[c-nsp] ip tcp adjust-mss <value> - Alternative?

chris at akko.id.au chris at akko.id.au
Sat Jul 2 00:38:54 EDT 2005


Thanks Arie,
That is something we've also looked at but it's not the silver bullet
that we are after for use with the 10K unfortunately.

The reason "ip tcp adjust-mss" has worked so well for us in the past
on our other smaller capacity boxes (7200/7301s acting as LNS') is
because it would cure the MTU issues for client machines (e.g. a LAN
of multiple workstation PCs) behinde older CPE/Gateway type devices
that don't handle fragmentation very well or at all, without the need
for manual adjustment of end-user MTU settings. 

Regards,
Chris

>
>---- Original Message ----
>From: arievayner at gmail.com
>To: ranmails at gmail.com
>Subject: Re: [c-nsp] ip tcp adjust-mss <value> - Alternative?
>Date: Fri, 1 Jul 2005 22:56:08 +0400
>
>>Another thing to look at (it's not perfect, but it's something) is
>>"Automatically Adjusting the IP MTU".
>>Look at this document on CCO:
>>
>>http://www.cisco.com/en/US/partner/tech/tk801/tk703/technologies_tec
>h_note09186a0080094c4f.shtml
>>
>>Arie
>>CCIE #12198
>>
>>On 7/1/05, Ran Liebermann <ranmails at gmail.com> wrote:
>>> Hi Chris,
>>> 
>>> I agree.
>>> Indeed this is a method I like the least (unsetting the DF bit),
>but
>>> some vendors, at least in the BRAS solutions, used to provide just
>>> this option.
>>> 
>>> In our network we make sure that all paths that a tunnel can go
>>> through will support MTU larger than 1500 bytes plus the tunnel
>header
>>> overhead.
>>> 
>>> (I just noticed that we replied eachother off-list, so I put it
>back
>>> on the list).
>>> 
>>> --
>>> Ran.
>>> 
>>> 
>>> On 29/06/05, [A] <chris at akko.id.au> wrote:
>>> > Hi Ran,
>>> > Thanks for your response. Apart from effectively disabling PMTUD
>itself,
>>> > what else if anything will clearing the df bit for only TCP
>packets break in
>>> > your experience?
>>> >
>>> > Obviously what we don't want is to cause more (or bigger)
>problems than we
>>> > actually fix by implementing something like this...
>>> >
>>> > Regards,
>>> > Chris
>>> >
>>> > ----- Original Message -----
>>> > From: "Ran Liebermann" <ranmails at gmail.com>
>>> > To: <chris at akko.id.au>
>>> > Sent: Wednesday, June 29, 2005 2:26 PM
>>> > Subject: Re: [c-nsp] ip tcp adjust-mss <value> - Alternative?
>>> >
>>> > Either trying harder to increase the MTU throughout the tunnel's
>path,
>>> > or using a route-map to unset the DF bit in packets that have it
>set
>>> > to 1.
>>> >
>>> > Regards,
>>> > --
>>> > Ran.
>>> >
>>> > On 28/06/05, chris at akko.id.au <chris at akko.id.au> wrote:
>>> > > Hi list,
>>> > > Just wondering what other SP's use as an alternative to the
>"ip tcp
>>> > > adjust-mss" command on platforms that don't support it (e.g.
>the
>>> > > 10008ESR
>>> > > PRE2) for working around MTU & fragmentation issues in an
>L2TP/PPPoE
>>> > > LNS
>>> > > environment.
>>> > >
>>> > > Thanks in advance.
>>> > >
>>> > > Regards,
>>> > > Chris
>>> > >
>>> > > _______________________________________________
>>> > > 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/
>>> > >
>>> >
>>> >
>>> 
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>>





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