bypass routing table for testing purposes

m4rtin · November 2012

I receive 10.10.10.0/20 prefix from 192.168.1.1 via BGP:

root@M10i> show route 10.10.10.161 protocol bgp next-hop 192.168.1.1 table inet.0

inet.0: 437590 destinations, 1439597 routes (430210 active, 14 holddown, 20622 hidden)
+ = Active Route, - = Last Active, * = Both

10.10.10.0/20       [BGP/170] 04:12:00, MED 0, localpref 120
                      AS path: 65401 65402 65403 65404 I
                    > to 192.168.1.1 via ge-0/1/0.0

root@M10i> traceroute 10.10.10.161 gateway 192.168.1.1 no-resolve    
traceroute to 10.10.10.161 (10.10.10.161), 30 hops max, 48 byte packets
 1  192.168.1.1  0.360 ms !S  0.316 ms !S  0.336 ms !S

root@M10i> traceroute 10.10.10.161 gateway 192.168.1.1 no-resolve bypass-routing 
traceroute to 10.10.10.161 (10.10.10.161), 30 hops max, 48 byte packets
 1  192.168.1.1  0.336 ms !S  0.338 ms !S  0.365 ms !S

root@M10i>

As you can see, it's not active route(no + or * in front of it). However, I would like to route packets over this 192.168.1.1 next-hop address for testing purposes without changing the configuration(for example increasing the local preference). For some reason I receive "192.168.1.1 0.360 ms !S 0.316 ms !S 0.336 ms !S" from next-hop router. Any ideas why? Or is such testing possible on JUNOS?

zoidberg · November 2012

It looks like you are bypassing the routing table just fine. The packets reach the 192.168.1.1 next-hop as you intended. However, 192.168.1.1 is telling you that it doesn't like the source-route option being used by your traceroute. Those options are often blocked on networks.

Instead of specifying the gateway, can you try doing traceroute 10.10.10.161 bypass-routing interface ge-0/1/0.0 and see if that works for you? If you drop the gateway out of the traceroute, I don't think it will use the source-route option in the packet.

bypass routing table for testing purposes

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