Layer 2 Bridging Interfaces Overview
Bridging operates at Layer 2 of the OSI reference model while routing operates at Layer 3. A set of logical ports configured for bridging can be said to constitute a bridging domain.
A bridging domain can be created by configuring a routing instance
and specifying the instance-type as bridge
.
Integrated routing and bridging (IRB) is the ability to:
Route a packet if the destination MAC address is the MAC address of the router and the packet
ethertype
is IPv4, IPv6, or MPLS.Switch all multicast and broadcast packets within a bridging domain at layer 2.
Route a copy of the packet if the destination MAC address is a multicast address and the
ethertype
is IPv4 or IPv6.Switch all other unicast packets at Layer 2.
Handle supported Layer 2 control packets such as STP and LACP.
Handle supported Layer 3 control packets such as OSPF and RIP.