Subject: Re: Last Call: 'Maximum Transmission Unit Signalling Extensions for the Label Distribution Protocol' to Proposed Standard

From: "Adrian Farrel" <[email-masked]>
Date: Mon, 3 Nov 2003 00:12:54 -0000

Hi,

2.4. MTU TLV

   The MTU TLV encodes information on the maximum transmission unit for
   an LSP, from the advertising LSR to the egress(es) over all valid
   paths.

   The encoding for the MTU TLV is:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|1|      MTU TLV (0x0XXX)     |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              MTU              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   MTU

   This is a 16-bit unsigned integer that represents the MTU in octets
   for an LSP or segment of an LSP.

Is this unnecessarily limiting? Shouldn't we support MPLS over L2 technologies that support larger than 64k MTUs?

Cheers,
Adrian

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From: Kireeti Kompella <[email-masked]>
Date: Tue, 4 Nov 2003 12:09:33 -0800 (PST)

Hi Adrian,

> Is this unnecessarily limiting? Shouldn't we support MPLS over L2 technologies that support larger than 64k MTUs?

I'm happy to do so, but I'm not aware of any L2 technology that
supports MTUs greater than 64K.  But if no one objects, this field can
be made 32 bits, assuming that that's big enough :-)

Kireeti.
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From: Alex Zinin <[email-masked]>
Date: Tue, 4 Nov 2003 13:39:43 -0800

Kireeti,

  What about existing implementations?

-- 
Alex
http://www.psg.com/~zinin/

>> Is this unnecessarily limiting? Shouldn't we support MPLS over
>> L2 technologies that support larger than 64k MTUs?

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From: Kireeti Kompella <[email-masked]>
Date: Thu, 6 Nov 2003 20:39:53 -0800 (PST)

>   What about existing implementations?

There are none that I know of.  If there are any, I would urge them to
speak up!

Kireeti.
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