Solved: Why is my router not receiving prefixes?

hfakoor222 · ‎06-04-2022

B3 not receiving BGP prefixes from C3

Prefixes advertised via core C3 router

B3   Router

 Invalid input detected at '^' marker.




B3#sh ip bgp




B3#

B3#

B3#sh run

Building configuration...




Current configuration : 4003 bytes

!

upgrade fpd auto

version 12.4

service timestamps debug datetime msec localtime show-timezone year

service timestamps log datetime msec localtime show-timezone year

service password-encryption

!

hostname B3

!

boot-start-marker

boot-end-marker

!

logging message-counter syslog

!

aaa new-model

!

!

!

!

aaa session-id common

no ip source-route

no ip icmp rate-limit unreachable

ip cef

!

!

!

!

no ip domain lookup

ip domain name ws.nsrc.org

ipv6 unicast-routing

no ipv6 source-route

ipv6 cef

!

multilink bundle-name authenticated

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

archive

 log config

  hidekeys

!

!

!

!

!

ip tcp synwait-time 5

ip tcp path-mtu-discovery

!

!

!

!

interface Loopback0

 description Loopback on Core

 ip address 100.68.3.1 255.255.255.255

 ipv6 address 2001:DB8:3::1/128

!

interface Null0

 no ip unreachables

 no ipv6 unreachables

!

interface FastEthernet0/0

 description Link to Central

 ip address 100.122.1.1 255.255.255.254

 duplex half

 ipv6 address 2001:18:0:12::1/127

!

interface FastEthernet1/0

 no ip address

 shutdown

 duplex auto

 speed auto

 isis network point-to-point

 isis metric 2

!

interface FastEthernet1/1

 description Link to Central Router

 ip address 100.68.3.17 255.255.255.254

 no ip redirects

 no ip proxy-arp

 ip router isis as30

 duplex auto

 speed auto

 ipv6 address 2001:DB8:3:10::1/127

 ipv6 nd prefix default no-advertise

 ipv6 nd ra suppress

 ipv6 router isis as30

 isis network point-to-point

 isis metric 2

 isis csnp-interval 10

 isis ipv6 metric 2

!

router isis as30

 net 49.0001.0003.0001.00

 is-type level-2-only

 metric-style wide

 set-overload-bit on-startup wait-for-bgp

 log-adjacency-changes all

 metric 100000

 default-information originate route-map DEFAULT-ORIG

 !

 address-family ipv6

  multi-topology

  set-overload-bit on-startup wait-for-bgp

  metric 100000

  default-information originate route-map DEFAULT-ORIGv6

 exit-address-family

!

router bgp 30

 no bgp default ipv4-unicast

 bgp log-neighbor-changes

 bgp deterministic-med

 neighbor ibgp-rr peer-group

 neighbor ibgp-rr remote-as 30

 neighbor ibgp-rr description iBGP with RReflector Core

 neighbor ibgp-rr update-source Loopback0

 neighbor ibgpv6-rr peer-group

 neighbor ibgpv6-rr remote-as 30

 neighbor ibgpv6-rr description iBGP with RR

 neighbor ibgpv6-rr update-source Loopback0

 neighbor 2001:18:0:12:: remote-as 121

 neighbor 2001:18:0:12:: description eBGP with TRANSIT N

 neighbor 2001:DB8:3::2 peer-group ibgpv6-rr

 neighbor 2001:DB8:3::2 description iBGP with Core

 neighbor 100.68.3.2 remote-as 30

 neighbor 100.68.3.2 peer-group ibgp-rr

 neighbor 100.68.3.2 description iBGP with Core

 neighbor 100.122.1.0 remote-as 121

 neighbor 100.122.1.0 description The Link To The TRANSIT Net

 neighbor 100.122.1.4 remote-as 121

 !

 address-family ipv4

  neighbor ibgp-rr send-community

  neighbor ibgp-rr next-hop-self

  neighbor 100.68.3.2 activate

  neighbor 100.122.1.0 activate

  distance bgp 200 200 200

  no auto-summary

  no synchronization

 exit-address-family

 !

 address-family ipv6

  neighbor ibgpv6-rr send-community

  neighbor ibgpv6-rr next-hop-self

  neighbor 2001:18:0:12:: activate

  neighbor 2001:18:0:12:: prefix-list FULL-v6ROUTES in

  neighbor 2001:DB8:3::2 activate

  distance bgp 200 200 200

 exit-address-family

!

ip forward-protocol nd

ip route 100.68.1.5 255.255.255.255 100.122.1.0

ip route 100.122.1.5 255.255.255.255 100.68.1.5

no ip http server

no ip http secure-server

!

