Cabletron Systems 9032578-05 manual Layer 4 Bridging

Appendix A: New Features Supported on Line Cards

When load balancing is implemented in a single system, the ports that attach to both incoming and outgoing interfaces must reside on -AA or T-series line cards. If the servers are load-sharing across multiple networks, ports assigned to the interfaces must also reside on -AA or T-series line cards. In Diagram 3, Client A can access the Virtual Server Address, but Client B cannot access the Virtual Server Address because Client B is connected to a non -AA line card.

However, if clients are connected through another system, as long as the final incoming and outgoing ports to the Virtual Server Address reside on -AA or T-series line cards, the clients are able to take advantage of the load-sharing feature. Client C in Diagram 3 can access the Virtual Server Address even though Client C is connected to Router B with a non -AA line card.

Layer 4 Bridging

Layer 4 bridging allows the administrator to set up a layer 3 and layer 4 “lookup” for bridged packets. Traffic that is switched at layer 2 through the SSR can apply QoS and security filters (ACLs) based on the layer 3/4 information contained in the packet. Unlike the traditional implementation, where ACLs or QoS must be applied on the router interface, you can now apply ACLs or QoS on the physical ports.

Layer 4 bridging is enabled on a per-VLAN basis. A network administrator first creates a VLAN to contain the ports that require layer 4 bridging. By enabling layer 4 bridging mode on the VLAN, the administrator can then apply ACLs or QoS on ports that are in layer 4 bridging mode. Different ACLs or QoS can be applied to ports that are in the same layer 4 bridging VLAN. Ports that are included in a layer 4 bridging VLAN must reside on -AA or T-series line cards. The system does not allow ports that are on non -AA line cards to be included in layer 4 bridging VLANs.

SmartSwitch Router User Reference Manual 365