Hi,
I am confused about BGP selecting path.Here topology
R5 is in sub-AS 45.And advertise prefix 9.9.9.9/32.
R5#sh ip bgp
BGP table version is 14, local router ID is 5.5.5.5
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
*> 9.9.9.9/32 0.0.0.0 0 32768 i
*> 192.168.12.0 2.2.2.2 0 100 0 (23) i
* i 2.2.2.2 0 100 0 (23) i
R4 is in sub-AS 45 same R5 and it learn prefix 9.9.9.9/32 from R5.
R4#sh ip bg
BGP table version is 15, local router ID is 4.4.4.4
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
*>i9.9.9.9/32 5.5.5.5 0 100 0 i
* i192.168.12.0 2.2.2.2 0 100 0 (23) i
*> 2.2.2.2 0 100 0 (23) i
R4#sh ip bgp 9.9.9.9/32
BGP routing table entry for 9.9.9.9/32, version 10
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
2
Local
5.5.5.5 (metric 11) from 5.5.5.5 (5.5.5.5)
Origin IGP, metric 0, localpref 100, valid, confed-internal, best
R2 is in sub-AS 23 and it learn prefix 9.9.9.9/32 from R4.
R2#sh ip bgp
BGP table version is 4, local router ID is 2.2.2.2
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
*> 9.9.9.9/32 5.5.5.5 0 100 0 (45) i
*> 192.168.12.0 0.0.0.0 0 32768 i
R2#
R2#sh ip bgp 9.9.9.9/32
BGP routing table entry for 9.9.9.9/32, version 4
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
1 3
(45)
5.5.5.5 (metric 21) from 4.4.4.4 (4.4.4.4)
Origin IGP, metric 0, localpref 100, valid, confed-external, best
R3 is in sub-AS 23 and it learn prefix 9.9.9.9/32 from both R2 and R5.
R3#sh ip bgp
BGP table version is 3, local router ID is 3.3.3.3
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
* 9.9.9.9/32 5.5.5.5 0 100 0 (45) i
*>i 5.5.5.5 0 100 0 (45) i
*>i192.168.12.0 2.2.2.2 0 100 0 i
R3#
R3#
R3#sh ip bgp 9.9.9.9/32
BGP routing table entry for 9.9.9.9/32, version 2
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to update-groups:
2
(45)
5.5.5.5 (metric 11) from 5.5.5.5 (5.5.5.5)
Origin IGP, metric 0, localpref 100, valid, confed-external
(45)
5.5.5.5 (metric 11) from 2.2.2.2 (2.2.2.2)
Origin IGP, metric 0, localpref 100, valid, confed-internal, best
The question is, Why R3 select confed-internal(2.2.2.2) instead confed-external(5.5.5.5)?
Thank you in advance.