Re: [v6ops] Extension Headers / Impact on Security Devices

"Fred Baker (fred)" <fred@cisco.com> Fri, 29 May 2015 19:45 UTC

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From: "Fred Baker (fred)" <fred@cisco.com>
To: "Howard, Lee" <lee.howard@twcable.com>
Thread-Topic: [v6ops] Extension Headers / Impact on Security Devices
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Date: Fri, 29 May 2015 19:45:21 +0000
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References: <555AB8FA.2080405@si6networks.com> <F6AA9AEA-49F0-488C-84EA-50BE103987C8@nominum.com> <555B8622.5000806@isi.edu> <555BA184.8080701@gmail.com> <555BA43F.8010303@isi.edu> <5564FB74.5020303@gmail.com> <5564FE3F.4050102@isi.edu> <556503CF.4030101@gmail.com> <55650821.4060907@isi.edu> <55650E82.3090407@gmail.com> <20150527073943.GA54385@Space.Net> <D18CFF39.4C411%evyncke@cisco.com> <55675AEC.10602@isi.edu> <3EBA13CE-8E8A-4969-86B7-CD8047F876F1@cisco.com> <D18E2DCE.B385A%Lee.Howard@twcable.com>
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Cc: "Mark Townsley \(townsley\)" <townsley@cisco.com>, "v6ops@ietf.org" <v6ops@ietf.org>, "Stefano Previdi \(sprevidi\)" <sprevidi@cisco.com>
Subject: Re: [v6ops] Extension Headers / Impact on Security Devices
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> On May 29, 2015, at 11:54 AM, Howard, Lee <lee.howard@twcable.com> wrote:
> 
>> the networking industry already faced the mtu "issue" more than 15 years
>> ago with the introduction of the label stack. The reality of network
>> operators infrastructure is such that the mtu is not really an issue.
> 
> This statement surprised me so much I thought I should ask:
> "MTU is not really an issue" in general?

It's largely a question of equipment choice and configuration. Equipment made with merchant chips, and older equipment, may or may not support MTUs larger than 1500 bytes for an Ethernet frame, but the chips we use in our current products (I can't really speak for J or H, but AFAIK this is true of them as well) are quite content with a 9K MTU. If your source is sending 1500 byte frames, how large do you need the MTU to be?