WCCP Tab
Configuration > Networking > WCCP
Use this tab to view, edit, and delete WCCP Service Groups.
Web Cache Communications Protocol (WCCP) supports the redirection of any TCP or UDP connections to appliances participating in WCCP Service Groups. The appliance intercepts only those packets that have been redirected to it. The appliance optimizes traffic flows that the Route Policy tunnelizes. The appliance forwards all other traffic as pass-through or pass-through-unshaped, as per the Route Policy.
WCCP Edit Row
Use this page to view, edit, and delete WCCP Service Groups. For the Service Groups to be active, you must select Enable WCCP. Additionally, the appliance should always be connected to an interface/VLAN that does not have redirection enabled—preferably a separate interface/VLAN would be provided for the appliance. If the appliance uses auto-optimization, WCCP redirection must also be applied on the uplinks of the router or L3 switch to the core/WAN.
WCCP Settings
| Field | Description |
|---|---|
| Admin | Values are up and down. The default is up. |
| Advanced Settings | You can only configure these options directly on the appliance. |
| Compatibility Mode | Select the appropriate option for your router. If a WCCP group is peering with a router running Nexus OS, the appliance must adjust its WCCP protocol packets to be compatible. By default, the appliance is IOS-compatible. |
| Forwarding Method | Also known as the Redirect Method. Packet redirection is the process of forwarding packets from the router or L3 switch to the appliance. The router or L3 switch intercepts the packet and forwards it to the appliance for optimization. The two methods of redirecting packets are Generic Route Encapsulation (GRE) and L2 redirection. either allows the appliance and the router to negotiate the best option. You always should select either. During protocol negotiation, if the router offers both GRE and L2 as redirection methods, the appliance will automatically select L2. GRE (Layer 3 Generic Routing Encapsulation) allows packets to reach the appliance even if there are other routers in the path between the forwarding router and the appliance. At high traffic loads, this option might cause high CPU utilization on some Cisco platforms. L2 (Layer-2) redirection takes advantage of internal switching hardware that either partially or fully implements the WCCP traffic interception and redirection functions at Layer 2. Layer-2 redirection requires that the appliance and router be on the same subnet. It is also recommended that the appliance be given a separate subnet to avoid pass-through traffic from being redirected back to the appliance and causing a redirection/Layer-3 loop. |
| Group ID | Refers to the Service Group ID. |
| Interface | Default value is wan0. |
| Oper Status | Common states: INIT – Initializing or down. ACTIVE – This indicates that the protocol is established and the router has assigned hash/mask buckets to this appliance. BACKUP – This indicates that the protocol is established, but the router has not assigned any hash/mask buckets to this appliance. This might be caused by using a Weight of 0. Designated – This state (in addition to Active/Backup) indicates that the appliance is the designated web-cache for the group. The designator communicates with the router(s) to assign hash/mask assignments. When there is more than one appliance in a group, the appliance with the lowest IP becomes the designator for that group. |
| Protocol | Although many more protocols are supported, generally TCP and UDP are the focus. For troubleshooting, you might consider adding a group for ICMP as well. |
| Router IP | IP address of the WCCP router. For Layer 2 redirection, use the physical IP address of the interface that is directly connected to the appliance. For Layer 3 redirection, consider using a loopback IP. It is not recommended to use VRRP or HSRP IPs as router IPs. |
Service Group Advanced Settings
| Field | Description |
|---|---|
| Assignment Detail | This field can be used to customize hash or mask values. If you have only one appliance, or if you are using route-map or subnet sharing to tunnelize, use the default LAN-ingress setting. WAN-ingress and LAN-ingress are not applicable if there is only one active appliance. WAN-ingress and LAN-ingress are also not applicable if you are using route-map or subnet sharing to tunnelize. If there is more than one active appliance and you are using TCP-IP auto-optimization: Use LAN-ingress for WCCP groups that are used to redirect outbound traffic. Use WAN-ingress for WCCP groups that are used to redirect inbound traffic. This ensures that a connection will go through the same appliance in both inbound and outbound directions and avoid asymmetry. custom provides granular control of the distribution of flows. Contact Support for assistance. |
| Assignment Method | Determines how redirected packets are distributed between the devices in a Service Group, effectively providing load balancing among the devices. The options are: either, which enables the appliance and router to negotiate the best method for assignment. This is preferred. If the router offers both hash and mask methods, the appliance will select the mask assignment method. hash, for hash table assignment. mask, for mask/value sets assignment. |
| Force L2 Return | Generally is not selected. Normally, all Layer-3 redirected traffic that is not optimized (that is, it is pass-through) is returned back to the WCCP router as GRE (L3 return). Processing returned GRE traffic can create additional CPU overhead on the WCCP router. Force L2 Return can be used to override default behavior and route pass-through traffic back to the appliance’s next hop router, which might or might not be the WCCP router. Use caution, as this could create a Layer 3 loop, if L2 returned traffic gets redirected back to the appliance by the WCCP router. |
| Password | This field is optional. |
| Priority | The lowest priority is 0, and the default value is 128. Only change this setting from the default if an interface has multiple WCCP service groups defined for the same protocol (for example, TCP) and you wish to specify which service group to use. |
| Weight | The default value is 100. You can use this to influence WCCP hash/mask assignments for individual appliances when more than one appliance is in a cluster. For Active/Backup appliance configuration, use a Weight of 0 on the backup appliance. |
The Hash and Mask areas are accessible only when you select custom in the Assignment Detail field.