[c-nsp] Quick routing question.

Heath Jones hj1980 at gmail.com
Thu Sep 9 14:10:21 EDT 2010


I noticed that too Jon, I think its just a display thing - because it's
saying the interface name it also shows the mac..



On 9 September 2010 18:34, Jon Lewis <jlewis at lewis.org> wrote:

> On Thu, 9 Sep 2010, Drew Weaver wrote:
>
>  [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 <http://x.x.x.level3.net/> (x.x.x.13)  3.238 ms
>>  3.238 ms  3.236 ms
>>
>
> So you have redistributed the new connection /30 into your IGP.  With BGP
> not turned up, the return path is almost certainly not the reverse of the
> above...so is there some reason x.x.x.Level3.net<http://x.x.x.level3.net/>can't send packets back your way via the connected 10gigE?  I assume if you
> ask a Level3 engineer to ping you at x.x.x.14 from x.x.x.Level3.net<http://x.x.x.level3.net/>,
> it doesn't work?
>
>
> 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
>>
>
> That rules out my first guess.  Though probably not related, why is there
> an arp entry for .12?
>
>
> ----------------------------------------------------------------------
>  Jon Lewis, MCP :)           |  I route
>  Senior Network Engineer     |  therefore you are
>  Atlantic Net                |
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