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Network problems...

Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Network problems...

Hi all
I've got a reallly weird problem.
My main PC's internet keeps dropping dead. By this i mean http, ftp, msn, etc etc etc.
Strangely i am still able to access other network resources such as shared drives, folders, Remote Desktop etc. I AM able to use the internet on the remote machines via RD.
This is extremely frustrating as it is tempermental.
It's not the switch, as the laptop is plugged into the same one - Also a switch would not stop the internet and allow other protocols.
I'm totally stumped. I've tried getting windows to repair the connection etc, no luck.
DNS lookups ARE successful, but once IE has found the IP, it is unable to connect.
I should point out I have 3 default gateways & DNS servers setup however this is THE SAME on ALL of my other machines and they are all fine.
I'm getting really frustrated as it sems to be only external traffic that is affected which suggests a software or OS error.
Any suggestions please? - I've tried all my contacts and used every bit of knowledge i have. I've exhausted everything. On this one, I'm beaten.
Please help!
I need a new signature... i'm bored of the old one!
12 REPLIES
VileReynard
All Star
Posts: 11,195
Thanks: 307
Fixes: 11
Registered: ‎01-09-2007

Re: Network problems...

Why would you need 3 default gateways?
By definition a default gateway is the default to be used if you don't have a specific routing.
I find wireshark useful for monitoring (at packet level) the traffic on a port as it gives an interpreted display of the contents of the packet. It has been ported onto windows.

Not applicable

Re: Network problems...

Have you checked that your switch isn't overheating again, or that you've not accidentally loosened one of the cables.
Wink
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: Network problems...

Hi,
I'd also be inclined to think that having the DNS for three default gateways, whilst may not be the cause of the problem, does sound a little odd.  If you're able to gain connectivity via RD, then it sounds like the problem is internal to your network.  Maybe trying fiddling around with DNS?
Not applicable

Re: Network problems...

Can't be DNS if the host is able to resolve names to IP addresses - assuming of course that it is able to resolve the addresses of sites henceforth not visited (and therefore not cached).
Having 3 gateways is OK, so long as manual metrics are applied to maintain consistency. Windows is known to apply metrics automatically with varying success/consistency (a slight blip could cause the preferred gateway to become the last one to be considered for example)
Out of preference, I'd have just one assigned at any one time, with scripts saved to easily alter the gateway when required - or use DHCP to do the graft.
There's nothing wrong with having multiple gateways configured, but they have to be configured correctly to give consistent service.
@okrzynska

How are you applying the metrics to the gateways now? Are you still leaving them to be applied automatically?
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Network problems...

Hi all
Yes I'm still using auto metric (infact I'd forgotten toi look into this since previously posting).
The thing is, all my networked machines are setup the same - 3 gateways, auto metric, static 192 ip's.
It's only this one that has the problems though. I fail to see why the metric would mess up one machine intermittently but not the others.
I'm sure there must be another process or registry setting at work here playing games...
Ideas?
I need a new signature... i'm bored of the old one!
Not applicable

Re: Network problems...

Windows should manage to get the metrics in the right order, based upon connection link speeds etc - if however, for some obscure reason, one of the gateways fails to work when it should, it'll be demoted to a lower metric.
It could be something random like this causing your intermittant rogue gateway issues.
Even if its not, manually assigning the metrics will eliminate this as a possible cause, and allow us to move on to the next stage of troubleshooting.
Community Veteran
Posts: 1,576
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Registered: ‎13-04-2007

Re: Network problems...

Being able to see all local machines means nothing as you dont need a gateway for that just a simple broadcast on the subnet.
Connecting to another pc via RDP you then use the other pc's connections not yours.
If you only have 1 internet connection then you only need 1 gateway what do the other gateways do?
From a router if you use DHCP it normally set the dns to the router which doesnt need a gateway to find.
The test is simple do a tracert to 194.119.131.66 and see were its going as this will show the gateway used.
Try removing the other gateways and just use the one to see if it fixes it a sits like dns cache if it has so many bad hits it wont use it
The only other explanation is the tcip stack is knackered and you need to rebuild it see
http://support.microsoft.com/kb/811259
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Network problems...

Hi guys
Well I've removed the other 2 default gateways (and removed them as DNS servers too) and so far everything has been hunky dory for the last 2 days (Note I'm ill and off work so i finally found the time).
My question now though, is why would it be different on that one PC and all others are completely unaffected? (I'm writing this reply on my laptop which also has 3x gateway/DNS and has no problems).
One other observation, i think the faulty machine was using cached dns lookups as when i tried domains i'd not visited for a while, it wasn't finding IP's...
I need a new signature... i'm bored of the old one!
Community Veteran
Posts: 1,576
Thanks: 3
Registered: ‎13-04-2007

Re: Network problems...

DNS cache has been a problem since win2k once a dns fails it then thinks its not there so simply doesnt  try. There are fixes for this to set the time outs etc.
I can only assume that the pcs with 3 gateways just uses the one gateway and as that works it ignores the others.
I cant work out were you get 3 gateways from if you only have 1 adsl line unless you are trying to go via another pc but there is no point.
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Network problems...

Hi sam,
Basically because i live in rented accomodation my connection can change at any point from ADSL to 56k to shared wireless etc. Therefore because i only have a router (and a usb BB modem which disconnects in the night) it's easier for me to have 3 default IP's set as default gateways and DNs servers than it is to change these settings across 7 systems when i go from BB to 56k (which is an internal modem on another machine - one of the gateways).
Comlicate this further by having wireless built into another machine and i think you can see why i have so many gateways. It just isn't worth the time or agro to go through 7 machines and reconfigure their tcp/ip evey time my connection changes. Remember my BB comes through a router to so i can't really tie that into the 56k modem machine..
It's just easier really..
I need a new signature... i'm bored of the old one!
VileReynard
All Star
Posts: 11,195
Thanks: 307
Fixes: 11
Registered: ‎01-09-2007

Re: Network problems...

I thought an ADSL connection was "always on" Grin
It would make sense to always go through the router or possibly wireless if the router is a wireless router.
Why do you need to change DNS addresses?
You could just use the PlusNet DNS addresses on all machines.

Community Veteran
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Registered: ‎10-04-2007

Re: Network problems...

Quote from: axisofevil
I thought an ADSL connection was "always on" Grin

"and a usb BB modem which disconnects in the night"
usb BB modem = turn the PC off and the ADSL is off
jelv (a.k.a Spoon Whittler)
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