How exactly does CEF determine an adjacency for a PPP peer? I know it sounds like a simple question, but...
I've had CEF disabled for a long time because I knew it did something to kill my serial PPP connection. Now I really need to enable it so voice performance will be acceptable on the LAN side and I've been trying to understand the problem. This is a 3640 with 12.4(13a), but I think I first noticed the CEF/PPP issue on an older platform with older software.
When CEF is first enabled it creates a valid adjacency for the PPP peer, but after a few minutes the adjacency becomes invalid and subsequent packets are rate-limited-punted, with the adjacency never again becoming valid. Debugging CEF gives the expected "stalled adjacency" message for each packet destined for the PPP peer.
Here is an example of the valid adjacency:
x.x.x.2/32, version 73, epoch 0, attached, connected, per-packet sharing0 packets, 0 bytes via Virtual-Access1, 2 dependencies valid adjacency 0 packets, 0 bytes switched through the prefix tmstats: external 0 packets, 0 bytes internal 0 packets, 0 bytes
Here it has become invalid:
x.x.x.2/32, version 73, epoch 0, attached, connected, per-packet sharing0 packets, 0 bytes via Virtual-Access1, 2 dependencies invalid adjacency 0 packets, 0 bytes switched through the prefix tmstats: external 0 packets, 0 bytes internal 0 packets, 0 bytes
Here is my dialer configuration:
interface Dialer0 ip address x.x.x.1 255.255.255.252 ip access-group 100 in ip accounting output-packets encapsulation ppp dialer pool 1 dialer remote-name xxxxxxxx-gateway dialer idle-timeout 0 dialer string xxx dialer load-threshold 100 either dialer vpdn dialer-group 1 no cdp enable ppp accm 0 ppp pfc local request ppp pfc remote apply ppp acfc local request ppp acfc remote apply ppp chap hostname xxxxxxxx ppp chap password 7 XXXXXXXXXXXXXXXXXXX ppp multilink ppp multilink links maximum 2
interface Serial0/0 bandwidth 56 no ip address encapsulation ppp no ip mroute-cache dialer in-band dialer pool-member 1 dialer-group 1 pulse-time 1 no cdp enable
I tried removing the access-group, vpdn dialer, and multilink configuration. None of this made any difference except that the last caused Serial0/0 to show up in the adjacencies instead of Virtual-Access1. I can disable CEF on the dialer interface and that "works" but it makes me uncomfortable to have the invalid adjacencies for the peer any everything that routes through it. Obviously I'm doing something stupid to break CEF's adjacency test (PPP does work with CEF, right?) but I can't tell what else it might be...
Dan Lanciani ddl@danlan.*com