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Dynamic inter-VRF communication explained
Page 20 | Configure VRF-lite
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.
VRF Device
Redistribute BGP
from VRF red FIB
Redistribute OSPF
from VRF red FIB
Redistribute BGP
from VRF blue FIB
Redistribute OSPF
from VRF blue FIB
BGP
address-
family
blue
VRF
blue
FIB
OSPF 2
BGP
address-
family
red
OSPF 1
BGP routes copied between BGP
address-families to facilitate inter-VRF
communication
OSFP peer
router
OSFP peer
router
VRF
red
FIB
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 b
lue to VRF red.