Date: Sat, 17 Jul 1999 18:41:08 -0400 (EDT) From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: nagao@iij.ad.jp (NAGAO Tadaaki), des@flood.ping.uio.no, net@FreeBSD.ORG Subject: Re: dummynet -> rate limiting Message-ID: <199907172241.SAA24085@khavrinen.lcs.mit.edu> In-Reply-To: <199907171713.TAA16969@labinfo.iet.unipi.it> References: <19990718034115X.nagao@iij.ad.jp> <199907171713.TAA16969@labinfo.iet.unipi.it>
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<<On Sat, 17 Jul 1999 19:13:29 +0200 (MET DST), Luigi Rizzo <luigi@labinfo.iet.unipi.it> said: > Ok, i have no objections in principle, but i fail to see the use of > pps limiting. What does it model in a context (IP) where packets for sure > are not constant size ? Surely I shouldn't need to give this lesson to you, in particular, Luigi. As we all know, performance of network elements can be broken down into two components: per-packet cost, and per-bit (mostly serialization) cost. It may be necessary to protect a part of the network with high per-packet costs from an attacker intent on denying service from that network or device -- think ping floods. My network used to go down like clockwork every time some Linux machine got cracked, because the switches we had melted down under the load of processing 20,000 64-byte packets per second. (We have since managed to replace the losing hardware, but keep in mind that this is not an option open to everyone.) Cisco added a packet-rate-limiting feature in their ISP train some time ago, and it made it into 12.0 on certain platforms, so at least one big Cisco customer must think it's useful. -GAWollman -- Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same wollman@lcs.mit.edu | O Siem / The fires of freedom Opinions not those of| Dance in the burning flame MIT, LCS, CRS, or NSA| - Susan Aglukark and Chad Irschick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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