[SunRay-Users] Gigabit Sun Ray switches revisited (stripes and hanging networkinterfaces)

Ivar Janmaat ijanmaat at xs4all.nl
Wed Oct 7 22:04:16 EEST 2009


I thought I just could replace my 100 Mbit switch with a gigabit switch.
Man was I wrong......

Setup:
Gigabit network interface on Server.
Sun Ray Server Software 4.2 ea 2
Solaris Nevada Build 123
Sitecom Network Gigabit Switch
Linksys SLM2008 Gigabit Switch
Linksys SRW2008 Gigabit Switch
Sun Ray 270

Stress test:
Open Eye of Gnome image viewer on the Sun Ray and click through about 30
high resolution images

Situation 1:
SR Server <-------> SR 270

This works perfect!

Situation 2:
SR Server  <----> Gigabit switch <-----> SR 270

There is packet loss. The build up of the images is  hampering and I see
stripes instead of blocks.
So what went wrong? I remembered the post in November 2007 in which Kent
explained this phenomenon:

"The traffic is sent in little bursts at 10 ms intervals. Since it's
briefly sent at 10x the rate that the output port can handle on the
switch, some buffering is required on the switch. Bad switches (or
switches configured to toss UDP packets easily) don't do this buffering
correctly."

So I arranged for the two more expensive Linksys switches. But all three
8 port switches (Sitecom and Linksys) gave the same results. Although
larger 24 port switches probably have enough memory to buffer, most 8
port switches apparently do not. As a result the user performance is
very bad.
Does anyone know about an 8 port Gigabit switch with enough buffer memory?
Should the buffer memory be at least the size of the Solaris server udp
buffer size or should it be bigger?

Workaround hangs server network interface!
As suggested in earlier e-mails to the list I reduced the server port on
the Linksys SLM2008 from auto-negotiate (1GB) to 100Mb fixed. This
resulted in less striping but to my surprise the servers network
interface died after clicking through about 20 pictures in Eye OG.  The
same thing happened when I tried it with the Linksys SRW2008 switch.
The only workable solution I found was on the SRW2008.
It is: Leave the port setting "auto-negotiate" on "enable" but change
the "admin advertisement" from "Max capability" to "100 Full" This will
remove all striping and it does not hang up the network interface on the
server.

My question: Is this bug (dead Gigabit server interface) for
Opensolaris or for SRSS 4.2?

As for ease of Sun Ray adoption world wide.....
There should be a better workaround than to reduce bandwidth.

Kind regards,

Ivar










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