Information Technology Reference
In-Depth Information
Figure 11-22 shows an RPF check that fails.
Figure 11-22
Failed eBGP-Based MSDP SA RPF
Source
ISP 3
ISP 2
R1
R2
BGP Peer
MSDP Peer
I
S
P 4
ISP 5
SA Message
R3
R4
ISP 1
R5
R4 sends the SA to R5 in AS 1 and to R3 in AS 5. R3 in AS 5 accepts the SA and advertises
it to R5 in AS 1. The debug shown in Example 11-14 shows that this SA fails the RPF
check. The reason is that the first AS in the AS_PATH to the originating RP is AS 4. The
relevant BGP path information is shown in Example 11-13. The MSDP peer on which
the SA was received matches an e(m)BGP peer with AS 5, failing the RPF check.
Example 11-14
MSDP Debug for a Failed SA RPF Check
*Mar 3 09:57:57.499: MSDP(0): 10.3.1.5: Received 20-byte msg 99 from peer
*Mar 3 09:57:57.499: MSDP(0): 10.3.1.5: SA TLV, len: 20, ec: 1, RP: 10.1.0.1
*Mar 3 09:57:57.499: MSDP(0): 10.3.1.5: Peer RPF check failed for 10.1.0.1,
EMBGP route/peer in AS 4/5
