Note
•
If the dmz-link bandwidth value is not known for any one of the multipaths (eBGP or iBGP), the
dmz-link value for all multipaths including the best path is not downloaded to routing information
base (RIB).
•
The dmz-link bandwidth value of iBGP multipath is not considered during aggregation.
•
The route that is advertised with aggregate value can be best path or add-path.
•
Add-path does not qualify for DMZ link bandwidth aggregation as next hop is preserved. Configuring
next-hop-self for add-path is not supported.
•
For VPNv4 and VPNv6 afi, if dmz link-bandwidth value is configured using outbound route-policy,
specify the route table or use the additive keyword. Else, this will lead to routes not imported on
the receiving end of the peer.
extcommunity-set bandwidth dmz_ext
1:8000
end-set
!
route-policy dmz_rp_vpn
set extcommunity bandwidth dmz_ext additive <<< 'additive' keyword.
pass
end-policy
Example
Consider two routers Router 1 and Router 2 that are connected to internal routers in a network. Router 1
advertises a bandwidth of 50 and 20 from two different ISPs. Router 2 advertises a bandwidth of 60 and 30
from two different ISPs. With the best-path algorithm, Router 1 advertises a bandwidth of 50 and Router 2
advertises a bandwidth of 60 to the internal routers. This reduces traffic flow. But by aggregating the bandwidth,
Router 1 advertises a bandwidth of 70 (50 + 20) and Router 2 advertises a bandwidth of 90 (60 + 30). This
increases the traffic flow.
Configuring BGP DMZ Aggregate Bandwidth: Example
This is a sample configuration for Border Gateway Protocol Demilitarized Zone (BGP DMZ) link bandwidth.
Consider the topology, R1---(iBGP)---R2---(iBGP)---R3:
1
On R1:
bgp: prefix p/n has:
path 1(bestpath) with LB value 100
path 2(ebgp multipath) with LB value 30
path 3(ebgp multipath) with LB value 50
When best path is advertised to R2, send aggregated dmz-link bandwidth value of 180; aggregated value
of paths 1, 2 and 3.
2
On R2:
bgp: prefix p/n has:
path 1(bestpath) with LB value 60
path 2(ebgp multipath) with LB value 200
path 3(ebgp multipath) with LB value 50
When best path is advertised to R3, send aggregated dmz-link bandwidth value of 310; aggregated value
of paths 1, 2 and 3.
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
38
Implementing BGP
BGP DMZ Aggregate Bandwidth
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