Source based routing??

[jonseung]

Hi,

I ran into a siutation where I had to create a static route based on the source. I enabled ip source route but I'm not sure how this should be entered into the router.

i.e I need two static routes for;

Any traffic to 0.0.0.0 from 10.0.0.0/8 to be routed to A

Any traffic to 192.0.0.0 from 10.0.0.0/8 to be routed to B

Thank you in advance for your prompt response.

[jonseung]

Hi Giuseppe,

I have IOS 12.2.50(SE3) IPSERVICE-K9.

Switch accepts all PBR related command but I just can't see IP Policy route-map statement under the respective VLAN.

I tried the same thing in my 3550 switch (same IOS level and feature set) but same result.

Very strange.

[Peter Paluch]

Hello Jon,

You will probably have to change the SDM (Switch Database Management) setting. The SDM template is used to divide the size-limited TCAM in your switch for various applications. The default "desktop" template does not reserve any TCAM space for policy-based entries and that's probably the reason why the switch does not allow you to configure it.

The SDM template can be changed in the global configuration mode using the sdm prefer TEMPLATE-NAME command and reloading the switch. You should consult this URL for details about the template names and their characteristics:

http://cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_50_se/configuration/guide/swsdm.html

Note that for IPv4, only the "access" and "routing" templates reserve a space for policy-based entries. For IPv4-and-IPv6, only the "routing" template allows the PBR. You should carefully select the template that matches your needs and leaves sufficient space for all features you currently use.

Best regards,

Peter

[jonseung]

I see what the problem is.

Catalyst 3550 series switches have hardware based forwarding, thus forwarding information is programmed in Ternary Content Addressable Memory (TCAM). In order for the TCAM to support Policy Based Routing (PBR), it should be formatted by changing the Switch Database Management (SDM) template. You must modify the SDM template, such that it supports the 144-bit Layer 3 TCAM.

In order to utilize PBR on 3550/3560, you will have to issue 'SDM prefer ...' command.

[Giuseppe Larosa]

Hello Jon,

as Peter has explained to use PBR on these multilayer switches two conditions have to be met:

IP Services image

the appropriate SDM template

the SDM template change requires a reload to be effective so you may need to ask for a maintanance time window.

Hope to help

Giuseppe

[jonseung]

Thanks again for all your help!

Have a great day.