[c-nsp] impact of policy based routing

[Rubens Kuhl Jr.]

It depends on whether the policy route will be only processed by the
SUP/RSP-720 or not.

Although the following text is from the Cat IOS (ISBU) not 7600 IOS
(ERBU), my understanding is it reflects what PFC3x can do and can't do
in hardware:

"The Policy Feature Card (PFC) and any Distributed Feature Cards
(DFCs) provide hardware support for policy-based routing (PBR) for
route-map sequences that use the match ip address, set ip next-hop,
and ip default next-hop PBR keywords.

When configuring PBR, follow these guidelines and restrictions:
–The PFC provides hardware support for PBR configured on a tunnel interface.
–The PFC does not provide hardware support for PBR configured with the
set ip next-hop keywords if the next hop is a tunnel interface.
–If the RP address falls within the range of a PBR ACL, traffic
addressed to the RP is policy routed in hardware instead of being
forwarded to the RP. To prevent policy routing of traffic addressed to
the RP, configure PBR ACLs to deny traffic addressed to the RP.
–Any options in Cisco IOS ACLs that provide filtering in a PBR
route-map that would cause flows to be sent to the RP to be switched
in software are ignored. For example, logging is not supported in ACEs
in Cisco IOS ACLs that provide filtering in PBR route-maps.
–PBR traffic through switching module ports where PBR is configured is
routed in software if the switching module resets. (CSCee92191)
–Any permit route-map sequence with no set statement will cause
matching traffic to be processed by the RP.  "

If you manage to keep within these boundaries, CPU load will be as if
there were no PBR at all. Otherwise, you will either eat up a
signification port of RSP720 pps capacity, or kill a SUP720.


Rubens


On Sun, Aug 10, 2008 at 11:47 PM, rendo <r3nd0 at yahoo.com> wrote:
> Hi,
>
> I'm looking for any cisco documentation or maybe your experiences regarding
> the impact of implementing policy based routing in 76xx platrform. I have a
> plan to put around 5-10 source based routing, each source goes to the same
> outgoing interface but with different IP next-hop. The projected throughput
> will be around 1 Gbps.
>
> I guess there are some impacts on CPU load and memory as well, so if anyone
> here has anything to share, it would be great.
>
> Thanks in advance.
>
> -rendo-
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