netdev - RE: [PATCHv2 net-next 0/4] Small fix for TCP PMTU

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CAEEABA@AcuExch.aculab.com>
Date:	Thu, 26 Feb 2015 13:40:32 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Fan Du' <fan.du@...el.com>,
	"johnwheffner@...il.com" <johnwheffner@...il.com>
CC:	"edumazet@...gle.com" <edumazet@...gle.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"fengyuleidian0615@...il.com" <fengyuleidian0615@...il.com>
Subject: RE: [PATCHv2 net-next 0/4] Small fix for TCP PMTU

From: Fan Du
> This patchset performs some small fix and enhancement
> for current TCP PMTU as per RFC4821 with below changes:
> 
> Patch1/4: Set probe mss base to 1024 Bytes per RFC4821
> Patch2/4: Do not double probe_size for each probing,
>           use a simple binary search to gain maximum performance.
> Patch3/4: When it comes to blackhole detection, shrink current
> 	  mss for next probing.
> Patch4/4: Create a probe timer to detect enlarged path MTU.

Isn't the most likely problem PPPoE blackholes?
Where a reduction of the PMTU from 1500 to (IIRC) 1492 is
all that is required?

Would seem appropriate to test that value reasonable quickly.

	David

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