nanog mailing list archives
Re: MTU of the Internet?
From: Frank Kastenholz <kasten () argon com>
Date: Mon, 09 Feb 1998 10:42:46 -0500
At 09:11 PM 2/7/98 -0800, Sean M. Doran wrote:
Tli was just pointing out n messages ago that no matter how well you do in terms of aggregating data traffic into bigger chunks, you still will see an enormous number of small packets around (ACKs). You have to be prepared to switch those at line rate; engineering for some statistical mix of big and small packets is asking for a disaster when someone suddenly goes simplex.
some of the histograms i've seen show close to 50% of the packets being 40 bytes long. the 'desired' tcp behavior is to have no more than 2 data packets for every ack (since congestion control uses ack-reception to pace the transmission of data and try to quickly detect losses).
There is, however, the spectre of there being so many SYNs flying around that they alone might cause congestion collapse. I dunno if I should be frightened of that or not
you should be. not because of the packet-load it causes (as tony pointed out, you have to be able to move 40-byte packets at 'fiber speed') but because it's a symptom of lots of short-lived tcp connections. these connections never get out of slowstart. when there is only a small number of them, it's not important. when there is a large number of them, you have large, non-congestion-controlled, data flows. it's called being nibbled to death by mice.
Current thread:
- Re: MTU of the Internet?, (continued)
- Message not available
- Re: MTU of the Internet? Jay R. Ashworth (Feb 08)
- Re: MTU of the Internet? Dean Gaudet (Feb 08)
- RE: MTU of the Internet? Joe Provo - Network Architect (Feb 06)
- Re: MTU of the Internet? Henry Linneweh (Feb 06)
- RE: MTU of the Internet? Peter Ford (Feb 06)
- Re: MTU of the Internet? Paul A Vixie (Feb 06)
- Re: MTU of the Internet? Sean M. Doran (Feb 07)
- Re: MTU of the Internet? Paul A Vixie (Feb 07)
- Re: MTU of the Internet? Sean M. Doran (Feb 08)
- Re: MTU of the Internet? Frank Kastenholz (Feb 09)
- Re: MTU of the Internet? Frank Kastenholz (Feb 09)
- Re: MTU of the Internet? Paul A Vixie (Feb 06)
- Re: MTU of the Internet? Phil Howard (Feb 07)
- Re: MTU of the Internet? Steven L. Johnson (Feb 09)
- Message not available
- Re: MTU of the Internet? Jay R. Ashworth (Feb 08)
- Re: MTU of the Internet? Sean M. Doran (Feb 08)
- Re: MTU of the Internet? John Hawkinson (Feb 08)
- Re: MTU of the Internet? Charles Sprickman (Feb 08)