BGP Optimization options

1. BGP Optimization
Proposal

2. Network Connectivity– High Level
CE R1
4500
Site -1
VLAN-1 10.1.1.0/24
VLAN-2 10.2.2.0/24
VLAN-3 10.3.3.0/24
AS 65200
Remote Site
ISP
CE R2
4500
Site -2
VLAN-1 20.1.1.0/24
VLAN-2 20.2.2.0/24
VLAN-3 20.3.3.0/24
AS 65201
CE R3
4500
Site -3
VLAN-1 30.1.1.0/24
VLAN-2 30.2.2.0/24
VLAN-3 30.3.3.0/24
AS 65208
AS 65000
EBGP
EIGRP
* All AS Numbers and IP Addresses are symbolic

3. Control Plane – Routing Protocols
• EIGRP – Interior Gateway Routing
– Handles Local Routing Advertisements and
Neighbourship with Regional Routers
– Fully Converged and has the routing updates from
the regional sites
• BGP – Exterior Gateway Routing
– Handles External Routing Advertisements &
Neighbourship with Service Provider
– Unique Private AS’s are configured for the sites.
– Hub and Spoke Design.

4. • Sites are isolated from External Network.
– Incase of failure on the Link towards Service
Provider.
Control Plane – Routing Concerns

5. Redistributing BGP learned routes to EIGRP.
!
router eigrp 1
redistribute bgp 65200 metric 10000 100 100 100 100
!
router bgp 65200
no synchronization
bgp log-neighbor-changes
Advertising Local VLAN’s to BGP
network 10.1.1.0 mask 255.255.255.0
network 10.2.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
neighbor 52.52.52.2 remote-as 65000
no auto-summary
!
Site 1 - CE
Redistributing BGP learned routes to EIGRP.
!
router eigrp 1
redistribute bgp 65201 metric 10000 100 100 100 100
!
router bgp 65201
no synchronization
bgp log-neighbor-changes
Advertising local VLAN’s to BGP
network 20.1.1.0 mask 255.255.255.0
network 20.2.2.0 mask 255.255.255.0
network 20.3.3.0 mask 255.255.255.0
neighbor 53.53.53.2 remote-as 65000
no auto-summary
!
Site 2 - CE
Redistributing BGP learned routes to EIGRP.
!
router eigrp 1
redistribute bgp 65208 metric 10000 100 100 100 100
!
router bgp 65208
no synchronization
bgp log-neighbor-changes
Advertising local VLAN’s to BGP
network 30.1.1.0 mask 255.255.255.0
network 30.2.2.0 mask 255.255.255.0
network 30.3.3.0 mask 255.255.255.0
neighbor 54.54.54.2 remote-as 65000
no auto-summary
!
Site 3 - CE
• Unique AS’s for all sites (Hub and Spoke Design).
• Only Local networks are advertised to BGP.
Current BGP Configurations
* All AS Numbers and IP Addresses are symbolic

6. Proposed Control Plane Changes - Routing
• EIGRP
– No changes required
• BGP
– Configure all the CE routers to advertise all the
regional Networks to BGP
– AS path Pre-pending

7. Proposed Control Plane Changes - BGP
• Results
– 2 back-up paths for all the networks.
– Control over advertising networks.
– Indian admin can influence the routing decision
of other AS.
– Optimal routing as possible.

8. Proposed BGP Configurations – AS paths prepend.
• AS paths prepend.
– The only global BGP metric available to influence
the best path selection is the autonomous system
path length. By varying the length of the
autonomous system path, a BGP speaker can
influence the best path selection by a peer further
away.

9. Proposed Control Plane Changes – Task List
• Ensure the Reachability of Regional Sites through
EIGRP.
• Configure all the CE routers to advertise all the
regional Networks to BGP.
• Pre-pend respective AS number to respective
network when advertised to the neighbor.

10. Proposed Control Plane Changes– BGP AS
path prepend list.
• Access list.
– 3 standard access list matching each local site
networks
• Route-map.
– Route map prepends AS number to BGP updates
for networks that are permitted by access list.
• Apply outgoing policy.
– apply the outgoing policy route map for the
application of attributes to specific routes in BGP
peering.

