Cisco 3845 Software Guide - Page 233

Chapter 11 Configuring Ethernet Virtual Connections (EVCs) Understanding EVC Features Table 11-2 Maximum Allowed Service Instance Configuration with and without Split Horizons Configured in Bridge Domain No group No Group 64 Split Group 0 32 Split Group 1 16 Split Group 2 16 Maximum Service Instances in the Group Group 0 - 32 16 16 Group 1 - - 16 16 Group 2 - - 16 Total Service Instances in Bridge Domain 64 64 48 64 Rewrite Operations You can use the rewrite command to modify packet VLAN tags. You can use this command to emulate traditional 802.1Q tagging, where packets enter a switch on the native VLAN and VLAN tagging properties are added on egress. You can also use the rewrite command to facilitate VLAN translation and QinQ. Enter the rewrite ingress tag pop {1 | 2} symmetric service-instance configuration mode command to specify the encapsulation adjustment to be performed on the frame ingress to the EFP. Entering pop 1 pops (removes) the outermost tag; entering pop 2 removes two outermost tags. Note The symmetric keyword is required to complete rewrite to configuration. When you enter the symmetric keyword, the egress counterpart performs the inverse action and pushes (adds) the encapsulation VLAN. You can use the symmetric keyword only with ingress rewrites and only when single VLANs are configured in encapsulation. If you configure a list of VLANs or a VLAN range or encapsulation default or encapsulation any, the symmetric keyword is not accepted for rewrite operations. The ME 3800X and ME 3600X switches support only these rewrite commands. rewrite ingress tag pop 1 symmetric rewrite ingress tag pop 2 symmetric The switch does not support rewrite commands for ingress push and translate in this release. However, you can use the rewrite ingress tag pop symmetric command to achieve translation. Possible translation combinations are 1-to-1, 1-to-2, 2-to-1, and 2-to-2. When forwarding to or from a Layer 2 port, you cannot achieve 2-to2 translation because a Layer 2 port is implicitly defined to be rewrite ingress tag pop 1 symmetric. The switch does not support egress rewrite operations beyond the second VLAN that a packet carries into a switch. Because of the egress rewrite limitation, if an EFP has a pop 2 rewrite operation at ingress, no other EFP in the same bridge domain can have a rewrite operation. See the "Global Rewrite Operation Limitation on a Switch" section on page 11-14. OL-23400-01 Cisco ME 3800X and 3600X Switch Software Configuration Guide 11-7