 Dot 1.0 wildcard mask is 0.0.255 after running this command let me check routing table of router 3 now so IP root BCP so steal this router does not have Roots 410.3.1.0 Network okay so what we need to do just let me clear BCP clear IP bgp star soft in let me run this command here and now I am going to check so IP root BCP again so now you can see here 10.3.1.0 network is available in the routing table of router 3. can I ping now ping 10.1 dot sorry 10 Dot 3.1.1 and source is source is 30.1.1.1 let me check and yes now I am able to ping you can see right so this is how you can triple shoot right in next video we will discuss something else this is uh the reason why this loopback interface was not able to Ping 10.3.1.1 is root map configured on router 2 because of root map configuration on router 2. so these are the step you will follow while troubleshooting the network so suppose from router 3 if a network is if a user or if a network is not able to Ping so what we need to do first of all we need to check routing table of this router bzp table BCP Network table right root map access list these things BCP configuration if everything is fine over here then we will check on daughter one that router 1 is advertising everything or not router 3 is advertising this prefix or not is there any root map for advertised prefix or is there any misconfiguration of BCP after that we will check routing table of router 2 that in the routing table of router 2 is this network available if this network is available in the routing table of router 2 but router 2 is not advertising to router 3 that means maybe that there is access this Con access list is configured a root map is configured so we need to check those things then definitely you will get some you will get problem right what is the issue that why machines are not able to communicate with each other okay guys so that's all for today we will meet soon in next video till then stay safe if you learn something from this video please don't forget to hit on like button and if you haven't subscribed my Channel Please Subscribe this channel bye bye

Channel: PM Networking

Views: 9,651

Keywords: computer networks, dns, cyber security course, ccna, computer network, ccna 200-301 full course, computer networking, comptia network+, comptia network+ full course, network security, security+, vlan, router configuration step by step, ccna course, palo alto firewall, troubleshooting network problem, bgp protocol, network engineer course, ccna 200-301, network engineer life, technical course for network engineer, ccnp, ccnp full course

Id: Y1u2uEQWXn8

Length: 18min 9sec (1089 seconds)

Published: Sun Feb 05 2023