NetworkTalk & BGP

B.2.c) Ebgp setup between RT-A and ISP-D-Link1 upstream link.

1. Ebgp session with ISP-D-Link1 upstream link:

router bgp 1000
bgp log-neighbor-changes
neighbor 40.40.40.1 remote-as 500
neighbor 40.40.40.1 description ISP-D-link1-Ebgp-Session
neighbor 40.40.40.1 version 4
!
address-family ipv4
neighbor 40.40.40.1 activate
neighbor 40.40.40.1 send-community both
neighbor 40.40.40.1 route-map AS-500-Link1-INCOMING in
neighbor 40.40.40.1 route-map AS-500-Link1-OUTGOING out

2. Route-map for downloading full routing table from ISP-D-Link1 Ebgp neighbor

ip as-path access-list 1 permit ^500_
route-map AS-500-Link1-INCOMING permit 10
match as-path 1

3. As a result:

RT-A#sh ip bgp summary
BGP router identifier 10.10.193.62, local AS number 1000
BGP table version is 39291422, main routing table version 39291422
370663 network entries using 47444864 bytes of memory
1092561 path entries using 56813172 bytes of memory
304438/61608 BGP path/bestpath attribute entries using 37750312 bytes of memory
110109 BGP AS-PATH entries using 4018076 bytes of memory
519 BGP community entries using 43932 bytes of memory
2 BGP extended community entries using 48 bytes of memory
610 BGP route-map cache entries using 21960 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 146092364 total bytes of memory
BGP activity 1319857/949194 prefixes, 21673871/20581310 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
11.11.225.2 4 2000 48730 54661 39291422 0 0 2w3d 5
11.11.226.27 4 1000 138188 296718 39291422 0 0 1d00h 419918
40.40.40.1 4 500 68695 192 39291422 0 0 6d20h 419907
40.40.40.5 4 500 431797 6265 39291422 0 0 1d23h 419981

RT-A#sh ip bgp neighbors 40.40.40.1 routes
BGP table version is 73414700, local router ID is 10.10.193.62
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.0.4.0/22 40.40.40.1 13 0 500 174 7545 7545 7545 7545 7545 56203 i
*> 1.5.0.0/16 40.40.40.1 1 0 500 3356 4725 i
*> 1.9.0.0/16 40.40.40.1 1 0 500 6453 4788 i
*> 1.11.0.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.8.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.16.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.24.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.32.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.40.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.48.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.56.0/21 40.40.40.1 4 0 500 2914 9318 38091 18313 i
*> 1.11.64.0/21 40.40.40.1 4 0 500 2914 9318 38091 i
*> 1.11.72.0/21 40.40.40.1 4 0 500 2914 9318 38091 i
*> 1.11.80.0/21 40.40.40.1 4 0 500 2914 9318 38091 i
*> 1.11.88.0/21 40.40.40.1 4 0 500 2914 9318 38091 i
*> 1.11.128.0/17 40.40.40.1 4 0 500 2914 9318 38091 17839 i
*> 1.12.0.0/24 40.40.40.1 35 0 500 1239 4837 4808 17431 18245 i
*> 1.12.0.0/14 40.40.40.1 63 0 500 4134 4847 18245 i
*> 1.12.1.0/24 40.40.40.1 63 0 500 4134 4847 18245 i
*> 1.21.0.0/16 40.40.40.1 4 0 500 2914 2519 i
*> 1.22.0.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.4.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.6.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.8.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.12.0/23 40.40.40.1 1 0 500 3356 9498 45528 i
*> 1.22.14.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.16.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.18.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.20.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.24.0/24 40.40.40.1 1 0 500 3356 15412 18101 45528 i
*> 1.22.24.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.28.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.30.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.32.0/23 40.40.40.1 1 0 500 1273 37986 24186 45528 i
*> 1.22.36.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.38.0/23 40.40.40.1 1 0 500 6453 4755 45528 i
*> 1.22.40.0/23 40.40.40.1 1 0 500 1273 37986 24186 45528 i

4. Route-maps for advertising ISP-A’s prefixes:

Note: We need to be careful about the permit number.

The lowest number in the route-map will be used to advertise ZONE-C customer which have a different as-number than ISP-A.

