04-06-2020 07:54 AM - last edited on 01-27-2022 11:07 AM by Translator
Hello team:
I have the following output in my Cisco router to the "show ip bgp 172.25.159.140 255.255.255.252" command:
LASBRUOL1001-1#show ip bgp 172.25.159.140 255.255.255.252
BGP routing table entry for 172.25.159.140/30, version 1073122
Paths: (2 available, best #2, table default)
Advertised to update-groups:
142
Refresh Epoch 1
65631, (received-only)
172.25.159.99 from 172.25.159.99 (172.25.159.81)
Origin IGP, localpref 100, valid, external
rx pathid: 0, tx pathid: 0
Refresh Epoch 1
3549 65134 65318, (received & used)
172.31.2.17 from 172.31.2.17 (172.31.2.17)
Origin incomplete, localpref 100, valid, external, best
Extended Community: RT:13835:1100035
rx pathid: 0, tx pathid: 0x0
I am interested in the "bold section", and specifically in the "red" IP address between parenthesis. It says the prefix is being learnt from AS 65631 and neighbor 172.25.159.99. ¿ Can you please explain what attribute does the IP address 172.25.159.81 between parenthesis represent? It can not be the NEXT-HOP attribute, since it is my understanding that the NEXT-HOP attribute of announcements from an external neighbor should/must be the IP address of the external neighbor..
Any hints will be greatly appreciated.
Best regards, Rogelio
Solved! Go to Solution.
04-06-2020 08:48 AM
Hi,
For all BGP prefixes, you're gonna see these 3 values, which depending on the BGP design, can have the same or different values:
A.A.A.A from B.B.B.B (C.C.C.C)
A.A.A.A is the next-hop value of the prefix
B.B.B.B is the IP address of the BGP peer over which the BGP TCP session is formed
C.C.C.C is the BGP router-ID of the BGP peer you got this route from
So that value is the BGP router-ID of your BGP peer.
Regards,
Cristian Matei.
04-06-2020 08:48 AM
Hi,
For all BGP prefixes, you're gonna see these 3 values, which depending on the BGP design, can have the same or different values:
A.A.A.A from B.B.B.B (C.C.C.C)
A.A.A.A is the next-hop value of the prefix
B.B.B.B is the IP address of the BGP peer over which the BGP TCP session is formed
C.C.C.C is the BGP router-ID of the BGP peer you got this route from
So that value is the BGP router-ID of your BGP peer.
Regards,
Cristian Matei.
04-06-2020 08:52 AM
Thanks for clearing this up! Best regards, Rogelio
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