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VOIP & SCN over xDSL

VOIP & SCN over xDSL

VOIP & SCN over xDSL


We are encountering some really strange occurences.  Running a SOHO at one site and 403 at the other.  Both with VCM modules and running 2.0 software.  They both have Xdsl and firewalls configured with an IPSEC tunnel to each other.  A new "VPN" or "VOIP" line has been created at both sites and VOIP worked superbly for 7 days!  (by the way they have static IP Addresses - so not a DHCP lease runnning out).  After 7 days the link drops and will not re-establish.  When we use the monitor program and monitor the AVRIPS at tboth ends we find the following:

The SOHO sends and recieves, the 403 only sends and does not recieve.  we have deleted and started again - this worked 7 days ago but when it occured again today we can not get the link back up?, the only thing we have left to do is to blat it and start again or put in a new 403.  the tunnel works fine throughout and Terminal Services runs great across it.....

Any one got any ideas or pointers?

Thanks guys

RE: VOIP & SCN over xDSL

What your saying is that rebooting the Ip Offices will cause it to work for another 7 days? If you have to default it to get it too work then that is a problem.
If that is the cause I have a personal program to reboot automatically if you want it. We get hang ups on links between systems and use my program to reboot on a scheduled basis to avoid problem, until avaya someyear -oopss... I mean day fixes it.

RE: VOIP & SCN over xDSL

I would think that the fault with your VPN connections dropping off or not passing traffic until the router is reset lies with the MTU setting on the routers being too large.

I have this issue at many sites and lowering the MTU resolved this issue.

Please see below email from Dlink regarding a case I had logged regarding a site with IP Sec over ADSL. This site was using 2 X Dlink 804V's I would think you are using a different firwall device but the technology and concept is the same.

Please make sure with your setting under VPN Settings... for "Key Life" and also
"IKE Life Time" are the same for both side of the VPN.

Also please try to set the MTU to 1400 or 572 to see if this will stable your
connection between the two 804V.
This can be done under Advance Setting --> System Parameters on the DLINK 804v's.

If IPL's ADSL tails are running PPPoE I would suggest a MTU of 1492, if not try 1400, Most likely try 1430 The size VPN IP Sec and PPTP prefers. I would not be changing the MTU on PC's, only the Netgear routers.

I also looked on the Netgear web site and found the following
1500. The largest Ethernet packet size; it is also the default value. This is the typical setting for non-PPPoE, non-VPN connections. The default value for NETGEAR routers, adapters and switches.
1492. The size PPPoE prefers.
1472. Maximum size to use for pinging. (Bigger packets are fragmented.)
1468. The size DHCP prefers.
1460. Usable by AOL if you don't have large email attachments, etc.
1430. The size VPN and PPTP prefer.
1400. Maximum size for AOL DSL. 576. Typical value to connect to dial-up ISPs.
Worth a go :)

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