no ip route-cache + frame relay?

[anestis.iliadis]

Hello all,

I'm doing some ccnp frame relay labs where I'm using a router to simulate a frame relay switch. In all the configuration samples that I've read so far, including the one from cisco for the sample frame-relay switch config, they always use no ip route-cache. Even in the comprehensive guide for frame relay here http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml
they use no ip route-cache.

I've looked up route-cache here: http://www.cisco.com/en/US/docs/ios/12_3/switch/command/reference/swi_i1.html#wp1110844
and here: https://learningnetwork.cisco.com/thread/21603 but I found no references to frame relay.

Can someone explain to my why I might need to disable fast switching when I'm doing frame relay switching?

thank you,

[Giuseppe Larosa · Accepted solution]

Hello Anestis,

I agree that frame-relay switching shoud not need "no ip route-cache"

By the way the configuration of frame-relay switch america in first link you have reported does not show the no ip route-cache command.

In some of my own labs the FR switch was not a dedicated device, but it was at the same time running the role of PE node in MPLS so FR switching should work with CEF too ( that is required for MPLS operations).

Also no ip route-cache refers to OSI layer 3 operation for IPv4 protocol, and frame-relay switching is an OSI layer 2 operation performed between some interfaces of the router acting as FR switch.

Hope to help

Giuseppe

[Peter Paluch]

Hello Giuseppe,

Just to add, it is possible that the command has been added by IOS automatically. I have very often seen the no ip route-cache cef and no ip route-cache command automatically added to interfaces as soon as no ip routing has been configured on a router. As the ip route-cache is a feature exclusive to routing IP packets between interfaces, it should not affect at all how Frame Relay frames are switched (regardless whether they carry IP packets or not).

Best regards,

Peter

[anestis.iliadis]

Thank you both for the replies,

I'm sorry I just noticed now that the no ip route cache in the link i provided is only under the dialer and bvi interfaces. Not under the serial ones. Still, I've done 4 labs now from the cisco networking academy on ccnp and they all have no ip route-cache for serial interfaces whenever the router is doing frame-relay switching.

Anyhow, probably Peter is right and they were added as default. I just wanted to make sure that it has nothing to do with frame-relay switching and fast-switching and cef don't interfere or anything. Thanks for confirming that.