Anyone use Cisco Policy Routing?

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1

Hi,
I'm trying to setup a platform that will send different types of packets
over different routes, theres a good example of what I'm doing at

http://www.cisco.com/warp/public/cc/pd/ibsw/ibdlsw/prodlit/dlsw5_rg.htm

under 'Directing Traffic Flows with Policy Routing'

Basically, it doesnt work, I'm on IOS 12.0(3) and not sure if its a bug or
just me.

I'm using policy routing and route-maps to identify certain types of
traffic by tcp port number using extended access-lists and then change the
next-hop.

Whats happening is that it works okay until the above access-list makes a
match, after that all packets to that IP address regardless of port number
get sent via the modified next hop.

I'm wondering if I've got
a) an IOS bug

or if

b) I need to turn off some kind of route caching/cef that works at layer 3
altho I've disabled everything I could think of on the interface

Any thoughts?

Steve

2

This does not sound like a problem with IOS, but more like a problem with
the configuration. Packets matching in your access
list will go to the designated next hop. Those failing to match will not be
discarded. These packets will take the course of the routing table.

Where are you trying to apply the route map? The interface or the routing
protocol? For what you're doing, you should apply the Route Map to an
incoming interface.

Try another matching statement with a lower precedence under your Policy.

Ex:

route-map Stephen_Policy permit 10
match ip address access_list_A
set ip next hop A.A.A.A

route-map Stephen_Policy permit 20
match ip address access_list_B
set ip next hop B.B.B.B

route-map Stephen_Policy permit 30
match ip address default_list
set ip next hop C.C.C.C

~ Clarke ~

3

This does not sound like a problem with IOS, but more like a problem with
the configuration. Packets matching in your access
list will go to the designated next hop. Those failing to match will not be
discarded. These packets will take the course of the routing table.

Where are you trying to apply the route map? The interface or the routing
protocol? For what you're doing, you should apply the Route Map to an
incoming interface.

Try another matching statement with a lower precedence under your Policy.

Ex:

route-map Stephen_Policy permit 10
match ip address access_list_A
set ip next hop A.A.A.A

route-map Stephen_Policy permit 20
match ip address access_list_B
set ip next hop B.B.B.B

route-map Stephen_Policy permit 30
match ip address default_list
set ip next hop C.C.C.C

~ Clarke ~

4

Steve,
  I've seen this problem happen w/ policy routing and CEF enabled.
You need to turn off CEF if this is happening to you. Cisco has a bug out
on this, if I can find it in my notes I'll send it.

Mark.

5

At least Gnaps -- 7:45 PM our PRI's and hardware went dead.

6

We came back up at Old Slip at about 8:55 PM EDT.

Our T1 is back too ! Life is good !

I'm going to have another beer.

Make that a scotch.

7

have you tried 12.0(7)? Many fixes to strange issues...

8

How does this apply to Cisco's Policy Routing ?

9

Stephen,

I'm wondering if I've got
a) an IOS bug

Send me the configuration and a description of what
you are trying to accomplish (ie. what packets you want
to redirect where) and I'll tell you if it's broken.

>

or if

b) I need to turn off some kind of route caching/cef that works at layer 3
altho I've disabled everything I could think of on the interface

You should *never* have to disable a switching path to make a feature
work. If you do it's a bug and please open a TAC case on it so
the problem is fixed. Cisco IOS switching paths are designed such
that if you enable a feature that is not supported in a particular
switching path then that packet is punted to the next switching path
to be handled.

Thanks,
Rodney
Escalation Engineer
Routing Protocols
Cisco Systems Inc.