[nsp] weird gre tunnel...--follow up

Haesu haesu at towardex.com
Sun Sep 28 12:42:54 EDT 2003


Thank you to all those who replied.
Most common questions to this issue looks like checking the TTL of the tunnel, and it
appears 12.0(25)S1 does allow ttl to be set on the interface.. Right now on both 
tunnels, ttl is set 255..

Do you guys think may be an upgrade to 12.0(26)S1 (I think that's the latest in 12.0S
train...) would solve this tunnel issue? I'll look at software center on Cisco web
site and see if I can find any related issues in regards to gre tunneling with the
current version I'm using.

Thanks!

-hc


On Sat, Sep 27, 2003 at 11:55:51PM -0400, Haesu wrote:
> An update on this issue:
> 
> Not only the immediate hop at the ends of GRE tunnel gets "skipped" on 12.0(25)S1, from time to time GRE tunnels randomly stop passing traffic. The workaround so far seems like deleting the tunnel and reconfiguring it to get the affected tunnel back online, which is kinda makeshift...
> 
> Any ideas/experiences/recommendations would be very appreciated. Thanks!!
> -hc
> 
> 
> On Sat, Sep 27, 2003 at 04:09:22PM -0400, Haesu wrote:
> > Hi,
> > 
> > I got a 7500 running IOS 12.0.25S1..
> > 
> > It has GRE tunnel with some routes pointed to it..
> > 
> > Before I installed IOS 12.0.25S1 (it had non-serviceprovider version before),
> > whenever I traceroute to certain destination going thru the GRE tunnel, the router
> > at the other end of the tunnel always shows up in traceroute, which is normal.
> > 
> > For example:
> > 1. my-7500-router
> > 2. remote-router-on-the-other-end-of-the-tunnel
> > 3. some-router
> > 4. destination-host
> > 
> > After I installed 12.0.25S1 on that 7500, now I am seeing somewhat weird problem..
> > The hop 2, which is the remote router on the other end of the GRE tunnel no longer
> > shows up in traceroute... It now looks like this:
> > 1. my-7500-router
> > 2. some-router
> > 3. destination-host
> > 
> > Any idea what is happening with the way GRE tunnels are behaving under 12.0.25S1?
> > Is this a bug with the version I have or is there a special setting I have to use?
> > The hop right after the tunnel being skipped in traceroute or other layer3 queries
> > quite bothers me..
> > 
> > Thanks,
> > -hc
> > 
> > -- 
> > Haesu C.
> > TowardEX Technologies, Inc.
> > Consulting, colocation, web hosting, network design and implementation
> > http://www.towardex.com | haesu at towardex.com
> > Cell: (978)394-2867     | Office: (978)263-3399 Ext. 174
> > Fax: (978)263-0033      | POC: HAESU-ARIN
> > _______________________________________________
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> 
> -- 
> Haesu C.
> TowardEX Technologies, Inc.
> Consulting, colocation, web hosting, network design and implementation
> http://www.towardex.com | haesu at towardex.com
> Cell: (978)394-2867     | Office: (978)263-3399 Ext. 174
> Fax: (978)263-0033      | POC: HAESU-ARIN
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/

-- 
Haesu C.
TowardEX Technologies, Inc.
Consulting, colocation, web hosting, network design and implementation
http://www.towardex.com | haesu at towardex.com
Cell: (978)394-2867     | Office: (978)263-3399 Ext. 174
Fax: (978)263-0033      | POC: HAESU-ARIN


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