[j-nsp] Re: M10 maximum throughput

Daniel Roesen dr at cluenet.de
Sat Dec 31 10:26:58 EST 2005

On Sat, Dec 31, 2005 at 01:00:30PM -0200, Rubens Kuhl Jr. wrote:
> A good description of the process is found at
> http://juniper.cluepon.net/index.php/J-cell
> But I disagree with the wiki text on
> http://juniper.cluepon.net/index.php/FPC_Bandwidth that states 3.2
> Gbps as a realistic worst case, because not all packets will have
> sizes that are multiple of 64 bytes, which is the only case that would
> achieve the 3.2 Gbps maximum.
> This reference (http://www.nlanr.net/NA/Learn/Gm/pktsizes.html) states
> that 40 byte packets account for 40% of the packets flowing around; 40
> byte packets require 16 byte paddings for each J-Cell, so if all other
> packets would be 64 byte multiples, performance would already been
> limited to 2.72 Gbps.

Indeed. With some simple math (and knowing the architecture in detail)
you can easily come up with the worst case IP packet size (and other
properties) to stress the router the most. :-)

Best regards,

CLUE-RIPE -- Jabber: dr at cluenet.de -- dr at IRCnet -- PGP: 0xA85C8AA0

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