No Prefix recieved in eBGP

[MSJ1]

Hi,

I had one ebgp running. All on a sudden I see no prefix received. But opposite side of bgp is receiving routes. 

I control the received routes using a simple prefix list. Prefix name was changed and apparently after that seeing no bgp prefix received.

tried to reset the tunnel ( shutdown and unshut bgp neibgr ) but did not help.

I see in the received route command it shows remote subnet but received prefix is zero.

What could be the issue  ?

What debug command I should run  ?

==========================================

router bgp 64512
bgp log-neighbor-changes
neighbor 172.25.25.25 remote-as 12076
neighbor 172.25.25.25 password CCCCCCCCCCCCCCC
neighbor 172.25.25.25 update-source Vlan101
!
address-family ipv4
redistribute ospf 100 match internal external 1 external 2
neighbor 172.25.25.25 activate
neighbor 172.25.25.25 soft-reconfiguration inbound
neighbor 172.25.25.25 route-map Remote_Prefixes_Inbound in
exit-address-family

route-map Remote_Prefixes_Inbound permit 10
match ip address prefix-list Remote_Prefixes_Inbound

ip prefix-list Remote_Prefixes_Inbound seq 10 permit 172.27.16.0/21

======================================================================================
sh ip bgp neighbors 172.25.25.25 received-routes
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
* 172.27.16.0/23 172.25.25.25 0 12076 i
* 172.27.18.0/23 172.25.25.25 0 12076 i
* 172.27.20.0/23 172.25.25.25 0 12076 i

======================================================================================

show ip bgp summary

BGP router identifier 172.23.1.1, local AS number 64512
BGP table version is 1012, main routing table version 1012
422 network entries using 60768 bytes of memory
425 path entries using 34000 bytes of memory
14/13 BGP path/bestpath attribute entries using 2240 bytes of memory
2 BGP AS-PATH entries using 48 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 97056 total bytes of memory
3 received paths for inbound soft reconfiguration
BGP activity 427/5 prefixes, 446/21 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
172.25.25.25 4 12076 1705 1729 1012 0 0 1d01h 0

[MHM Cisco World · Accepted solution]

neighbor 172.25.25.25 route-map Remote_Prefixes_Inbound in <<- inbound 
exit-address-family

route-map Remote_Prefixes_Inbound permit 10
match ip address prefix-list Remote_Prefixes_Inbound

ip prefix-list Remote_Prefixes_Inbound seq 10 permit 172.27.16.0/21

======================================================================================
sh ip bgp neighbors 172.25.25.25 received-routes
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
* 172.27.16.0/23 172.25.25.25 0 12076 i <<- non is permit by prefix-list 
* 172.27.18.0/23 172.25.25.25 0 12076 i <<- non is permit by prefix-list 
* 172.27.20.0/23 172.25.25.25 0 12076 i <<- non is permit by prefix-list 

as @Harold Ritter  mention you can use /21 le 23

[balaji.bandi]

I control the received routes using a simple prefix list. Prefix name was changed and apparently after that seeing no bgp prefix received.

You mean after adding in

prefix list

its not working, what is the outcome, if you remove 

neighbor 172.25.25.25 route-map Remote_Prefixes_Inbound

in  ( and do soft reset ) is that works ?

i would like to test simple here prefix names, all looks same.

can you differentiate them rather all in one name.

route-map Remote_Prefixes_Inbound permit 10
match ip address prefix-list Remote_Prefixes_Allow

ip prefix-list Remote_Prefixes_Allow seq 10 permit 172.27.16.0/21

[Harold Ritter · Accepted solution]

Hi @MSJ1 ,

The current

prefix-list

will not accept the /23 prefixes. You need to change it as follow:

ip prefix-list Remote_Prefixes_Inbound seq 10 permit 172.27.16.0/21 le 23

Regards,