FamFeld,
Integrated Routing and Bridging (IRB) is the mechanism for which frames outside the local segment are able to be routed via combining Bridging and Routing capabilities into a device. IRB allows the router to configure a layer 3 interface (or IRB groups in some vendors) in a layer 2 domain to allow frames in the segment to exit through the router.
Let's imagine an example where a
router needs to connect a layer 2 segment to the Internet. A topology to represent the role of an IRB interface would be as follows:
PCA (100.0.0.123/24) ----
SWA----irb.100---
RouterA ----- Internet (8.8.8.8)
In this case, SWA has VLAN 100 created, with multiple hosts connected to it as access ports. Traffic going to the router belongs to VLAN 100 segment. Local communication is governed by layer 2 rules (ARPing and finding the encapsulation information to forward the frames to local Ethernet-enabled devices in the segment), but whenever the 100.0.0.123 PCA wants to communicate outside its local subnet, it needs routing, for this,
RouterA will receive the traffic on
irb.100 interface, verify the destination IP header and route the packet according to its routing information base.
This is also called Brdige [Virtual|Domain] Interface (BVI or BDI) in other vendors, but is essentially the same: In a router, connecting a layer 2 domain to the 'outside world' - routing, since routers usually don't use 'VLAN interfaces' for this purpose.
HTH,
Elvin
Original Message:
Sent: 12-04-2020 15:43
From: Unknown User
Subject: IRB
Would someone be able to give me a general description of what is an IRB and what it is used for and how it is configured? Maybe direct me to some literature explaining IRBs.
Would be much appreciated.
FamFeld