[j-nsp] Weird routing issue on my MX80

[Jeff Wheeler]

On Fri, Mar 29, 2013 at 9:37 AM, Matthew Crocker <matthew at corp.crocker.com>
wrote:
> Is it possible for the FIB to contain different information than what's
in 'show route'?
> How do I look at whats in the FIB?

Yes, it is possible.  Start with user at cli> *show pfe route ip prefix
192.0.2.0/24*

> How do I reset the FIB and resync it with the actual routes?

If only Junos would get a command-line tree like *clear cef* so the user
has a reasonable option (not rebooting PFEs) for fixing these problems.
 But that would first require Juniper to admit that this happens often
enough that customers need it.  It took Cisco a few years to reach that
point with customers begging for things like CEF Scanner.

I do not think this is your problem though.  If you ran show route A.B.C.0
detail on the ASBR that is connected to your customer, you must either be
doing ECMP to a customer loopback IP, some other ebgp-multihop business, or
whatever.  In any case, you didn't provide enough relevant information for
anyone to say for certain; but I suspect your router is not malfunctioning.
 You have probably just made a mistake.

> show route A.B.C.0 detail
>
> inet.0: 439841 destinations, 876907 routes (439825 active, 0 holddown, 32
hidden)
> Restart Complete
> A.B.C.0/24 (1 entry, 1 announced)
>         *BGP    Preference: 170/-101
>                 *Next hop type: Indirect*
>                 Address: 0xdeadbeef
>                 Next-hop reference count: 6
>                 Source: X.Y.Z.11
>                 Next hop type: Router, Next hop index: 1048574
>                 Next hop: Q.W.E.195 via ge-1/1/1.0
>                 Next hop: X.Y.Z.11 via ge-1/1/2.0, selected
>                 Protocol next hop: *T.U.V.122*
>                 Indirect next hop: 160865a0 1048575
>                 State: <Active Int Ext>
>                 Local AS:  1111 Peer AS:  1111
>                 Age: 13:39      Metric: 0       Metric2: 20
>                 Task: BGP_1111.X.Y.Z.11+12834
>                 Announcement bits (3): 0-KRT 4-BGP RT Background
5-Resolve tree 1
>                 AS path: 22222 I
>                 Accepted
>                 Localpref: 100
>                 Router ID: M.N.O.169

If this were a vanilla eBGP session to the customer and your paste is from
the ASBR terminating the customer's session / circuit, it would say *Next
hop type: Router* so you might want to double-check the differences between
the "correct" and "incorrect" customer routes before investigating further.

If you do find the PFE route doesn't match the software's idea of what
should be in the FIB, I will be a bit surprised in this case; but I think
the above should be helpful either way.
-- 
Jeff S Wheeler <jsw at inconcepts.biz>
Sr Network Operator  /  Innovative Network Concepts