The Advantages and Disadvantages of WCCP
Physical in-path deployments require less initial and ongoing configuration and maintenance than out-of-path or virtual in-path deployments. This is because physical in-path SteelHeads are placed at the points in your network where data already flows. Thus, with in-path deployments you do not need to alter your existing network infrastructure.
For information about physical in-path deployments, see
Physical In-Path Deployments.
Virtual in-path techniques, such as WCCP, require more time to configure because the network infrastructure must be configured to redirect traffic to the SteelHeads.
WCCP also has the following advantages:
No rewiring required - You do not need to move any wires during installation. At large sites with multiple active links, you can adjust wiring by moving individual links, one at a time, through the SteelHeads.An option when no other is available - At sites where a physical in-path deployment is not possible, WCCP might achieve the integration you need. For example, if your site has a WAN link terminating directly into a large access switch, there is no place to install a physical in-path SteelHead. WCCP has the following disadvantages:
Network design changes required -WCCP deployments with multiple routers can require significant network changes (for example, spanning VLANs and GRE tunnels).Hardware and IOS upgrades required - To avoid hardware limitations and IOS issues, you must keep the Cisco platform and IOS revisions at the current minimum recommended levels. Otherwise, it might be impossible to create a stable deployment, regardless of how you configure the SteelHead. For future IOS feature planning you must consider compatibility with WCCP.Additional evaluation overhead - It can take more time to evaluate the integration of the SteelHeads. This is in addition to evaluating SteelHead performance gains. You might need Riverbed Professional Services to test and perform network infrastructure upgrades before any optimization can be performed. This is especially true when WCCP is deployed at numerous sites.Additional configuration management - You must create access control lists and manage them on an ongoing basis. At small sites, it might be feasible to redirect all traffic to the SteelHeads. However, at larger sites, access control lists might be required to ensure that traffic that cannot be optimized (for example, LAN-to-LAN traffic) is not sent to the SteelHeads.GRE encapsulation - If your network design does not support the presence of the SteelHeads and the Cisco router or switch interface in a common subnet, you must use GRE encapsulation for forwarding packets. SteelHeads can accommodate the subsequent extra performance utilization, but your existing router or switch might experience large resource utilization.