From: Bit Gossip (bit.gossip@chello.nl)
Date: Sun Aug 12 2007 - 08:02:39 ART
Group,
(As4 R4) --- (As1 R1) --- (ospf R3) --- (As1 R2) --- (As5 R5)
R4: originates 4.4.4.4 in BGP
R1: learn 4.4.4.4 from R4 via bgp and redistribute it in OSPF
router ospf 1
redistribute bgp 1 subnets route-map LUCA
!
router bgp 1
synchronization
table-map ALL
neighbor 14.0.0.4 remote-as 4
no auto-summary
!
ip as-path access-list 1 permit .*
!
access-list 1 permit 4.4.4.4
!
route-map LUCA permit 10
match ip address 1
!
route-map ALL permit 10
match as-path 1
set automatic-tag
!
R3: runs only OSPF and passes 4.4.4.4 on to R2
R2: redistribute OSPF into BGP
router bgp 1
synchronization
redistribute ospf 1 route-map O2B
neighbor 25.0.0.5 remote-as 5
no auto-summary
!
route-map O2B permit 10
match route-type external
set as-path tag
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This works great and on R2 I see 4.4.4.4 with correct AS-PATH and origin, but
note that in this case the AS-PATH is only one AS
R2#show ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 4.4.4.4/32 23.0.0.3 1 32768 4 i
But if I do some prepending on R4, the originator, the redistrubution on R2
OSPF -> BGP breaks and I don't see 4.4.4.4 in BGP anymore, while it is in
OSPF
Can we conclude that this feature can transport AS-PATH info accross OSPF only
when the AS-PATH contains a single AS?
This kind of make sense considering that the external tag field in the LSA
type 5 is only 32 bit long; I could not find this in the doc anyway.
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:10 ART