 Table B-5

4.1) Zone_C ingress traffic: ISP-D-Link1 Ebgp neighbor as secondary backup link:

 ip as-path access-list 3 permit ^2000_
route-map AS-500-Link1-OUTGOING permit 10
match as-path 3
set community 500:90

4.2) Zone_D_E ingress traffic: ISP-D-Link1 Ebgp neighbor as primary link:

ip prefix-list ZONE_D_E seq 30 permit 10.10.10.0/24
ip prefix-list ZONE_D_E seq 40 permit 10.10.10.0/24
ip prefix-list ZONE_D_E seq 50 permit 10.10.10.0/24
ip prefix-list ZONE_D_E seq 60 permit 11.11.229.0/24
route-map AS-500-Link1-OUTGOING permit 20
match ip address prefix-list ZONE_D_E

4.3) Zone_G ingress traffic: ISP-D-Link1 Ebgp neighbor as 2nd backup link:

ip prefix-list ZONE_G seq 40 permit 11.11.230.0/24
ip prefix-list ZONE_G seq 50 permit 11.11.231.0/24

ip prefix-list ZONE_G seq 130 permit 11.11.238.0/24
ip prefix-list ZONE_G seq 140 permit 11.11.239.0/24
ip prefix-list ZONE_G seq 200 permit 10.10.192.0/24
ip prefix-list ZONE_G seq 210 permit 10.10.10.0/24

ip prefix-list ZONE_G seq 310 permit 10.10.203.0/24
ip prefix-list ZONE_G seq 320 permit 10.10.204.0/24
route-map AS-500-Link1-OUTGOING permit 30
match ip address prefix-list ZONE_G
set community 500:80

4.4) Zone_B and rest of ISP-A’s IP blocks: ISP-D-Link1 Ebgp neighbor as 3rd link, with local-pref 70:

ip as-path access-list 2 permit ^$
route-map AS-500-Link1-OUTGOING permit 40
match as-path 2
set community 500:70
Note: “match as-path 2” instruction includes also the networks block 10.10.192.0/20 and 10.10.224.0/19 for the redundancy aggregation purposes.

As a result:
RT-A#sh ip bgp neighbors 40.40.40.1 advertised-routes
BGP table version is 107225231, local router ID is 10.10.193.62
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale, m multipath, b backup-path, x best-external
Origin codes: i – IGP, e – EGP, ? – incomplete
Network Next Hop Metric LocPrf Weight Path
*> 11.11.224.0/24 11.11.224.3 0 32768 i
*> 11.11.224.0/19 0.0.0.0 0 32768 i
*> 11.11.229.0/24 11.11.226.230 0 32768 i
r>i11.11.230.0/24 11.11.226.27 0 90 0 i
r>i11.11.232.0/24 11.11.226.27 0 90 0 i
r>i11.11.233.0/24 11.11.226.27 0 90 0 i

r>i11.11.248.0/24 11.11.226.27 0 90 0 i
r>i11.11.249.0/24 11.11.226.27 0 90 0 i
r>i11.11.250.0/24 11.11.226.27 0 90 0 i
r>i11.11.251.0/24 11.11.226.27 0 90 0 i
r>i11.11.252.0/24 11.11.226.27 0 90 0 i
r>i11.11.253.0/24 11.11.226.27 0 90 0 i
r>i11.11.254.0/24 11.11.226.27 0 90 0 i
r>i11.11.255.0/24 11.11.226.27 0 90 0 i
r>i10.10.192.0 11.11.224.3 0 90 0 i
*> 10.10.192.0/20 0.0.0.0 0 32768 i
r>i10.10.193.0 11.11.224.3 0 90 0 i
r>i10.10.194.0 11.11.224.3 0 90 0 i

r>i10.10.203.0 11.11.224.3 0 90 0 i
r>i10.10.204.0 11.11.224.3 0 90 0 i
*> 10.10.205.0 0.0.0.0 0 32768 i
*> 10.10.206.0 0.0.0.0 0 32768 i
*> 10.10.207.0 11.11.230.254 0 32768 i
*> 50.50.64.0 11.11.225.2 0 2000 i
*> 50.50.64.0/18 11.11.225.2 0 2000 i


Total number of prefixes 46

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