!

!

!

ip prefix-list DEFAULT-ROUTE seq 5 permit 0.0.0.0/0

!

ip prefix-list FULL-ROUTES seq 5 permit 0.0.0.0/0 le 32

no cdp log mismatch duplex

!

!

ipv6 prefix-list DEFAULT-v6ROUTE seq 5 permit ::/0

!

ipv6 prefix-list FULL-v6ROUTES seq 5 permit ::/0 le 128

!

!

!

!

!

control-plane

!

!

!

!

!

!

!

gatekeeper

 shutdown

!

!

line con 0

 exec-timeout 0 0

 privilege level 15

 logging synchronous

 transport preferred none

 stopbits 1

line aux 0

 exec-timeout 0 0

 privilege level 15

 logging synchronous

 transport preferred none

 stopbits 1

line vty 0 4

 transport preferred none

!

end



















C3  Router 




> 100.68.3.0/24 0.0.0.0 0 32768 i
*>i100.68.3.64/26 100.68.3.4 0 100 0 i
C3#sh ruin
^
% Invalid input detected at '^' marker.

C3#sh run
Building configuration...

Current configuration : 5050 bytes
!
upgrade fpd auto
version 12.4
service timestamps debug datetime msec localtime show-timezone year
service timestamps log datetime msec localtime show-timezone year
service password-encryption
!
hostname C3
!
boot-start-marker
boot-end-marker
!
logging message-counter syslog
!
aaa new-model
!
!
!
!
aaa session-id common
no ip source-route
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
ip domain name ws.nsrc.org
ipv6 unicast-routing
no ipv6 source-route
ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
log config
hidekeys
!
!
!
!
!
ip tcp synwait-time 5
ip tcp path-mtu-discovery
!
!
!
!
interface Loopback0
description Loopback on Core
ip address 100.68.3.2 255.255.255.255
ipv6 address 2001:DB8:3::2/128
!
interface Null0
no ip unreachables
no ipv6 unreachables
!
interface FastEthernet0/0
description Link to Peering
ip address 100.68.3.18 255.255.255.254
no ip redirects
no ip proxy-arp
ip router isis as30
duplex half
ipv6 address 2001:DB8:3:11::/127
ipv6 nd prefix default no-advertise
ipv6 nd ra suppress
ipv6 router isis as30
isis network point-to-point
isis metric 2
isis ipv6 metric 2
!
interface FastEthernet1/0
description Link to Border Router
ip address 100.68.3.16 255.255.255.254
no ip redirects
no ip proxy-arp
ip router isis as30
duplex auto
speed auto
ipv6 address 2001:DB8:3:12::/127
ipv6 nd ra suppress
ipv6 router isis as30
isis network point-to-point
isis metric 2
isis ipv6 metric 2
!
interface FastEthernet1/1
description Link to A3 Access
ip address 100.68.3.20 255.255.255.254
no ip redirects
no ip proxy-arp
ip router isis as30
duplex auto
speed auto
ipv6 address 2001:DB8:3:10::/127
ipv6 nd ra suppress
ipv6 router isis as30
isis network point-to-point
isis metric 2
isis ipv6 metric 2
!
router isis as30
net 49.0001.0003.0002.00
is-type level-2-only
metric-style wide
log-adjacency-changes all
metric 100000
passive-interface Loopback0
!
address-family ipv6
multi-topology
metric 100000
exit-address-family
!
router isis as40
is-type level-1
set-overload-bit on-startup wait-for-bgp
log-adjacency-changes all
!
router bgp 30
bgp log-neighbor-changes
neighbor ibgp-full peer-group
neighbor ibgp-full remote-as 30
neighbor ibgp-full description Full Routes
neighbor ibgp-full update-source Loopback0
neighbor ibgpv6-full peer-group
neighbor ibgpv6-full remote-as 30
neighbor ibgpv6-full description Full Routes
neighbor ibgpv6-full update-source Loopback0
neighbor ibgp-partial peer-group
neighbor ibgp-partial remote-as 30
neighbor ibgp-partial description Local Routes only
