HP ProCurve 7102dl Reference Manual page 333

SROS Command Line Interface Reference Guide Global Configuration Mode Command Set
bridge irb
Use the bridge irb command to enable integrated routing and bridging (IRB) and also allow the creation of
bridged virtual interfaces (BVIs). Use the no form of this command to disable the IRB.
Syntax Descriptions
There are no subcommands for this command.
Default Values
By default, IRB is disabled.
Functional Notes
The bridge irb must be enabled to create bridged virtual interfaces (BVI).
Once the command bridge irb is entered, the IP addresses for any interfaces connected to any bridge will
be removed. Also, the command ip address xx.xx.xx.xx.xx.xx.xx.xx will no longer be available on an
interface that is connected to the bridge.
The BVI interface must be removed before using the no bridge irb command.
For more information on BVI configuration, refer to the BVI Interface Config Command Set on page 786.
Technology Review
Integrated Routing and Bridging (IRB) allows the routing of specified protocols between network interfaces
and bridge groups. The difference between IRB and Concurrent Routing and Bridging (CRB) is that in IRB
it is possible to route IP between routed interfaces and BVIs, but with CRB the routed interfaces cannot
communicate with bridged interfaces. IRB's primary goal is to bridge all protocols and route any IP traffic
destined for the MAC address of the BVI.
The IRB handles IP packets in the following manner: When an IP packet comes into the router and it is not
destined for the MAC address, it is bridged. If the IP packet is destined for the MAC address, it is sent to
the routing engine and routed as normal. The IRB allows for PCs in the bridge to get to routed networks
and routed networks to get to the bridge. The bridge group will isolate broadcasts from other routed
interfaces.
A BVI interface can only be created when IRB is enabled and a bridge group has been defined. The BVI
interface number corresponds directly to the bridge group.
When IRB is enabled and a BVI is configured, IP network configuration is removed for all bridged
interfaces. IP traffic destined for the BVI address is delivered to the local IP stack for routing (if routing is
enabled) or management. If no BVI is configured, the behavior is the same as if IRB is not enabled.
When IRB is not enabled, a BVI cannot be created. Bridged interfaces retain their IP configuration, and IP
traffic destined for those interfaces is delivered to the local IP stack.
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