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BGP Dynamic Peering

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  As we know, configuring the BGP neighbor is not too difficult, but when we are going to configure 100 Number of neighbors, then it cloud be tedious. So to minimize this configuration we have BGP peer Group, in which we can group the BGP Neighbors who are sharing the same outbound polices, either the BGP Neighborship is  iBGP  or  eBGP . But the first we need to manually configure 100 Peer and then add to the peer group. So the problem is still not resolved. Let’s verify BGP peer Group configuration 1 Example : Configuration step of  iBGP  Peer Group. 2 Example:  Configuration step of  eBGP  peer Group. With the Dynamic BGP peering feature, BGP router dynamically establish peering with group of remote neighbor that are configured using a range of IP addresses and BGP peer group. In the Dynamic BGP peering, BGP peer tries to establish a BGP neighborship, if the neighbor router initiate TCP session because Dynamic BGP peer configuration router...
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BGP Neighbor States

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  BGP is designed for handle large amount of routing information and Complex Networks, BGP enable routers create TCP connection with neighbor that is called BGP Peers. BGP neighbors are manually configured, when we configure BGP neighbor, it goes through different stages before it reaches the desired state (Established State).   BGP Session goes through following stages: 1)      Idle state : In this state, BGP enable router detects start event (start event occur when we configure new neighbor or reset already established neighbor peering), and tries to initiates a TCP connection to the BGP peer, and also listening new BGP peer router, who tries to establish new connection. If successful, BGP state changes to connect state, if any error cause in this state, BGP router again back to the idle state, the ConnectRetryTime is set to 60 secs, and re-initiate connection when decrement to zero. Further failure results doubling ConnectRetryTime in the length from previous...
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MBGP vs BGP

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  MBGP vs BGP Currently BGP is running in version 4, which has been published in 2006 (RFC 4271). By default, BGPv4 only supports IPv4 unicast prefixes, But BGP can do much more than carrying IPv4 prefixes only. RFC 4760 Multiprotocol extensions for BGPv4 was written in order to enhance the capacity of carrying routing related information other than carrying ipv4 only.     Multiprotocol Extensions for BGPv4 added some new attributes. ·          Multiprotocol Reachable NLRI (MP_REACH_NLRI): It carry set of reachable destination with next-hop information. ·          Multiprotocol Unreachable NLRI (MP_UNREACH_NLRI): It carry set of unreachable destinations.   Note: - “MP_REACH_NLRI” and “MP_UNREACH_NLRI” are optional and Non-transitive attribute, because of this if neighbor doesn’t support the multiprotocol capabilities, it will just ignore information carried in these attributes and will...
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Troubleshooting BGP Neighbor States

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Troubleshooting BGP Neighbor Relationships 1 Example: - Troubleshoot Directly connected EBGP neighbors In this scenario two routers are creating EBGP session with directly connected Interface IP. Let verify configuration; R1 Router1#show run | section router bgp router bgp 65001 bgp log-neighbor-changes neighbor 192.168.10.2 remote-as 65002   R2 Router2#show  run | section router bgp router bgp 65002 bgp log-neighbor-changes neighbor 192.168.10.1 remote-as 65001 Now run “ show ip bgp summary ” to check BGP memory use, and displays BGP neighbors and the state of communication. Router1#show ip bgp summary BGP router identifier 10.10.10.1, local AS number 65001 BGP table version is 1, main routing table version 1   Neighbor        V       AS       MsgRcvd   MsgSent   TblVer   InQ   OutQ Up/Down   State...
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