Troubleshooting guide

Troubleshooting

Remove an IPv4 ACL:

(config-bgp-neighbor)#no distribute-list <ipv4 acl name> [in | out]

<ipv4 acl name> Specifies the name of the IPv4 ACL to be removed.

in Specifies to remove the inbound filter.

out Specifies to remove the outbound filter.

Clear the BGP neighbor with a soft reset and observe if the AOS device begins to receive routes. If routes

are received, then it is confirmed that the filter is the problem. Reconfigure the prefix list, route map, or

IPv4 ACL keeping in mind that the AOS device processes entries in order by sequence number and stops

as soon as it finds a match.

A prefix list or route map can also be monitored to see how it is affecting traffic by viewing the list or map

and checking the number of packets the router has matched to it. Refer to

Troubleshooting a Prefix List on

page 79 and Troubleshooting a Route Map on page 80.

If a prefix list is being used with a route map, then it is important to determine whether it is the prefix list

or the route map configuration that has the error. An entry in the prefix list that permits all routes can be

configured:

(config)#ip prefix-list <name> seq <number> permit 0.0.0.0/0 le 32

<name> Specifies the name of the prefix list.

<number> Specifies the entry's unique sequence number that determines the processing order. Lower

numbered entries are processed first. Range is 1 to 4294967294.

Clear the BGP neighbor with a soft reset and observe if the AOS device begins to receive routes. If routes

are received, then it can be concluded that the prefix list must be reconfigured. Otherwise, the route map is

the problem.

BGP Will Not Accept Routes

If it is suspected that filters are keeping the AOS device from receiving routes, compare the routes that

BGP receives from a neighbor to those it actually accepts. Enter:

#show ip bgp neighbor <ipv4 address> received-routes

#show ip bgp neighbor <ipv4 address> routes

Note any routes that are displayed when the first command is entered, but not displayed when the second

command is entered. These routes are being filtered out. Also, determine if the filter is rejecting a route by

locating the asterisk (*) in front of the network address. The absence of an asterisk means that the AOS

device considers the displayed route invalid. See

Figure 11 on page 77.

When adding an entry to a prefix list to permit all routes, the sequence number specified

should be the lower than all other entries contained within the prefix list.