WAAS redirection methods

[mmorris11]

I have been reading the WAAS config guide and quick config guide and trying to come up with a good understanding of the WAE and router connection methods. The WCCP config in the QCG says this:

d. Enable WCCP service 61 on the inbound direction, and enable WCCP service 62 on the outbound

direction of fa1/0.40.

Core-Router1(config-subif)# ip wccp 61 redirect in

Core-Router1(config-subif)# ip wccp 62 redirect out

e. To avoid redirection loops, configure the subinterface where Core-WAE1 will connect to

Core-Router1. To avoid a routing loop, Core-WAE1 must not be attached to the same segment

(subnet) as the interface on Core-Router1 that is performing the redirection. Make sure that you have

a tertiary interface (a separate physical interface) or a subinterface (off the router?s LAN port) from

which Core-WAE1 connects. In the following example, a subinterface is being used:

Core-Router1(config-subif)# interface fa1/0.41

I find this sort of confusing. I am not sure I understand the significance of the distinction between "redirection loop" and "routing loop" and why the two subinterfaces are needed. THoughts? Also, does anyone have any thoughts as to when it is best to use the various types of redirections for the WAAS? Meaning, when is it best to use WCCP? PBR?

[Zach Seils]

Mike,

The need for a separate WAE VLAN is due to the L3/L4 transparency of our solution. Since optimized connections use the original src/dst IP addresses and ports, we need some way to tell the WCCP-enabled router not to re-intercept optimized traffic. We do this by placing the WAE's on a dedicated VLAN and excluding that VLAN from WCCP interception.

Between WCCP and PBR, WCCP is the preferred interception mechanism. PBR is typically only used when WCCP is not available (hardware/software support, SP-managed routers, etc.).

Zach

[adegany]

WAAS is optimizing traffic transparently to the IP and TCP layers, this means that after optimization, original IP and TCP header information is preserved, just the payload is different.

Due to this transparent operation you cannot, at this point, have the WAE send the optimized traffic to the router directly from the same LAN segment where the clients are, to prevent redirection loops (refers to WCCP redirection, not routing)