set ip next-hop in 6509/MSFC 12.2(1)SXF10

[Jason Aarons]

Router A -----------------------------RouterB----------------------------RouterC

10.1.1.1/24                            10.1.1.2/24   10.2.2.1/24                               10.2.2.2/24

Set ip next-hop 10.2.22

On RouterA customer has set ip next hop with destination for ip address hanging off RouterC, I thought ip next-hop had to point to adjacent interface (eg set ip next-hop 10.1.1.2)?? They swear it was working before but I don’t see how. They thought so long as ip next-hop address is in routing table it should work.  What do you think?

-jason

[Jon Marshall]

jason.aarons@us.didata.com
Router A -----------------------------RouterB----------------------------RouterC
10.1.1.1/24                             10.1.1.2/24   10.2.2.1/24                               10.2.2.2/24
Set ip next-hop 10.2.22
On RouterA customer has set ip next hop with destination for ip address hanging off RouterC,  I thought ip next-hop had to point to adjacent interface (eg set ip next-hop 10.1.1.2)?? They swear it was working before but I don’t see how. They thought so long as ip next-hop address is in routing table it should work.  What do you think?
-jason

Jason

PBR can use a next-hop that is not a directly connected next-hop. It's called PBR recursive next-hop -

PBR recursive next-hop

Jon

[Jason Aarons]

But as-is in production they only have ip next-hop x.x.x.x which is not adjacent.  I understand that x.x.x.x must be adjacent, it can't be across a routed link.

Your suggesting as a fix changing to recursive to fix it?  They say it doesn't need fixing it worked before and want to know why it's broke. I think it shouldn't have worked to start with.

[Giuseppe Larosa]

Hello Jason,

I would look at RB.

if for some reasons RB has changed its route entry for the destination network may be pointing to RA you may have a routing loop (not exactly PBR works inbound on incoming interface not on the opposite direction)

Or the problem is in the CEF table of RA that has missed the correct resolution of the indirect next-hop

sh ip route 10.2.2.2

sh ip cef exact-route 10.2.2.2

or RA has now a better route to 10.2.2.2 going via another path.

I agree that this is not a good design, and I would use RB' ip address and eventually PBR on RB too if necessary pointing to RC.

Hope to help

Giuseppe