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.
WARNING: multiple messages have this Message-ID (diff)
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.
next prev parent reply other threads:[~2009-06-03 21:21 UTC|newest]
Thread overview: 17+ 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 21:21 ` Roland Dreier
2009-06-03 22:25 ` Zou, Yi
2009-06-03 22:36 ` Rick Jones
2009-06-03 22:36 ` Rick Jones
2009-06-03 23:00 ` Zou, Yi
2009-06-03 23:27 ` Roland Dreier
2009-06-03 23:27 ` Roland Dreier
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