[uanog] Re: [nsp] Rate - limiting

On Sat, May 22, 2004 at 12:07:09PM +0300, Volodymyr Yakovenko wrote:

Hello!

Коллеги, у когото в продакшине подобная связка (random-detect + rate-limit) используется?

Ежели да, то на каком железе/IOS-е и как впечатления сравнительно с shape-ом?

У меня было на 6500/12.1(19)E. Лучше, чем просто rate-limit, хуже, чем shape.

----- Forwarded message from Bruce Robertson -----

X-Mailer: exmh version 2.6.3 04/04/2003 with nmh-1.0.4 To: Mikael Abrahamsson Subject: Re: [nsp] Rate - limiting Date: Thu, 20 May 2004 14:29:07 -0700 From: Bruce Robertson Cc: cisco-nsp@puck.nether.net

...

Rate limiting at lower speeds severelt impacts TCP performance, a single TCP session hitting a rate limit will start, hit the ratelimit, lose several packets, pretty much go into slow-start, go logarithmically up again to the rate limit, hit the hard ceiling and then go into slow-start again, cutting the used bandwidth to approx 40% of the ratelimit.

This behavior is avoided if you use random-detect along with rate limiting. Here's an example that works perfectly at limiting a user to 500 Kb/s:

interface FastEthernet0/0 no ip address random-detect

interface FastEthernet0/0.22 encapsulation isl 22 ip address x.x.x.x y.y.y.y ip verify unicast reverse-path no ip redirects no ip proxy-arp rate-limit input 496000 93750 187500 conform-action transmit exceed-action drop rate-limit output 496000 93750 187500 conform-action transmit exceed-action drop

-- Bruce Robertson, President/CEO +1-775-348-7299 Great Basin Internet Services, Inc. fax: +1-775-348-9412 http://www.greatbasin.net

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----- End forwarded message -----

-- Regards, Volodymyr.

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