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3560 Policy routing

grexory
Level 1
Level 1

Hi,

I'm having a bad time configuring policy based routing on a Cisco 3560.. i've got tons of experience with route-maps on routers, but i've never put one on an SVI before...

since i've had the problems i've mocked this exact scenario up..

http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a00802135d3.shtml

the only difference is that its a 3560 and not a 3550.... For some strange reason the only traffic which gets policy routed is broadcast traffic, everything else gets ignored... I cannot work out why,

If I replace the switch with a router, and use the exact same route maps/ACLs/etc but with physical routed interfaces, it works fine....

Any ideas??

6 Replies 6

mheusinger
Level 10
Level 10

Hi,

there are a number of restrictions for PBR on a 3560, which might apply in your case:

To use PBR, you must first enable the routing template by using the sdm prefer routing global configuration command. PBR is not supported with the VLAN or default template. For more information on the SDM templates, see Chapter 7, "Configuring SDM Templates."

•VRF and PBR are mutually-exclusive on a switch interface. You cannot enable VRF when PBR is enabled on an interface. In contrast, you cannot enable PBR when VRF is enabled on an interface.

•The number of TCAM entries used by PBR depends on the route map itself, the ACLs used, and the order of the ACLs and route-map entries.

•Policy-based routing based on packet length, IP precedence and TOS, set interface, set default next hop, or set default interface are not supported. Policy maps with no valid set actions or with set action set to Don't Fragment are not supported.

From "Configuring Policy-Based Routing"

http://www.cisco.com/en/US/products/hw/switches/ps5528/products_configuration_guide_chapter09186a0080509b84.html#wp1228588

Regards, Martin

Hi,

Thanks for the reply,

I have configured the switch for sdm routing, (it doesn';t allow route maps to be configured otherwise)

I've read all of this before posting here... and cannot figure out the problem i'm having..

The route-map doesn't match anything other than broadcast traffic for some reason, even if I set the ACL to any any,

and again, if I copy the exact same config to a router, it works fine..

I've logged this with a support company, who've looked at what im doing and its simple and fine and should work..

i've observed another strange thing.

When the route-map sets the next hop to the router which is directly connected, (to force traffic) nothing happens and the route-map doesn't work..

If I unplug the interface the route-map is using for its next-hop (the next-hop router)

the route-map starts matching the packets, but denying them to be PBRd because the next hop is null (obviously, I unplugged it)

The moment I plug the interface back in the route-map stops working..

Hi

I'm having the exact same issue on a 3550. Did you manage to find a solution for this?

Thanks

Hi, if CEF is enabled on the interface you wont be able to policy-route and CEF and policy based routing aren?t supported together.

Well, this is what I glean from this article :-)

http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a008008002e.html

HTH

Hello Guys,

Did you manage to find a solution to this problem. I have noticed the same behavior on my 3560 with PBR. Only the broadcast traffic matched the policy.

cheers

Ankit

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