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Chair

join:2002-04-08
San Francisco, CA

DSL Consistently disconnecting every 5 minutes.

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Disconnection
My DSL line consistently disconnects every 5 minutes for like a second, making streams stop and restart.

I have a rockstable connection otherwise, but the disconnects are annoying as I sometimes use VNC and it disconnects me constantly.

Is it possible to watch the connection and see if it's the connection that's dropping or is it my router?

My account is under itsalann


leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET
For regular ADSL (not Sonic Fusion with ADSL2+) there exist two competing but almost compatible standards:

ANSI T1.413 is the original standard for DSL in the US and initially used widely in North America. It has since then been replaced with the International ITU standard G.992.1 (also known as G.DMT). Most ADSL equipment supports both since the difference is minor.

A mismatch between DSL modem and DSLAM configuration on which of those two standards to use will result in frame alignment errors roughly every 5 minutes.

There may be an option in your DSL modem that you can change yourself (just select the opposite of what it is set currently).
--
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mythgard
Sonic.net

join:2006-01-18
Santa Rosa, CA
reply to Chair
I suggest you give us a call at 707-547-3400 or 1-888-766-4233, Monday - Friday from 6am - 11pm and Saturday and Sunday 8am - 10pm. You can check the current call volume and hold times before calling here: »www.sonic.net/contactus.shtml

There are some intermittent errors on the line that we can run some testing on to see if we can determine the location of the interference and get it resolved for you.
--
Tage J
Sonic.net Customer Support

Chair

join:2002-04-08
San Francisco, CA
reply to Chair
I called last night and no improvement; other than a 3Mbit drop in line speed.

It might be another issue if it doesn't work ( I'm on the phone currently ).

The drops are "shorter" is what my brother describes the drops.

I'd rather take the 5 minute disconnects if I lose so much speed though.

HuckWeed

join:2011-09-20

2 edits
Hi there,

I've actually had this problem on a few lines that I service for sonic.net, and it took a few months of steady complaints by my customers before I finally figured out that the firewalls in the routers sitting behind the sonic modem (running tomato or openwrt) were denying a dhcp query coming from sonic's dhcp server based on an IP mismatch, which was forcing the WAN connection to reset. It would take almost no time to re-establish the WAN, but the problem, as I'm sure you noticed, is that every connection you have (vnc, teamviewer, loading a streaming video, poorly coded applications that would crash etc.) would need to be re-established... a huge pain!

The solution is to poke a hole in the router firewall. I use IPTABLES and was able to issue/execute the following command:

iptables -I INPUT -p UDP -i vlan1 --dport 68 --sport 67 --source 110.139.165.56 -j ACCEPT

(The 110.139.165.56 ip is the ip address of the sonic dhcp server in both cases I saw... it's possible that you will have to change this value)

If you tell me which router you have exactly, I may be able to give you step by step instructions on how to view the logs (to pull the dhcp server IP) and to allow your router to include this IPTABLES entry automatically on startup.

I hope this helps! I spent at least 5 hours trying to figure out what the problem was before figuring this out!


DaneJasper
Sonic.Net
Premium,VIP
join:2001-08-20
Santa Rosa, CA
kudos:9
reply to Chair
Issues described as "Disconnection every five minutes" are generally due to firewalling by the customer of our DHCP packets. The initial DHCP lease is done via broadcast, and the lease interval is five minutes. Renewals are every five minutes, and are unicast. If you block those packets, your system will not have a lease, will lose it's IP, and will fall back to broadcast (which your firewall isn't blocking), then you get another initial five minute lease.

So - the fix is to check your firewall, and stop blocking traffic from our DHCP server!

-Dane


newsonicuser

@sonic.net
I'm having this same issue, how do I allow traffic from Sonic's DHCP server? I'm using the Netgear DG834.


newsonicuser

@sonic.net
I checked my firewall log for an IP that was getting blocked every 5 minutes. It was different from the one HuckWeed posted above (70.36.140.1 in my case) but configuring the firewall to allow it seems to have solved the disconnect problem. Is there a better way to do this? Will Sonic's DHCP server IP change often?

HuckWeed

join:2011-09-20
said by newsonicuser :

I checked my firewall log for an IP that was getting blocked every 5 minutes. It was different from the one HuckWeed posted above (70.36.140.1 in my case) but configuring the firewall to allow it seems to have solved the disconnect problem. Is there a better way to do this? Will Sonic's DHCP server IP change often?

I've not had the dhcp server IP change in 4-6 months.

What puzzles me is why sonic would utilize these rather draconian dhcp policies, especially on a dedicated dsl circuit. Why not have a 24hr lease time or in some way not have it be an issue in the first place?

My guess is that there are a small but significant amount of users who suffer from this problem with 'out of the box' configurations of many big box store consumer level routers, as well all the DIY people who use the various open source firmware like DDWRT, tomato, openwrt and the like. Some of these people live with the problem or just don't realize it and then there are those who simply get different service.

Dane, I love your company and all that you guys stand for, but I would like to hear (if you are able to tell us) the reasoning behind configuring your dhcp service like this?

Thanks!


DaneJasper
Sonic.Net
Premium,VIP
join:2001-08-20
Santa Rosa, CA
kudos:9
The short lease time assures that if there is a network outage or maintenance, that the average time a customer will be disconnected is just 2.5 minutes. A long lease can leave a customer "stranded", their system thinking they have a lease to an IP that we no longer route to them.

