Troubleshooting guide

1-8
Cisco Wide Area Application Services Configuration Guide
OL-26579-01
Chapter 1 Configuring Traffic Interception
Configuring Advanced WCCP Features on Routers
All ports receiving redirected traffic that are configured as members of the same WCCP service group
share the following characteristics:
• They have the same hash or mask parameters, as configured with the WAAS Central Manager (the
“Configuring or Viewing the WCCP Settings on WAEs” section on page 1-17) or the WAAS CLI
(the wccp service-number mask global configuration command).
• The WCCP Version 2 service on individual ports cannot be stopped or started individually (a WCCP
Version 2 restriction).
Configuring a Router to Support WCCP Service Groups
To direct a WCCP Version 2-enabled router to enable or disable support for a WCCP service group, use
the ip wccp global configuration command. To remove the ability of a router to control support for a
WCCP service group, use the no form of this command.
The following example shows how to enable the TCP promiscuous mode service (WCCP Version 2
services 61 and 62) on a router:
Router(config)# ip wccp 61
Router(config)# ip wccp 62
On each WAE, configure multiple router addresses in the WCCP router list, one for each router in the
service group.
WAE(config)# wccp router-list 1 10.10.10.20 10.10.10.21
Finally, you need to configure each router for WCCP interception on the inbound direction of the
appropriate interfaces, using commands similar to the following:
Router(config)# interface fa1/0.40
Router(config-subif)# ip wccp 61 redirect in
Router(config-subif)# exit
Router(config)# interface serial0
Router(config-subif)# ip wccp 62 redirect in
Router(config-subif)# exit
When a new WAE is brought online, it joins the WCCP service group. With a new WAE in the service
group, the hash tables responsible for distributing the load are changed, and traffic that previously went
to WAE1 may now go to WAE2. Flow protection must be enabled in order for WAE2 to forward packets
of already connected clients to WAE1. The end result is that all requests that belong to a single session
are processed by the same WAE. Without flow protection enabled, adding a WAE to the service group
might disconnect some of the existing clients.
When an WAE is removed from the service group, its clients are disconnected (if they reconnect, they
will reach another WAE, if one is available, or the origin file server).
WAAS supports WAE failover by reconnecting clients with other branch WAEs if a branch WAE
crashed. In the event of a crash, the branch WAE stops issuing WCCP keepalives (constant high CPU
load may also result in loss of keepalives and can also be considered a failover case). The router detects
the lack of keepalives and removes the branch WAE from the service group. The designated branch WAE
updates the WCCP configuration hash table to reflect the loss of the branch WAE and divides its buckets
among the remaining branch WAEs. A new designated lead branch WAE is elected if the crashed one
was the lead branch WAE. The client is disconnected, but subsequent connections are processed by
another branch WAE.
Once a TCP flow has been intercepted and received by a branch WAE, the failure behavior is identical
to that exhibited during nontransparent mode. For example, data center WAE and file server failure
scenarios are not handled any differently as a result of using WCCP interception.