[j-nsp] flow exports and next hops

Ben Buxton B.Buxton at Planettechnologies.nl
Tue Jun 10 12:27:53 EDT 2003

I'm trying to collect some stats using the flow exports feature of JunOS
but have come across a problem.

The router is setting the 'next-hop' value in the flow packet to
'' for
flows that are destined towards a nexthop at the other end of a
SONET link.

A 'show route' seems to give some clues as to the culprit:

> show route xxxx extensive 

inet.0: 122127 destinations, 212622 routes (122123 active, 3 holddown, 1
xxxx/32 (1 entry, 1 announced)
KRT in-kernel xxxx/32 -> {so-0/0/0.0}
        *OSPF   Preference: 10
                Next hop: via so-0/0/0.0, selected
                State: <Active Int>
                Local AS:  8737 
                Age: 6d 5:05:51         Metric: 4 
                Task: OSPF
                Announcement bits (3): 0-KRT 4-Resolve inet.0 5-RT 
                AS path: I

The next hop here only shows an interface rather than an IP address, so
this is why the flow packets have set for the next-hop.

Is there a way around this? My flow analysis software gets somewhat
and not happy when given a zero-value next hop, and ideally i'd like to
either the remote ip address of the SONET link or the 'final' next-hop.


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