Allied Telesis C613-16164-00 REV E manual Inter-VRF communication via BGP

Dynamic inter-VRF communication explained

Inter-VRF communication via BGP

Dynamic inter-VRF route leakage is achieved by making copies of BGP routes that exist in one BGP address-family associated with one VRF instance, to another BGP address-family associated with a different VRF instance.

OSFP
routerpeer
		1			Redistribute BGP
	OSPF				from VRF red FIB
			VRF
Redistribute OSPF		red					Redistribute BGP
		FIB
from VRF red FIB							from VRF blue FIB
BGP
address
family	-					VRF
red					blue
			BGP		FIB		OSPF
								2
			address
		family		-
		blue
					Redistribute OSPF			OSFP
					from VRF blue FIB			routerpeer
BGP routes copied between BGP							VRF Device
address-families to facilitate inter-VRF
communication

In the diagram above, the following is configured:

OSPF1 is configured in VRF-red, and OSPF1 contains redistribute BGP

OSPF2 is configured in VRF-blue, and OSPF2 contains redistribute BGP

BGP is configured and contains BGP address-families red and blue

Both BGP address-families contain redistribute OSPF

Then route leakage of routes from VRF red to VRF blue occurs as follows:

1.OSPF1 selects appropriate OSPF routes learned from external VRF red OSPF peer and automatically adds them to red FIB route table.

2.OSPF1 routes are imported from red FIB route table into BGP address-family red BGP route table (via the BGP redistribute OSPF command).

3.Via the route-target import command, BGP address-family red BGP routes are selected and copied into BGP address-family blue BGP route table.

4.Appropriate BGP address-family blue BGP routes are selected and automatically added to the VRF blue FIB route table.

5.OSPF2 then imports and redistributes the BGP routes (learned originally from VRF red OSPF peer) into OSPF2 from VRF blue FIB route table (via OSPF redistribute BGP command).

6.Those OSPF routes are then advertised to external VRF blue OSPF peer.

And the same process is used to leak routes from VRF blue to VRF red.

Page 20 Configure VRF-lite