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8.3.1 using wrong lif for traceroutes

[ Edited ]

Seems like the 'net traceroute' command is broken in three ways:

 

1. Doesn't use the lif specified on the command line (i.e. -lif <lifname>)

2. Doesn't use the routing table to select the correct route - simply uses the default route in all cases.

3. Doesn't hit the destination I specified!!

 

Can anyone replicate this behavior?

 

fcnascl02::> net route show -vserver fcnascl02                                                               
  (network route show)
Vserver             Destination     Gateway         Metric
------------------- --------------- --------------- ------
fcnascl02
                    0.0.0.0/0         10.144.80.1     10
                    10.18.240.32/27   10.146.240.33   20
                    10.146.240.32/27  10.146.240.33   10  <--- Should be using this route because it is most specific


fcnascl02::> net int show -role intercluster -vserver fcnascl02
  (network interface show)
            Logical    Status     Network            Current       Current Is
Vserver     Interface  Admin/Oper Address/Mask       Node          Port    Home
----------- ---------- ---------- ------------------ ------------- ------- ----
fcnascl02
            fcnas04n0_snapmirror-n0-757
                         up/up    10.146.240.52/27   fcnas04n0     a0a-757 true  <--- lif specified in the command below
            fcnas04n1_snapmirror-n1-757
                         up/up    10.146.240.53/27   fcnas04n1     a0a-757 true


fcnascl02::> net traceroute -lif fcnas04n0_snapmirror-n0-757 -vserver fcnascl02 -destination 10.146.240.44  <-- same subnet
  (network traceroute)
traceroute to 10.146.240.44 (10.146.240.44) from 10.146.240.52, 64 hops max, 44 byte packets
 1  fcnas05n0-e0m (10.144.80.97)  0.300 ms  0.234 ms  0.177 ms  <--- WRONG destination lif shown - is it even using my destination?

 

 

fcnascl02::> net traceroute -node fcnas04n0 -vserver fcnascl02 -destination 10.146.240.44  <--- no lif selected, should use routing table
  (network traceroute)
traceroute to 10.146.240.44 (10.146.240.44), 64 hops max, 44 byte packets
 1  fcnas05n0-e0m (10.144.80.97)  0.371 ms  0.264 ms  0.232 ms  <--- WRONG destination lif shown again

 

 

 

This issue is impacting my ability to troubleshoot a cluster peer issue.

Re: 8.3.1 using wrong lif for traceroutes

Your desired path seems to have the same metric as that of the default route. Try decreasing that value using the "network route create -metric " commandline. System prefers the route which has the lowest metric. In case if there is a conflict, it may choose the route that comes first in the routing table.

Another possibility is the IP fastpath option. You can see whether it is enabled by using the following command.

 

For Data ONTAP 8.3.1 and later, run the following command:
::>options ip.fastpath.enable

 

IP fastpath is a feature that bypasses the routing table lookups thereby improving network performance. But it can cause issues in complex networks sometimes. One should be aware of the consequences of enabling or disabling this feature. If this is causing the issue, please log a case and get NetApp tech support involved. 

 

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