11. !
router bgp 65200
no synchronization
bgp log-neighbor-changes
!--- The next lines announce all the local sites
!--- networks to BGP peers.
network 10.1.1.0 mask 255.255.255.0
network 10.2.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
network 20.1.1.0 mask 255.255.255.0
network 20.2.2.0 mask 255.255.255.0
network 20.3.3.0 mask 255.255.255.0
network 30.1.1.0 mask 255.255.255.0
network 30.2.2.0 mask 255.255.255.0
network 30.3.3.0 mask 255.255.255.0
!--- The next line configures eBGP with ISP.
neighbor 52.52.52.2 remote-as 65000
!--- This is the outgoing policy route map for
!--- prepending AS attributes to specific routes.
neighbor 52.52.52.2 route-map INDIA_NETWORKS
out
no auto-summary
!
Site 1 - CE
!
router bgp 65201
no synchronization
bgp log-neighbor-changes
!--- The next lines announce all the local sites
!--- networks to BGP peers.
network 10.1.1.0 mask 255.255.255.0
network 10.2.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
network 20.1.1.0 mask 255.255.255.0
network 20.2.2.0 mask 255.255.255.0
network 20.3.3.0 mask 255.255.255.0
network 30.1.1.0 mask 255.255.255.0
network 30.2.2.0 mask 255.255.255.0
network 30.3.3.0 mask 255.255.255.0
!--- The next line configures eBGP with ISP.
neighbor 54.54.54.2 remote-as 65000
!--- This is the outgoing policy route map for
!--- prepending AS attributes to specific routes.
neighbor 54.54.54.2 route-map INDIA_NETWORKS
out
no auto-summary
!
Site 2 - CE
!
router bgp 65208
no synchronization
bgp log-neighbor-changes
!--- The next lines announce all the local sites
!--- networks to BGP peers.
network 10.1.1.0 mask 255.255.255.0
network 10.2.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
network 20.1.1.0 mask 255.255.255.0
network 20.2.2.0 mask 255.255.255.0
network 20.3.3.0 mask 255.255.255.0
network 30.1.1.0 mask 255.255.255.0
network 30.2.2.0 mask 255.255.255.0
network 30.3.3.0 mask 255.255.255.0
!--- The next line configures eBGP with ISP.
neighbor 53.53.53.2 remote-as 65000
!--- This is the outgoing policy route map for
!--- prepending AS attributes to specific routes.
neighbor 53.53.53.2 route-map INDIA_NETWORKS
out
no auto-summary
!
Site 3 - CE
Proposed BGP Configurations – Edge Routers
* All AS Numbers and IP Addresses are symbolic

12. !--- These set the access lists.
!--- These set the access list for local networks.
ip access-list standard LOCAL
permit 10.1.1.0 0.0.0.255
permit 10.2.2.0 0.0.0.255
permit 10.3.3.0 0.0.0.255
!--- These set the access list for Site 3 site networks.
ip access-list standard Site 3
permit 20.1.1.0 0.0.0.255
permit 20.2.2.0 0.0.0.255
permit 20.3.3.0 0.0.0.255
!--- These set the access list for Site 2 site networks.
ip access-list standard Site 2
permit 30.1.1.0 0.0.0.255
permit 30.2.2.0 0.0.0.255
permit 30.3.3.0 0.0.0.255
!
Site 1 - CE
!--- These set the access lists.
!--- These set the access list for local networks.
ip access-list standard LOCAL
permit 30.1.1.0 0.0.0.255
permit 30.2.2.0 0.0.0.255
permit 30.3.3.0 0.0.0.255
!--- These set the access list for Site 3 site networks.
ip access-list standard Site 3
permit 20.1.1.0 0.0.0.255
permit 20.2.2.0 0.0.0.255
permit 20.3.3.0 0.0.0.255
!--- These set the access list for Site 1 site networks.
ip access-list standard Site 1
permit 10.1.1.0 0.0.0.255
permit 10.2.2.0 0.0.0.255
permit 10.3.3.0 0.0.0.255
!
Site 2 - CE
!--- These set the access lists.
!--- These set the access list for local networks.
ip access-list standard LOCAL
permit 20.1.1.0 0.0.0.255
permit 20.2.2.0 0.0.0.255
permit 20.3.3.0 0.0.0.255
!--- These set the access list for Site 2 site networks.
ip access-list standard Site 2
permit 30.1.1.0 0.0.0.255
permit 30.2.2.0 0.0.0.255
permit 30.3.3.0 0.0.0.255
!--- These set the access list for Site 1 site networks.
ip access-list standard Site 1
permit 10.1.1.0 0.0.0.255
permit 10.2.2.0 0.0.0.255
permit 10.3.3.0 0.0.0.255
!
Site 3 - CE
Proposed BGP Configurations – Edge Routers
* All AS Numbers and IP Addresses are symbolic

