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Connection repeatedly dropping
2 Attachment(s)
Hi there,
I have been a VM customer for years and until recently was on 20Mbit. I came back from holiday and then my connection kept dropping. An engineer came around and installed a SuperHub, which I use in modem only. The same symptoms were exhibited just a day or two later. An engineer came around again and installed a SuperHub 2 and changed some connections outside. I am running the SuperHub 2 as a Modem only. This goes in to my Linux server. On this box I have DHCP, DNS and iptables to masquerade the connection and forward it on to clients. The VM engineer that came around last time was a Supervisor and said that as I was using my own equipment, they were unable to see what is going wrong. I fail to understand why this is the case. The SuperHub is still at the forefront of the network, so they should be able to get their readings just fine. I wasn't too impressed with him. The other engineer was able to put me into modem only mode wirelessly, so that I did not need to physically connect the SuperHub and accidentally double NAT myself. The other 'Supervisor' spent around 10 minutes trying to login to 192.168.1.1 and then 'refused' to assist because I have a server. One thing I would like some clarification with: he said that because he was reading no T(x) timeouts, the system was fine. Are these timeouts persistent across reboots in the SuperHub? He told me that they were, and that it meant my connection was perfect. But I really don't believe this... Nonetheless, during periods of downtime, I have attached the cable directly in to a Windows PC, just to make sure things are normal, but have not had any improvement either. My symptoms are that the network just 'drops' offline. During this time, a ping to 8.8.8.8 will return me a 'Host destination unreachable'. I am unable to ping 192.168.100.1 (the SH in Modem Only mode) or resolve the page either during this time. I have noticed from running tcpdump on 67 that Virgin Media's DHCP servers seem extremely slow to respond to discovers. My guess would be that the SNR is dropping temporarily, then my SH is taking a long time to resynchronise with the network. I noticed that removing the coax from the SH and reconnecting it will not result in automatically re-establishing the connection, so this may support this idea. This has been going on for two weeks now and is quite frustrating. I want this fixed, but I'm not sure how to diagnose this one. Connection went down typing this... Here are my numbers when my connection is up. I have a 6Db FPA on my SH. Here is my routing information. My IP is: 82.14.218.xxx Code:
Kernel IP routing tableCode:
post-up route add default gw 82.14.218.1Many thanks, Sam |
Re: Connection repeatedly dropping
Quote:
You could check RouterStatus > Information > Software Version Then head over to VM Community Help & Support Website. and search for "2.01.03 DHCP" eg DHCP-seems-broken-since-upgrade-to-V2-01-03 Worth checking out anyway. |
Re: Connection repeatedly dropping
Cable Modem EuroDOCSIS 3.0 Compliant
Serial Number 4831XXXXXXXXX Boot Code Version PSPU-Boot 1.0.20.1391 Software Version V1.01.11 Hardware Version 1.03 CA Key Installed My model is a Super Hub VMDG490. Looks to be a Netgear, and came with the GPL license information, but I can't find the *complete* source code anywhere so I can't even dig in to what may be happening myself. What are the usual timeframes on these kind of fixes? I can be on another ISP by the end of the week... Sam ---------- Post added at 18:28 ---------- Previous post was at 18:25 ---------- Looks like I am on a Superhub 2ac. Sorry for not being clear S |
Re: Connection repeatedly dropping
Quote:
cpc3-croy21-2-0-cust512.19-2.cable.virginm.net [82.14.218.1] Your gateway is 82.14.216.1 (note your subnet mask - 255.255.252.0) You can also see that one of your default routes is set correctly at this (cpc3-croy21-2-0-gw.19-2.cable.virginm.net) |
Re: Connection repeatedly dropping
Quote:
Sam ---------- Post added at 19:34 ---------- Previous post was at 19:22 ---------- Quote:
route -n shows: 82.14.218.1 which resolves to cpc3-croy21-2-0-gw.19-2.cable.virginm.net That route does not show as default unless I manually add with route add default gw... Sam |
Re: Connection repeatedly dropping
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Name: cpc3-croy21-2-0-gw.19-2.cable.virginm.net Address: 82.14.216.1 How are you performing the lookup? (host entry?) |
Re: Connection repeatedly dropping
I have muddled my above post. 216.1 is correctly resolving to the gateway.
I changed the default routes, and I am still online. I'll see what happens overnight.. Sam |
Re: Connection repeatedly dropping
routing stuff aside, the power levels you posted are absolutely fine and the tech was referring to T3 and T4 timeouts of which you have none.
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Re: Connection repeatedly dropping
Yes it's stable now.
Sam |
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