Looking at it another way, perhaps if you're losing connection every time the lease is to renew, it's better to detect and resolve that because it's more noticeable than it would be with a 60 minute or longer lease.

One item I'm curious about is if we can detect customers who are repeatedly failing to renew their lease due to their firewall settings, so that we could proactively communicate with them. We'll discuss this internally.

-Dane

Ravenheart

join:2006-02-10
Berkeley, CA

1 edit
reply to HuckWeed
Huckweed, I've had the disconnect problem but am trying your iptables command--thank you. I wonder how I verify the DHCP server address. I can't find it listed in my router settings pages. I have dd-wrt v24-sp2 on a WRT54GL. Thanks.

Edit: Oh, now I get it. It's the same as the default gateway, which for me at present is 70.36.136.1.

bbmak7

join:2004-01-11
San Francisco, CA
reply to Chair
Are you using DDWRT router? If yes, see my post for fix.

Ravenheart

join:2006-02-10
Berkeley, CA
reply to Ravenheart
I remember now that I encountered something like this years ago and came up with a command similar to Huckweed's on a DD-WRT forum.

The same forum thread offered a persistent command that could survive loss of power and soft resets:

telnet the router IP from a Windows command prompt.

Log in, and enter these commands:

nvram set rc_firewall="iptables -I INPUT -p UDP -i vlan1 --dport 68 --sport 67 --source 70.36.136.1 -j accept"
nvram commit

where from the first nvram to the second quote is one line, and the IP in the command is your default gateway.

HuckWeed

join:2011-09-20
Just be aware that sonic seems to offer subsequent DHCP renewals (after the initial IP given by the broadcast/gateway) from IPs that are often in an entirely different a or b class subnet. This is, in fact, the root of this particular problem for most of the firmwares that i've encountered so far that have had an issue.

To be honest, I don't understand sonic's position here, even after Dane's clarification. I would think that with not too much trouble, a competent network engineer could devise a more elegant and less disruptive solution, especially given the rather weak argument for renewing the IP lease every five minutes. The only logical reason I can see to continue doing things in this manner is to upsell the static ip offerings (that are considerably more expensive) that sonic offers. Not the type of behavior I would expect from an upstanding company like Sonic.net.

Anyhow, I should probably be quiet. I don't see sonic changing this just because of some 'internet forum thread' such as this one, and I'll just alienate myself, or worse yet, get banned in some capacity if I press this issue further.


CCNnorthcali

join:2004-03-07
San Francisco, CA
A single static IP is now free for residential Fushion. You might want to try that out.


DaneJasper
Sonic.Net
Premium,VIP
join:2001-08-20
Santa Rosa, CA
kudos:9
reply to HuckWeed
You'll see a few changes in the pipeline. One, as noted, was that now we offer static IPs, with a single IP static being free for residential users on Fusion.

The other is a shift to a new DHCP architecture, and a move away from short leases. The short lease was important in our older infrastructure, as the secured-ARP in the Redback SMS didn't work unless it participated in the lease - so a reboot meant an average of 1/2 the lease time until all customers came back online. Short lease, short downtime.

The Adtran platform doesn't have this limitation, it remembers IP security across reboots, so we'll be extending the lease time a lot in the new deployment.

THAT said, your firewall IS broken if it won't allow a renewal. With a longer lease interval, it'll just mean a brief downtime every 12 hours or something, but it'll still cause you an outage.

-Dane

klui

join:2001-11-08
Castro Valley, CA
Reviews:
·SONIC.NET
reply to HuckWeed
said by HuckWeed:

Anyhow, I should probably be quiet. I don't see sonic changing this just because of some 'internet forum thread' such as this one, and I'll just alienate myself, or worse yet, get banned in some capacity if I press this issue further.

said by DaneJasper:

The Adtran platform doesn't have this limitation, it remembers IP security across reboots, so we'll be extending the lease time a lot in the new deployment.

Too funny. Hope you're not too disappointed HuckWeed.

Ravenheart

join:2006-02-10
Berkeley, CA

1 edit
reply to HuckWeed
HuckWeed, thanks for that note. (And thanks to CCNNorthcali.)

Here, I'm giving a static IP a try. That looks like one simple solution.


windraver

@sonic.net
reply to Chair
So I read this thread through and apparently this 5 minute lease is intentional?

What bothers me then is why the connection doesn't renew and it throws everything offline. I need a stable connection of my homework assignments.

At least a 1 day least would be better.

I trust sonic has a solution rather than forcing an upgrade to a single IP address? Otherwise I'm disappointed that I expected too much of this company.


leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET
said by windraver :

What bothers me then is why the connection doesn't renew and it throws everything offline.

That is a problem with the configuration of the router. If the firewall in the router blocks the renewal, then it doesn't matter that Sonic is offering to renew the lease of the dynamic IP address.

said by windraver :

I trust sonic has a solution rather than forcing an upgrade to a single IP address?

You are not being forced to upgrade to a static IP address, you are being offered a free upgrade to a static IP address if you would like it.

Fixing the firewall configuration on the router is the real fix to the problem, but upgrading to a static IP address is a very effective workaround. I think it is great that Sonic is offering this option for free.
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