WCCP and WAN optimisation via Layer 3 connection

[Andreas van Fondern]

Hi There,

I need some help with WCCP, however with Riverbeds instead of WAAS.

The topology of the set up is as follows:

WAN - R1 - LAN - L3 Switch - Riverbed

The clients reside on the WAN side and the servers reside on the LAN side.

My business wishes to enable WCCP on two separate WAN routers to the single Riverbed. One router is fuly managed service, and the other rout the is managed by the business IT team.

All the articles that I have come across talk about enabling WCCP on the router whereby the WAN optimisation appliance is directly connected to a interface router. I need to configure WCCP to a Riverbed that is connected to a subnet that is a single hop away via a Layer 3 switch.

My plan is to enable WCCP in the inbound directions on both the LAN and WAN interfaces, however my concern is that this design will mean the traffic passing through the LAN side interface will be optimised twice.

Can any one confirm if this would happen? If it could happen can it potentially be stopped by placing a "ip wccp redirect exclude out" command on the LAN interface.

Thanks is advance for your help.

[finn.poulsen]

Hi Andreas,

"ip wccp redirect exclude out" only makes sense if you have a "ip wccp redirect out"
on a L3 interface on the router.
It's purpose is to avoid redirecting an already optimised packet, comming from a L3-interface where the WAAS/Riverbed device is connected, once more.

A double redirect will, in a WAAS setup, cause the WAAS device to drop the packet, because
it suspects a routing loop... don't know what Riverbed does.

Running only with "ip wccp redirect in" on both the WAN and LAN interface will cause :

1) a packet comming in from the LAN, is supposed to be unoptimised, and will be redirected
2) a packet comming in from the WAN, is supposed to be optimised, and will also redirected
3) an IP-interface with only the WAAS/Riverbed connected should NEVER be redirected !

If you cannot isolate your WAAr/Riverbed in it's own L3 subnet (subinterface/VLAN),
and therefore have to place it in the "ordinary" LAN subnet, packets from the WAAS/Riverbed will becomes candidates for redirection (even with "ip wccp redirect in"), you'll need to use "WCCP negotiated Return", but don't know whether Riverbed supports this,

Riverbed normally uses "tunnels" on the WAN side, and this makes the WCCP setup somewhat different.
You should really consult the Riverbed documentation or their support
... or migrate to Cisco WAAS ;-)

Best regards

Finn Poulsen