13. !--- These set the route-map.
!--- Here, the route map not prepends AS to BGP
!--- updates for networks that are permitted by
!--- access list LOCAL.
!
route-map INDIA_NETWORKS permit 10
match ip address LOCAL
!
!--- Here, the route map prepends AS 65200 (local) &
!--- 65208 (Site 3 AS) to BGP updates for networks
!--- that are permitted by access list Site 3.
!
route-map INDIA_NETWORKS permit 20
match ip address Site 3
set as-path prepend 65200 65208 !–making least preference
!
!--- Here, the route map prepends AS 65200 (local) &
!--- 65201 (Site 2 AS) to BGP updates for networks
!--- that are permitted by access list Site 2.
!
route-map INDIA_NETWORKS permit 30
match ip address Site 2
set as-path prepend 65200 65201 !–making least preference
!
Site 1 - CE
!--- These set the route-map.
!--- Here, the route map not prepends AS to BGP
!--- updates for networks that are permitted by
!--- access list LOCAL.
!
route-map INDIA_NETWORKS permit 10
match ip address LOCAL
!
!--- Here, the route map prepends AS 65208 (Site 3
!--- AS) to BGP updates for networks that are
!--- permitted by access list Site 3.
!
route-map INDIA_NETWORKS permit 20
match ip address Site 3
set as-path prepend 65208
!
!--- Here, the route map prepends AS 65200 (Site 1 !--
- AS) to BGP updates for networks that are
!--- permitted by access list Site 1.
!
route-map INDIA_NETWORKS permit 30
match ip address Site 1
set as-path prepend 65200
!
Site 2 - CE
!--- These set the route-map.
!--- Here, the route map not prepends AS to BGP
!--- updates for networks that are permitted by
!--- access list LOCAL.
!
route-map INDIA_NETWORKS permit 10
match ip address LOCAL
!
!--- Here, the route map prepends AS 65201 (Site 2
!--- AS) to BGP updates for networks that are
!--- permitted by access list Site 2.
!
route-map INDIA_NETWORKS permit 20
match ip address Site 2
set as-path prepend 65201
!
!--- Here, the route map prepends AS 65208 (local) &
!--- 65200 (Site 1 AS) to BGP updates for networks
!--- that are permitted by access list Site 1.
!
route-map INDIA_NETWORKS permit 30
match ip address Site 1
set as-path prepend 65208 65200 !–making least preference
!
Site 3 - CE
Proposed BGP Configurations – Edge Routers
* All AS Numbers and IP Addresses are symbolic

14. Remote Site#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 0.0.0.0 0 32768 i
*> 10.1.1.0/24 51.51.51.2 0 65000 65200 i
*> 10.2.2.0/24 51.51.51.2 0 65000 65200 i
*> 10.3.3.0/24 51.51.51.2 0 65000 65200 i
*> 20.1.1.0/24 51.51.51.2 0 65000 65208 i
*> 20.2.2.0/24 51.51.51.2 0 65000 65208 i
*> 20.3.3.0/24 51.51.51.2 0 65000 65208 i
*> 30.1.1.0/24 51.51.51.2 0 65000 65201 i
*> 30.2.2.0/24 51.51.51.2 0 65000 65201 i
*> 30.3.3.0/24 51.51.51.2 0 65000 65201 i
Remote Site#
Remote Site#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 0.0.0.0 0 32768 i
*> 10.1.1.0/24 51.51.51.2 0 65000 65200 i
*> 10.2.2.0/24 51.51.51.2 0 65000 65200 i
*> 10.3.3.0/24 51.51.51.2 0 65000 65200 i
*> 20.1.1.0/24 51.51.51.2 0 65000 65208 i
*> 20.2.2.0/24 51.51.51.2 0 65000 65208 i
*> 20.3.3.0/24 51.51.51.2 0 65000 65208 i
*> 30.1.1.0/24 51.51.51.2 0 65000 65208 65201 i
*> 30.2.2.0/24 51.51.51.2 0 65000 65208 65201 i
*> 30.3.3.0/24 51.51.51.2 0 65000 65208 65201
Remote Site#
Remote Site#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 0.0.0.0 0 32768 i
*> 10.1.1.0/24 51.51.51.2 0 65000 65200 i
*> 10.2.2.0/24 51.51.51.2 0 65000 65200 i
*> 10.3.3.0/24 51.51.51.2 0 65000 65200 i
*> 20.1.1.0/24 51.51.51.2 0 65000 65200 65200 65208 i
*> 20.2.2.0/24 51.51.51.2 0 65000 65200 65200 65208 i
*> 20.3.3.0/24 51.51.51.2 0 65000 65200 65200 65208 i
*> 30.1.1.0/24 51.51.51.2 0 65000 65200 65200 65201 i
*> 30.2.2.0/24 51.51.51.2 0 65000 65200 65200 65201 i
*> 30.3.3.0/24 51.51.51.2 0 65000 65200 65200 65201
Remote Site#
All WAN Links Are UP
Site 2 WAN Link Is DOWN Site 2 & Site 3 WAN Links Are DOWN
Appropriate AS Numbers
Prepended AS Numbers
Prepended AS Numbers
Proposed BGP Configurations – Results
* All AS Numbers and IP Addresses are symbolic

15. Proposed BGP Configurations – Results
• Results
– 2 back-up paths for all the networks.
• 3 sites are advertising all the local networks to BGP
– Control over advertising networks.
• AS numbers are indicating the original sites and transiting
paths
– Indian admin can influence the routing decision of
other AS.
• Remote sites are depending on our advertising AS attribute
for selecting the best path.
– Optimal routing as possible.