Configuring appliances in a WCCP cluster has the following limitations:

  • All appliances within a cluster must be the same model and use the same software release.
  • Parameter synchronization between appliances within the cluster is not automatic. Use Command Center to manage the appliances as a group.
  • SD-WAN traffic shaping is not effective, because it relies on controlling the entire link as a unit, and none of the appliances are in a position to do this. Router QoS can be used instead.
  • The WCCP-based load-balancing algorithms do not vary dynamically with load, so achieving a good load balance can require some tuning.
  • The hash method of cache assignment is not supported. Mask assignment is the supported method.
  • While the WCCP standard allows mask lengths of 1-7 bits, the appliance supports masks of 1-6 bits.
  • Multicast service groups are not supported. Only unicast service groups are supported.
  • All routers using the same service group pair must support the same forwarding method (GRE or L2).
  • The forwarding and return method negotiated with the router must match: both must be GRE or both must be L2. Some routers do not support L2 in both directions, resulting in an error of “Router’s forward or return or assignment capability mismatch.” In this case, the service group must be configured as GRE.
  • SD-WAN VPX does not support WCCP clustering.
  • The appliance supports (and negotiates) only unweighted (equal) cache assignments. Weighted assignments are not supported.
  • Some older appliances, such as the SD-WAN 700, do not support WCCP clustering.
  • (SD-WAN 4000/5000 only) Two accelerator instances are required per interface in L2 mode. three interfaces are supported per appliance (and then only on appliances with six or more accelerator instances.)
  • (SD-WAN 4000/5000 only) WCCP control packets from the router must match one of the router IP addresses configured on the appliance for the service group. In practice, the router’s IP address for the interface that connects it to the appliance should be used. The router’s loopback IP cannot be used.

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