Iain.Faulkner Posted July 31, 2013 Posted July 31, 2013 Ok, apologies in advance for what may become a long and rambling post. We're in the process of having a new network installed over the summer and have hit a fairly large problem. This is the situation, the existing network is in place and all is working. The new network is in place, all servers are up and running however at this point there is no connection to the Internet, but there is a connection to the Internet on the old network. If we bridge The two networks and connect them to each other the old servers and the new servers can see and talk to each other, however we lose our Internet connection. As soon as we remove the bridge, the Internet connection is restored and works again. Naturally with two networks, we have multiple dc's with two sets of dhcp and dns servers, two separate default gateways, however the ip ranges are the same. We've checked the ip's and there are no conflicts. I assume this is going to be a dns issue somewhere, but I've no idea on where to start to try and fix issue. Anyone got any ideas? Thanks Iain
Iain.Faulkner Posted July 31, 2013 Author Posted July 31, 2013 Proxy settings are all ok, as I say we don't make any changes other than to connect the two networks physically and it just stops working :-(
jinnantonnixx Posted July 31, 2013 Posted July 31, 2013 Are both DNS servers in sync? What does a tracert to say, BBC - Homepage tell you? Does it stop at any point? How are using a proxy - wpad/pac or set through GP? Try setting it manually to an IP address to rule out DNS glitches
walkd Posted July 31, 2013 Posted July 31, 2013 Do you loose internet access for both networks or just one?
Iain.Faulkner Posted July 31, 2013 Author Posted July 31, 2013 We lost Internet access for both networks, having run a tracert to http://www.google.co.uk, it gets through fine. We are still receiving email though which comes in through the same route.
Iain.Faulkner Posted July 31, 2013 Author Posted July 31, 2013 We've done the setting of the proxy manually and by gp and neither makes any difference.... What do you mean about the DNS servers being in sync? Do you mean do they contain the same entries?
ZeroHour Posted July 31, 2013 Posted July 31, 2013 Is the gateway ip the same for both? I think the bridge is breaking because you have the gateway set at 2 places. Try removing the gateway from old network when bridging to new network and see if they then route to the gateway for the new network. If they are all in the same subnet/range dual gateways will cause issues I *think*. 1
Iain.Faulkner Posted July 31, 2013 Author Posted July 31, 2013 Is the gateway ip the same for both? I think the bridge is breaking because you have the gateway set at 2 places. Try removing the gateway from old network when bridging to new network and see if they then route to the gateway for the new network. If they are all in the same subnet/range dual gateways will cause issues I *think*. Thanks Zerohour, unfortunately I don't think we can remove the gateway on the old network. Our old network uses our ISA box's ip as its default gateway so removing it would stop all traffic going through it as it's through the isa box that we get out to the Internet.....sorry I should have added that to my original post :-s
ZeroHour Posted July 31, 2013 Posted July 31, 2013 Thanks Zerohour, unfortunately I don't think we can remove the gateway on the old network. Our old network uses our ISA box's ip as its default gateway so removing it would stop all traffic going through it as it's through the isa box that we get out to the Internet.....sorry I should have added that to my original post :-s Could you possibly post your network config for an example server/client on each network and if anything changes after the bridge.
walkd Posted July 31, 2013 Posted July 31, 2013 If a trace works from both networks and mail is flowing, it really points to an issue with your proxy server. Do you proxy everything or just www, if you can try something you don't proxy to confirm like ftp or ssh. 1
Iain.Faulkner Posted July 31, 2013 Author Posted July 31, 2013 I'll get hold of actual configuration tomorrow and check ISA for what we actually proxy and come back. Thanks for everything so far
tonywesley Posted July 31, 2013 Posted July 31, 2013 IE 10 issue ? Try firefox or go back to IE9 IE10 does not like proxies 1
Iain.Faulkner Posted August 1, 2013 Author Posted August 1, 2013 Ok tried it again this morning, definitely not a browser issue as we've tried it with IE, chrome and Firefox.
jinnantonnixx Posted August 1, 2013 Posted August 1, 2013 (edited) ,,, What do you mean about the DNS servers being in sync? Do you mean do they contain the same entries? I'm assuming you have >1 DNS server in your new, live system. I've had a problem where one DNS server returned one address, the other DNS server returned a different one (for an internal machine). I had to delete the cached lookups. Try this nslookup server and see what address is resolved. Then server and type the name of the proxy again, check it's the same, correct, address. Edited August 1, 2013 by jinnantonnixx
jinnantonnixx Posted August 1, 2013 Posted August 1, 2013 Try a tracert to an external site when the networks are connected and when they're not. Compare the results, this should give you an indication as to what's happening.
Iain.Faulkner Posted August 1, 2013 Author Posted August 1, 2013 Try a tracert to an external site when the networks are connected and when they're not. Compare the results, this should give you an indication as to what's happening. Hi, We've run the tracert as suggested and they both come back with the same result and both seem ok
jinnantonnixx Posted August 1, 2013 Posted August 1, 2013 Hi, We've run the tracert as suggested and they both come back with the same result and both seem ok Is the proxy itself using something on the old network (try a 'route print' from the proxy) 1
Iain.Faulkner Posted August 1, 2013 Author Posted August 1, 2013 Ok, so we went right back to the drawing board with this. We separated the two networks again, and completely took apart the old/existing network shutting down all the old servers and sorting out our existing core switch. We restarted the old network and tested that everything was working.....which it was. So we reconnected the two networks....and everything remained working, and now we could get internet access on the new network as well. Very bizarre, and I still think it must have been DNS related, but at least it's all working and we can now make some serious progress! Thanks again for all the replies. Iain
cpjitservices Posted August 1, 2013 Posted August 1, 2013 Have you got a switch loop and the interface which goes to your internet is dropping off because the port is detecting a loop ? What switches have you got ?
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