[c-nsp] Quick routing question.

[Matlock, Kenneth L]

Are you specifying the source IP address to be the .14 on your side?

Possibly the router is choosing another interface IP as the source
instead of .14

Ken Matlock
Network Analyst
Exempla Healthcare
(303) 467-4671
matlockk at exempla.org


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Drew Weaver
Sent: Thursday, September 09, 2010 11:10 AM
To: 'Jon Lewis'
Cc: cisco-nsp
Subject: Re: [c-nsp] Quick routing question.

Hi,


I assume the new connection doesn't have BGP turned up yet?
--
Correct, I am just trying to get it to where I can ping it first (which
is what I usually do, anyway).


Ah...but when you do this, are you sure x.x.x.13 is really the other
side 
of your 10G connection?  This is ethernet, so when you try to ping 
x.x.x.13 from your router, it sees a route for x.x.x.12/30 via the 10G 
Level3 interface, and sends an arp request for x.x.x.13.  If Level3's
end isn't 
actually configured for the /30 you are, they're not going to reply to 
that arp...and maybe the x.x.x.13 you're looking for really is in use 
somewhere else on their network?  
--
All valid points, when I trace route to .13 from the host that can ping
it I see:

[root at vmz bin]# tracert x.x.x.13
traceroute to x.x.x.13 (x.x.x.13), 30 hops max, 40 byte packets
 1  gw (gw)  0.486 ms  0.458 ms  0.463 ms
 2  core (core)  0.460 ms  0.710 ms  0.709 ms
 3  rtr (rtr)  0.427 ms  0.428 ms  0.425 ms
 4  x.x.x.Level3.net (x.x.x.13)  3.238 ms  3.238 ms  3.236 ms

However, I can't know whether the return traffic is coming back in on
that connection, or not.

Are you redistributing x.x.x.12/30 into 
your IGP, or might those packets be going out the old connection?
--
Yes, and see above.

What's show ip arp on your router show you?
--
rtr#sh ip arp
Protocol  Address          Age (min)  Hardware Addr   Type
Interface
Internet  x.x.x.14              -   xxxx.xxxx.a9dc  ARPA
GigabitEthernet2/1/0
Internet  x.x.x.13             14   xxxx.xxxx.4d7a  ARPA
GigabitEthernet2/1/0
Internet  x.x.x.12              -   xxxx.xxxx.a9dc  ARPA
GigabitEthernet2/1/0

(Ignore the 'gigabit' part, on 12000s for some reason they never changed
the interface names).

thanks,
-Drew


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