[80098] in North American Network Operators' Group
Re: Slashdot: Providers Ignoring DNS TTL?
daemon@ATHENA.MIT.EDU (Robert M. Enger)
Sun Apr 24 16:41:22 2005
Date: Sun, 24 Apr 2005 16:40:50 -0400
To: sthaug@nethelp.no
From: "Robert M. Enger" <enger@comcast.net>
Cc: nanog@merit.edu
In-Reply-To: <95694.1114374180@bizet.nethelp.no>
Errors-To: owner-nanog@merit.edu
Steinar:
There is a large body of work from competent and well known
researchers that assert the claim. I certainly lack standing to question their results.
Empirically, download speeds to home are nearly cut in half (18Mbps) from sources
that are subjected to packet reordering along the path.
More to the point however, I note that Jay is the author of RFC2100.
I think he's just having a little bit of fun. My apologies for belaboring the performance issue.
Bob
At 04:23 PM 4/24/2005, sthaug@nethelp.no wrote:
>> In your note below you speak of 'moving on to something else' when
>> PPLB comes.
>>
>> PPLB destabilizes TCP. It elicits erroneous retransmissions,
>> squanders capacity and lowers performance.
>
>I would actually dispute this. I agree that PPLB will *occasionally*
>lead to out-of-order packets, which will lead to lower TCP performance
>*when it happens*. To many customers this is acceptable as long as PPLB
>gives them improved performance *most of the time*. And this is what we
>saw very clearly at my previous employer - PPLB worked very well, and
>gave clearly increased performance, *most of the time*.
>
>As mentioned in another message, I don't really believe PPLB is coming.
>Instead I believe PPLB is something which is probably being *less* used
>now than a few years ago, since other link bundling methods are more
>easily available now (than they were a few years ago) - and these link
>bundling methods occur at a layer below TCP, and are invisible to TCP
>(no packet reordering problems).
>
>Steinar Haug, Nethelp consulting, sthaug@nethelp.no
