[96281] in North American Network Operators' Group
Re: from the academic side of the house
daemon@ATHENA.MIT.EDU (Simon Leinen)
Thu Apr 26 13:14:03 2007
From: Simon Leinen <simon@limmat.switch.ch>
To: Tony Li <tli@cisco.com>
Cc: "Steven M. Bellovin" <smb@cs.columbia.edu>,
Jim Shankland <nanog@shankland.org>, bmanning@karoshi.com,
nanog@merit.edu
In-Reply-To: <261AA204-EAC6-4FB9-9B65-9B08BD8B3EC4@cisco.com> (Tony Li's
message of "Wed, 25 Apr 2007 15:25:25 -0700")
Date: Thu, 26 Apr 2007 19:11:37 +0200
Errors-To: owner-nanog@merit.edu
Tony Li writes:
> On Apr 25, 2007, at 2:55 PM, Simon Leinen wrote:
>> Routing table lookups(*) are what's most relevant here, [...]
> Actually, what's most relevant here is the ability to get end-hosts
> to run at rate. Packet forwarding at line rate has been
> demonstrated for quite awhile now.
That's true (although Steve's question was about the routers).
The host bottleneck for raw 10Gb/s transfers used to be bus bandwidth.
The 10GE adapters in most older land-speed record entries used the
slower PCI-X, while this entry was done with PCI Express (x8) adapters.
Another host issue would be interrupts and CPU load for checksum, but
most modern 10GE (and also GigE!) adapters offload checksum
segmentation and reassembly, as well as checksum computation and
validation to the adapter if the OS/driver supports it.
The adapters used in this record (Chelsio S310E) contain a full TOE
(TCP Offload Engine) that can run the entire TCP state machine on the
adapter, although I'm more sure whether they made use of that.
Details on
http://data-reservoir.adm.s.u-tokyo.ac.jp/lsr-200612-02/
--
Simon.
