[j-nsp] RFC2544 on Juniper MX960 10G ports

[Chris Evans]

Joerg,

The hardware we have in our lab is the 20xSFP + 2x10Gig.. JTAC says this
'should' work but obviously it doesn't.. I tested it on an EX switch and it
had no issues.. In a simple L2 mode the MX lost about 47% packets at 64byte
10Gig line rates. In L3 mode is lost about 5.2%.. This is when testing full
duplex flows. This was with 9.6R3.8.. There is a known PR related to this
issue.

Hope to have some resolution sometime this week..

On Sun, Mar 14, 2010 at 3:14 PM, Joerg Staedele <js at tnib.de> wrote:

> Hi,
>
> so this means that this Linecard is not able to do line-rate forwarding
> with small frame sizes? What about other cards (20xSFP+2x10G) .. I guess
> they use exactly the same PFE hardware? So they have this limitation aswell?
>
> I am really confused now because in every document you read that the DPCE's
> are able to do line-rate at any frame-size?
>
> Regards,
>  Joerg
>
> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net [mailto:
> juniper-nsp-bounces at puck.nether.net] On Behalf Of Jonathan Lassoff
> Sent: Sunday, March 14, 2010 6:55 PM
> To: Serge Vautour
> Cc: juniper-nsp
> Subject: Re: [j-nsp] RFC2544 on Juniper MX960 10G ports
>
> Excerpts from Serge Vautour's message of Thu Feb 18 16:28:44 -0800 2010:
> > Hello,
> >
> > We recently used a traffic generator to run RFC2544 tests against a
> Juniper MX960. The 1G ports work flawlessly. 0% packet loss at all frame
> sizes.
> >
> > The 10G ports  (4x10G "R" card) didn't do as well. They dropped up to 25%
> packets with certain small frames (ex: 70 byte frames). The packet loss goes
> away almost completely for frames larger than 100 bytes. Our SE tells us
> this is normal and is due to how the MX chops the frames up into 64 byte
> cells inside the PFE. The 4x10G cards have 4 separate PFEs (1 per 10G port)
> and each of them has 10G of bandwidth. 10G of small frames essentially
> creates more than 10G of traffic inside the PFE. That explanation may not be
> 100% correct but I think it paints the right picture.
> >
> > Now the questions. Is this a problem on production networks with real
> world traffic? What about on VPN networks with alot of small frames like
> VoIP? Has anyone seen this problem creep it's head in production?
>
> Isn't the minimum Ethernet frame size 64 bytes? I think Ethernet II /
> Ethernet 802.3 requires this.
>
> Wouldn't this make the problem moot if you're just running Ethernet?
>
> Might be a problem with small ATM cells?
>
> Cheers,
> jof
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