[c-nsp] IOS-XR and PBR

[Oliver Boehmer (oboehmer)]

> 
>Since we have no default routes and all backbone links are full BGP minus
>default route, I am going to assume that the second permit statement
>won't work here. Would this just get specified as any since the first
>entry would be matched for local netblocks and

sorry, 0.0.0.0/0 should be "any".. so the first line matches traffic to
your networks (and it just passes through normally and will be forwarded
according to your RIB/FIB), and the 2nd matches traffic from this customer
block to anything else, which then will be ABF'ed to your upstream.

>it would not go further in the ACL?

it actually would, so I missed a "permit ipv4 any any" catch-all at the
end of the ACL to ensure traffic from other sources is forwarded
normally.. it is a regular ACL, the ABF directives are just inserted into
it.
Need more coffee..

>These special case customers all are fed from a single 6509 to the border
>router that contains their one carrier of choice, but that border router
>contains several backbone links and each border router also having links
> to each other. I suspect that for simplifying this, we can match against
>traffic on the link coming from that 6509 to the border router.

exactly, that sounds straight-forward, just apply this inbound and you're
set..

	oli


>
>
>
>Thanks for the pointers.
>
>
>-Lee
>
>
>On Wed, Sep 10, 2014 at 11:09 PM, Oliver Boehmer (oboehmer)
><oboehmer at cisco.com> wrote:
>
>
>>
>>I am looking to setup some policy based routing on an IOS-XR router. From
>>what I understand, XR does not have PBR, but ABF. When looking at how ABF
>>works, I don¹t see how to set a next hop route (only next hop per TCP
>>port).
>
>well, you can direct any traffic matching an ACE (be it layer 3 or 4) to a
>chosen next-hop.
>
>>My question then would be, how does one accomplish this on XR? What
>>I need to do is allow a particular IP block to only have access to one of
>>our backbone carriers and not the others. We have their /24 only
>>announced
>>out the one carrier, but for outbound traffic, I want to make sure their
>>traffic remains on that carrier but also have access to our local routes
>>(all our local customers and local networks). Is this something that can
>>be
>>done with ABF
>
>Yes, it can be done, but possibly a bit more difficult:
>
>ipv4 access-list ABF
> permit CUST/24 <your-own-netblocks>
> permit CUST/24 0.0.0.0/0 <http://0.0.0.0/0> next-hop
><your-upstream-provider>
>
>not sure how your topology looks and where you would need to apply this
>forwarding rule, but the next-hop can be directly connected or resolve via
>some form of tunnel (including LDP/LSP).
>
>        oli
>
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>