16-17 debug ip bgp updates access-list-number out

16-17 debug ip bgp updates access-list-number out

Syntax Description:

• neighbor-ip-address ” BGP neighbor's IP address.

• access-list-number ” IP access list number.

Purpose: To debug BGP updates. The IP access list number can be in the range 1 to 199 or 1300 to 2699.

Cisco IOS Software Release: 10.0

Example 1: Debug All BGP Updates

In Figure 16-4, Router A is advertising four prefixes to Router B, and Router B is advertising four prefixes to Router A. Debug all the updates on Router B.

Figure 16-4. Debug All Updates from a Neighbor

 Router A  interface loopback 1   ip address 199.172.1.1 255.255.255.0   !   interface loopback 2   ip address 199.172.2.1 255.255.255.0   !   interface loopback 3   ip address 199.172.3.1 255.255.255.0   !   interface loopback 4   ip address 199.172.4.1 255.255.255.0   !   router bgp 1   network 199.172.1.0   network 199.172.2.0   network 199.172.3.0   network 199.172.4.0   neighbor 172.17.1.1 remote-as 2   ___________________________________________________________________________  Router B  interface loopback 1   ip address 200.1.1.1 255.255.255.0   !   interface loopback 2   ip address 200.1.2.1 255.255.255.0   !   interface loopback 3   ip address 200.1.3.1 255.255.255.0   !   interface loopback 4   ip address 200.1.4.1 255.255.255.0   !   router bgp 2   network 200.1.1.0   network 200.1.2.0   network 200.1.3.0   network 200.1.4.0   neighbor 172.17.1.2 remote-as 1  rtrB#  debug ip bgp updates  BGP updates debugging is on rtrB#  clear ip bgp *  2d03h: BGP(0): 172.17.1.2 send UPDATE (format) 200.1.1.0/24, next 172.17.1.1,  metric 0, path 2d03h: BGP(0): 172.17.1.2 send UPDATE (prepend, chgflags: 0x208) 200.1.2.0/24,  next 172.17.1.1, metric 0, path 2d03h: BGP(0): 172.17.1.2 send UPDATE (prepend, chgflags: 0x208) 200.1.3.0/24,  next 172.17.1.1, metric 0, path 2d03h: BGP(0): 172.17.1.2 send UPDATE (prepend, chgflags: 0x208) 200.1.4.0/24,  next 172.17.1.1, metric 0, path 2d03h: BGP(0): 172.17.1.2 1 updates enqueued (average=64, maximum=64) 2d03h: BGP(0): 172.17.1.2 update run completed, afi 0, ran for 0ms, neighbor  version 0, start version 5, throttled to 5 2d03h: BGP(0): 172.17.1.2 rcvd UPDATE w/ attr: nexthop 172.17.1.2, origin i,  metric 0, path 1 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.1.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.2.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.3.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.4.0/24 

Example 2: Debug Input Updates

Debug BGP updates on Router B for routes received from Router A.

 rtrB#  debug ip bgp updates in  BGP updates debugging is on (inbound) rtrb#  clear ip bgp *  2d03h: BGP(0): 172.17.1.2 rcvd UPDATE w/ attr: nexthop 172.17.1.2, origin i,  metric 0, path 1 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.1.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.2.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.3.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.4.0/24 

Example 3: Debug Output Updates for Specific Prefixes Sent to All BGP Neighbors

Debug BGP updates on Router B for local prefixes 200.1.2.0 and 200.1.3.2:

 Router B  access-list 1 permit 200.1.2.0 0.0.1.255  rtrB#  debug ip bgp updates 1 out  BGP updates debugging is on for access list 1 (outbound) rtrB#  clear ip bgp *  2d03h: BGP(0): nettable_walker 200.1.2.0/24 route sourced locally 2d03h: BGP(0): nettable_walker 200.1.3.0/24 route sourced locally 2d03h: BGP(0): 172.17.1.2 send UPDATE (prepend, chgflags: 0x208) 200.1.2.0/24,  next 172.17.1.1, metric 0, path 2d03h: BGP(0): 172.17.1.2 send UPDATE (prepend, chgflags: 0x208) 200.1.3.0/24,  next 172.17.1.1, metric 0, path 

Example 4: Debug Input Updates for Specific Prefixes Received from a Specific BGP Neighbor

Debug updates for prefixes 199.172.2.0 and 199.172.3.0 received from Router A:

 Router B  access-list 2 permit 199.172.2.0 0.0.1.255  rtrB#  debug ip bgp in 172.17.1.2 updates 2  BGP updates debugging is on for access list 2 for neighbor 172.17.1.2 (inbound) rtrB#  clear ip bgp *  p2# 2d03h: BGP(0): 172.17.1.2 rcvd UPDATE w/ attr: nexthop 172.17.1.2, origin i,  metric 0, path 1 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.2.0/24 2d03h: BGP(0): 172.17.1.2 rcvd 199.172.3.0/24