what would cause incomplete arpa

Hi,
I was doing a lab last night and ran into an issue at middle and at the end.

The way I do things is once I am done with the basic switching I verify that
I have same subnet connectivity. Then again after I complete my
residrribution tasks I run tcl scripts on my routers and macro scripts on my
switches to verify connectivity to all the interfaces (the ones I am
involving in my routing through one form or another).
I do the samething with the macro's and tcl scripts at the end.

I also learned to run debug ip routing to look for pesky loops.

I ran into an issue where I could not ping a local interface after my
redistribution was complete. I was able to ping at the beginning of my lab.
This interface was one I have not added to any routing and that is
irrelevant to being able to ping it locally anyway. It was enabled and
up/up. I bounced it and same thing. Very odd. I checked everything and I
found nothing wrong.

So I rebooted the router in question and all my switches. After that I saw a
routing loop on my routers. But before I did not see it for some reason.
Another odd thing since I was running debug ip routing. II corrected the
loop and I was able to ping locally and to the remote router. The really odd
thing is that on the router I have two dot1q sub interfaces and through out
my ping problem I was able to ping it's neighbor. Both neighbors for the
dot1q sub interfaces sit on the same switch.

Which leads me to think this might have something to do with misconfiguring
something on my switches. They only two things I can think of at the moment
are that I messed up my MSTP (but I checked all instances and everything
looked fine on all my switches) and the other thing is that I configured one
to many port-channel load balancing on all my switches. The trunks are
fine.

At the end of my lab I ran into a similar situation where I could ping my
local interface but I could not ping my remote router out of one of the
dot1q interfaces. I can ping everything else in my whole network from
everywhere, debug ip routing shows routing is stable everywhere. Arp shows
an incomplete entry and when I run debug ip packet detail I see
encapsulation failed. Debug arp shows that the router is sending out an arp
request.

I was thinking maybe a spanning tree storm but I would see ping issues to my
other devices. I shut down all my routers and switches except 2 routers and
2 swithes that are related ( the direct path from router to router). I
changed the load balancing back to default and I ran out of time to continue
troubleshooting.

Any ideas?

-- 
-
"The more I learn the less I know". This is incredibly frustrating to me.
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