linksys rv082 and voip 1

[akrauska]

Network is a small office lan behind a nortel contivity 1010...dsl modem out to home office where a second contivity 1010 is connected to a home pc. Problem is excessive fragmenting/packets when files are transferred from the office to the home via the tunnel...

a packet trace shows the same 12m file will transfer withing the lan with 40,000 packets, from the home to office pc via a tunnel, with 55,000 packets, but when the same file is transferred from the office via the tunnel to the home office pc, the packets jump to 145,000. Mtu is 1410, mss 1300 on both end vpn routers. Any ideas. I've spent two weeks working with nortel engineers with no success.

akrauska

 

[gacollier]

Have you tried running pings from both sides with variable size buffers using the don't fragment option? This should give you an idea of the MTU going both directions.

Example:

Endpoint A
ping xxx.xxx.xxx.xxx -l 1500 -f (where xxx.xxx.xxx.xxx is Endpoint B IP address).

Keep stepping down the "1500" figure until you no longer get an packet fragmentation error. That will give you your MTU from end point to end point. Next repeat the procedure from Endpoint B.

Let me know what you come up with.

 

[jono659]

I had to lower the MTU on my XP machines to 1350 before it became reliable. Handy little tool is Dr TCP

http://www.dslreports.com/drtcp

 

[akrauska]

Thanks for the feedback. Yes, I did a lot of ping tests to determine mtu size and yes, I use drtcp to change it. We ended up buying two off the shelf vpn routers (fvs318) configured them and the data transferred great....1200 size mtu packets on the trace vice 536.

Problem now is his ip phone doesn't work anymore.Nortel I2002 connected thru the tunnel to a bcm. Any ideas?

 

[gacollier]

ak,

What's the MTU on the router set at?