neighbor ibgp-partial update-source Loopback0
neighbor ibgpv6-partial peer-group
neighbor ibgpv6-partial remote-as 30
neighbor ibgpv6-partial description Local Routes only
neighbor ibgpv6-partial update-source Loopback0
neighbor 2001:DB8:3::1 peer-group ibgpv6-full
neighbor 2001:DB8:3::1 description iBGP with Bord
neighbor 2001:DB8:3::3 remote-as 30
neighbor 2001:DB8:3::4 remote-as 30
neighbor 100.68.3.1 remote-as 30
neighbor 100.68.3.1 peer-group ibgp-full
neighbor 100.68.3.1 description iBGP with Border
neighbor 100.68.3.3 peer-group ibgp-partial
neighbor 100.68.3.3 description iBGP with Peering
neighbor 100.68.3.4 peer-group ibgp-partial
neighbor 100.68.3.4 description iBGP with Access
!
address-family ipv4
neighbor ibgp-full send-community
neighbor ibgp-full route-reflector-client
neighbor ibgp-full next-hop-self
neighbor ibgp-partial send-community
neighbor ibgp-partial route-reflector-client
neighbor ibgp-partial next-hop-self
neighbor ibgp-partial filter-list 10 out
no neighbor 2001:DB8:3::1 activate
no neighbor 2001:DB8:3::3 activate
no neighbor 2001:DB8:3::4 activate
neighbor 100.68.3.1 activate
neighbor 100.68.3.3 activate
neighbor 100.68.3.4 activate
no auto-summary
no synchronization
network 100.68.3.0 mask 255.255.255.0
network 100.68.3.28 mask 255.255.255.252
exit-address-family
!
address-family ipv6
neighbor ibgpv6-full send-community
neighbor ibgpv6-full route-reflector-client
neighbor ibgpv6-full next-hop-self
neighbor ibgpv6-partial send-community
neighbor ibgpv6-partial route-reflector-client
neighbor ibgpv6-partial next-hop-self
neighbor ibgpv6-partial filter-list 10 out
neighbor 2001:DB8:3::1 activate
neighbor 2001:DB8:3::3 activate
neighbor 2001:DB8:3::4 activate
network 2001:DB8:3::/48
network 2001:DB8:3:21::/64
exit-address-family
!
ip forward-protocol nd
ip route 100.68.3.0 255.255.255.0 Null0
no ip http server
no ip http secure-server
!
ip as-path access-list 10 permit ^$
!
!
no cdp log mismatch duplex
ipv6 route 2001:DB8:3::/48 Null0
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
gatekeeper
shutdown
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
transport preferred none
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
transport preferred none
stopbits 1
line vty 0 4
transport preferred none
!
end

pman · ‎06-05-2022

Hi,

BGP neighbor is down between B3 and C3 because you are not advertising B3 loopback0 to C3.

option 1

B3(config-router)#router isis as30
B3(config-router)#passive-interface Loopback0

option 2

B3(config)#interface Loopback0
B3(config-if)#ip router isis as30

suggests first checking if your bgp peer is up among all the relevant routers, and only then checking the reason why routings are not received

View solution in original post

Jon Marshall · ‎06-05-2022

Do the routers have a BGP peering -

sh ip bgp summary

Is C3 advertising routers to B3 -

sh ip bgp neighbors 100.68.3.1 advertised-routes

Jon

pman · ‎06-05-2022

Hi,

BGP neighbor is down between B3 and C3 because you are not advertising B3 loopback0 to C3.

option 1

B3(config-router)#router isis as30
B3(config-router)#passive-interface Loopback0

option 2

B3(config)#interface Loopback0
B3(config-if)#ip router isis as30

suggests first checking if your bgp peer is up among all the relevant routers, and only then checking the reason why routings are not received

hfakoor222 · ‎06-05-2022

Very helpful, thank you!