AT&T U-verse VDSL "fiber to the node" 24Mbit down / 3Mbit up
2Wire Router Model 3800HGV-B
Software Version

The 2Wire router appears to have a limit of 1024 TCP and UDP sessions. This limit appears to apply to all sessions regardless of any static IP, firewall off, DMZ plus, secondary router configurations.

I've tried using the 2Wire router alone and also configuring the 2Wire static IP addressing, firewall off, DMZ plus, etc. setup along with my own pfSense router/firewall. Either way it appears I exceed the 1024 session limit and sessions start being reset.

Running out of sessions isn't being caused by torrents or p2p etc. We're a business and our legitimate uses are exceeding this session limit.

AT&T tells me it's not possible to bridge the router or increase or avoid the session table limit.

I'm curious if anyone has found a way around either of these issues.

  • I'm not familiar with 2wire gear but is the fiber terminating directly into it or is it going through another piece of gear and you are just running ethernet into the 2wire? – Zypher Aug 13 '11 at 3:02
  • AT&T calls this service "Fiber to the node". The fiber terminates at a "node" a few blocks away and they run copper from the "node" a few blocks away to our office here. A copper phone line is connected to the back of the 2Wire. As far as my LAN is concerned I plug ethernet into the switchports on the back of the 2Wire. – caleban Aug 13 '11 at 3:28
  • Ah that sucks so i guess you can't just get a real router. Do they offer the option to get just a standard "modem" from them instead of a full on router? – Zypher Aug 13 '11 at 3:35
  • Not for the "Fiber to the node" service unfortunately. The speed and pricing for this service is very attractive but the 2Wire device is a deal breaker. AT&T told me the 2Wire 3800 was the only possible device and it's impossible to bridge. They said it had to do with the authentication among other things. I read elsewhere they're using 802.1x authentication. In order to use a normal bridge/modem instead I'd have to get different DSL service, the kind where they run copper from the CO to my office, not fiber to the node, and that's a lot slower connection. – caleban Aug 13 '11 at 3:57
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    @Zypher, UVerse is VDSL; they usually backhaul it via fiber, but it's not implicit. AT&T is the king of misrepresenting it's services of recent to make it sound like they're still competitive. – Chris S Aug 13 '11 at 4:14

I'm afraid your only real solution is a VPN. That will allow you to map all your TCP and UDP connections through what the modem/router will see as only a single session. You'll need to borrow/rent a machine on a real net connection somewhere to be the other end of your VPN and have that do your NAT.


There are a couple options. It isn't clear from the question about which connections are closing and if that is configurable. For instance do you have a bunch of web browsers and then also some ssh sessions, and you want to keep your ssh sessions open? You could setup a router internally that natted controlled sessions from the clients to the server. If you use a box that supports classification you could put limits on the number of sessions available to HTTP vs SSH traffic and timeout HTTP connections that are idle before closing SSH connections. You could probably also put a shorter timeout on HTTP connections to free up more space on the silly 2wire for longer running sessions.

Second option is routing through a box off your network. Maybe a VPS on linode.com or a server in a data center related to the business. You could setup an openvpn tunnel and then route traffic through it, the 2wire would only see one session for the openvpn tunnel.

I'd be curious how the pricing worked out for this vs Ethernet-over-Copper for the business side? Here in SF we can get EoC @ 10Mbps bidirectional for ~500/mo. It might be worth researching, unless it is significantly out of budget.

  • Regarding pricing in this area of Los Angeles: I have a $1,000/mo 10Mbit/s synchronous EOC scheduled to be installed in the future, it's taking a while, but I had to have something now and as far as I could tell AT&T and Time Warner were the only options. The AT&T connection we're using which will eventually be our backup is $95/mo. – caleban Aug 30 '11 at 20:54

I had a similar issue, in order to get some of my sessions back i changed the session TTL from 24 hours to 6 hours. this has freed up my sessions and I no longer run out.

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