As we all know, configuring the BGP neighbor isn’t too troublesome, however when we’re going to configure 100 or extra Variety of neighbors, then it turns into fairly tedious exercise.
BGP Peering
To reduce this configuration overhead, we use the idea of BGP peer Group, the place we will group the BGP Neighbors who’re sharing the identical outbound insurance policies. However first, we have to manually configure 100 Friends after which add to the peer group. Therefore the issue remains to be not resolved.
Associated – BGP Neighbor States
Let’s confirm BGP peer Group configuration
1 Instance: Configuration step of iBGP Peer Group.
2 Instance: Configuration step of eBGP peer Group.
Associated – iBGP vs eBGP
With the Dynamic BGP peering function, BGP router dynamically establishes peering with a bunch of distant neighbors which can be configured utilizing a variety of IP addresses and BGP peer group. After a subnet vary is configured for a BGP peer group and a TCP session is initiated by one other router for an IP deal with within the subnet vary, a brand new BGP neighbor is dynamically created as a member of that group.
So on this state of affairs, we are going to talk about find out how to configure Dynamic BGP peer.
(Diagram- BGP Peering)
As per diagram R1 needs dynamic peering with R2 and R3, so let’s confirm the configuration steps;
Step 1. Outline BGP peer group identify
R1(config-router)# neighbor Dynamic-peer peer-group
Step 2. Create a world restrict of BGP dynamic subnet vary neighbors. The worth ranges from 1 to 5000.
R1(config-router)# bgp hear restrict 100
Step 3. Outline the IP Subnet Vary and affiliate it with a peer group. A number of subnets might be added to the identical peer group.
R1(config-router)# bgp hear vary 172.16.0.0/16 peer-group Dynamic-peer
Step 4. Outline the remote-as for the peer group. Optionally, outline the listing of AS numbers that may be accepted to type neighborship with. The max restrict of alternate-as numbers is 5.
R1(config-router)# neighbor Dynamic-peer remote-as 65002 alternate-as 65003 65004
Step 5. Activate the peer group underneath ipv4 address-family
R1(config-router-af)# neighbor Dynamic-peer activate.
Router1#present run | part router bgp
bgp log-neighbor-changes
bgp hear vary 172.16.0.0/16 peer-group Dynamic-peer
neighbor Dynamic-peer peer-group
neighbor Dynamic-peer remote-as 65002 alternate-as 65003 65004
!
address-family ipv4
neighbor Dynamic-peer activate
exit-address-family
Router2#present run | part bgp
bgp log-neighbor-changes
neighbor 172.16.1.1 remote-as 65001
Router3#present run | part router bgp
bgp log-neighbor-changes
neighbor 172.16.2.1 remote-as 65001
Router1#present ip bgp abstract
BGP desk model is 1, major routing desk model 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
*172.16.1.2 4 65002 4 4 1 0 0 00:00:38 0
*172.16.2.2 4 65003 4 2 1 0 0 00:00:29 0
* Dynamically created based mostly on a hear vary command
Dynamically created neighbors: 2, Subnet ranges: 1
BGP peer group Dynamic-peer hear vary group members:
172.16.0.0/16
Whole dynamically created neighbors: 2/(100 max), Subnet ranges: 1
Router1#present tcp transient all
A2B61B90 172.16.1.1.179 172.16.1.2.64321 ESTAB
A2B62F48 172.16.2.1.179 172.16.2.2.17764 ESTAB
A2B19B20 0.0.0.0.179 *.* LISTEN
The output illustrates that the router is listening on port 179 however with international deal with of *.*
Associated- BGP Interview Questions
