nanog mailing list archives
Re: TCP and WAN issue
From: Leo Bicknell <bicknell () ufp org>
Date: Tue, 27 Mar 2007 20:44:05 -0500
In a message written on Tue, Mar 27, 2007 at 02:41:13PM -0700, Philip Lavine wrote:
This is the exact issue. I can only get between 5-7 Mbps. So the question is really what incremental performance gain do WAN accelerators/optimizers offer? Can registry/OS tweaks really make a significant difference because so far with all the "speed enhancements" I have deployed to the registry based on the some of the aforementioned sites I have seen no improvement.
In short, yes. Working for an ISP with colos on both coasts I helped customers on numerous occasions "tune" their operating system. A plain jane desktop from choose your favorite vendor today will do ~300-~500Mbps/sec of FTP with only minor tuning assuming you have good disks (e.g. not a laptop). Most servers can be easily tuned to chew a full gigabit. TCP Window Scale, Selective Acknowledgement, and a "TCP Send" and "TCP Receive" buffers that are big enough to handle your bandwidth*delay product (*2 for a good margin) are all that's required. Jumbo frames are not, and in fact make little difference. All of the TCP limits are 100% the same with Jumbo frames, and most NIC's generate roughly the same number of Interrupts with Jumbo frames enabled. You're saving a little bit of IP processing overhead on the end hosts, but I doubt you'll measure it. Wan optimizers are extremely complex points of failure that generally mess with the protocol in ways that are extremely dangerous, they should only be used if you don't have direct access to the end boxes to fix them. Google can turn up 50 write ups on how to tune your settings better than I could ever write here. -- Leo Bicknell - bicknell () ufp org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/ Read TMBG List - tmbg-list-request () tmbg org, www.tmbg.org
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Current thread:
- Re: TCP and WAN issue, (continued)
- Re: TCP and WAN issue Steve Meuse (Mar 27)
- Re: TCP and WAN issue Marshall Eubanks (Mar 27)
- Re: TCP and WAN issue Andre Oppermann (Mar 28)
- Re: TCP and WAN issue Marshall Eubanks (Mar 28)
- Re: TCP and WAN issue Simon Leinen (Mar 28)
- Re: TCP and WAN issue Andre Oppermann (Mar 28)
- Re: TCP and WAN issue Philip Lavine (Mar 27)
- Re: TCP and WAN issue Roland Dobbins (Mar 27)
- RE: TCP and WAN issue michael.dillon (Mar 27)
- Re: TCP and WAN issue Roland Dobbins (Mar 27)
- Re: TCP and WAN issue Roland Dobbins (Mar 27)
- Re: TCP and WAN issue Adrian Chadd (Mar 27)
- Re: TCP and WAN issue Leo Bicknell (Mar 27)
- Re: TCP and WAN issue Eric A. Hall (Mar 27)
- Re: TCP and WAN issue Philip Lavine (Mar 27)
- Re: TCP and WAN issue Joe Maimon (Mar 27)
- Re: TCP and WAN issue Robert Boyle (Mar 28)