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From: Roland Dreier <rdreier@cisco.com>
To: Rick Jones <rick.jones2@hp.com>
Cc: "Zou\, Yi" <yi.zou@intel.com>,
	"netdev\@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-scsi\@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"Leech\, Christopher" <christopher.leech@intel.com>, "Dev\,
	Vasu" <vasu.dev@intel.com>, "Love\,
	Robert W" <robert.w.love@intel.com>, "Ma\,
	Steve" <steve.ma@intel.com>, "Waskiewicz Jr\,
	Peter P" <peter.p.waskiewicz.jr@intel.com>, "Kirsher\,
	Jeffrey T" <jeffrey.t.kirsher@intel.com>
Subject: Re: Question regarding protocol specific mtu for FCoE
Date: Wed, 03 Jun 2009 14:21:11 -0700	[thread overview]
Message-ID: <adazlcp814o.fsf@cisco.com> (raw)
In-Reply-To: <4A26E4AE.4020607@hp.com> (Rick Jones's message of "Wed, 03 Jun 2009 14:01:34 -0700")

 > So FCoE cannot say "fcoe_mtu = min(OPTIMAL_FCOEMTU,netdev->mtu)" and
 > send-down frames based on that?

I think the point is that FCoE wants to use OPTIMAL_FCOEMTU (2KB + a bit
for headers) even when netdev->mtu is 1500.  (eg datacenter network
supports baby jumbo frames so FCoE traffic that stays within the network
should use OPTIMAL_FCOEMTU, while lots of IP traffic is going out onto a
1500-byte MTU campus and having TCP doing lots of PMTU discovery is a
pain)

 - R.

  parent reply	other threads:[~2009-06-03 21:21 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-03 17:56 Question regarding protocol specific mtu for FCoE Zou, Yi
2009-06-03 18:03 ` Rick Jones
2009-06-03 19:16   ` Zou, Yi
2009-06-03 19:27     ` Ben Hutchings
2009-06-03 20:43       ` Zou, Yi
2009-06-03 20:57         ` Ben Hutchings
2009-06-03 22:22           ` Zou, Yi
2009-06-03 21:01     ` Rick Jones
2009-06-03 21:17       ` Waskiewicz Jr, Peter P
2009-06-03 21:21       ` Roland Dreier [this message]
2009-06-03 22:25         ` Zou, Yi
2009-06-03 22:36         ` Rick Jones
2009-06-03 23:00           ` Zou, Yi
2009-06-03 23:27           ` Roland Dreier

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