BGP Conditional Commercial
Using BGP conditional Route commercial is generally seen on the multi-homed environments i.e. websites having a connection to 2 totally different ISPs.
BGP Promote-map & Non-Exist Map
BGP will promote all of the routes to its neighbours if no filtering has been accomplished. BGP conditional commercial characteristic makes use of BGP advertise-maps and non-exist-maps to regulate the route ads.
If a route prefix will not be current within the output of the non-exist-map command, then the route specified by the advertise-map command is introduced. This characteristic is beneficial for multi-homed networks, through which some prefixes are marketed to one of many suppliers provided that data from the opposite supplier will not be current. This may assist us determine partial reachability.
We’ll take the assistance of the under instance to additional perceive the behaviour:
With the BGP conditional commercial characteristic, now you can accomplish these duties on R2:
- If 1.1.1.1/32 exists in R2’s BGP desk, then don’t promote the two.2.2.2/32 community to R3.
- If 1.1.1.1/32 doesn’t exist in R2’s BGP desk, then promote the two.2.2.2/32 community to R3.
CONFIGURATION ON R1:
community 1.1.1.1 masks 255.255.255.255
neighbor 9.9.12.2 remote-as 200
Associated- BGP Desk-Map
CONFIGURATION ON R2:
community 2.2.2.2 masks 255.255.255.255
neighbor 9.9.12.1 remote-as 100
neighbor 9.9.23.3 remote-as 300
neighbor 9.9.23.3 advertise-map Promote non-exist-map Non-Exist
!
access-list 10 allow 2.2.2.2
access-list 20 allow 1.1.1.1
!
route-map Non-Exist allow 10
match ip handle 20
!
route-map Promote allow 10
match ip handle 10
CONFIGURATIONS ON R3:
neighbor 9.9.23.2 remote-as 200
Associated- BGP Suppress Map & Attribute Map
VERIFICATION:
We see route of 1.1.1.1 is put in in BGP desk of R2 and therefore route of two.2.2.2 isn’t marketed to R3.
R2#sh ip bgp
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 9.9.12.1 0 0 100 i
*> 2.2.2.2/32 0.0.0.0 0 32768 I
R2#sh ip bgp neighbors 9.9.23.3 advertised-routes
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 9.9.12.1 0 0 100 i
Whole variety of prefixes 1
R3#sh ip bgp
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 9.9.23.2 0 200 100 I >>>> Just one.1.1.1/32 is acquired and never 2.2.2.2
Now we’ll shut down Lo0 interface on R1 to cease the commercial of 1.1.1.1 to R2 and therefore will see 2.2.2.2 is acquired on R3 now from R2.
R1(config)#int lo0R1(config-if)#sh
R2’s BGP Desk:
Standing codes: s suppressed, d damped, h historical past, * legitimate, > finest, i – inside,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 2.2.2.2/32 0.0.0.0 0 32768 i >>>>> No 1.1.1.1/32 route within the BGP desk
R2#sh ip bgp neighbors 9.9.23.3 advertised-routes
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 2.2.2.2/32 0.0.0.0 0 32768 i
Whole variety of prefixes 1
We see now R3 will obtain the route of two.2.2.2 from R2.
R3#sh ip bgp
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V legitimate, I invalid, N Not discovered
Community Subsequent Hop Metric LocPrf Weight Path
*> 2.2.2.2/32 9.9.23.2 0 0 200 I
Associated- Commercial Management in BGP With Incorrect Route Map Title
