Network Issues

[turbod]

Hi i was wondering if anyone could help me,

My customer has 2 Sony Vaio laptops both of which are experiencing the same problem. Basically the network is setup as follows
Main Site Fully Cat5e cabbled ADSL, Active Driectory, Exchange 2000, Symantec Firewall, DHCP, DNS, Site to Site Wireless link to
Site 2
Fully Cat5e connects to main site for Web and Mail Access, has its own DC, DNS and running Symantec Antivirus.

The two laptops will join the domain talking to server in site 2 but are unable to comunicate to a degree accross the SIte to Site link. By this they recieve an IP from the DHCP server (no relay agents being used) but then are unable to comunicate accross the link, The site to site links go straight into the Switches so no routers to worry about. Basically a ping times out, web and email dont work or data access but the client can register its DNS record itself, and nslookup works ok. There is no firewall running on the laptops and Norton Internet Security has been removed, I have installed a PCMCIA network card into the laptop and this is the same. If i use the laptops in the main site they work perfectly and can do anything including travel accross the site to site link the other way to access data etc.
I am tearing my hair out on this one. By the way I forgot to mention there are approximatly 20 other machines on Site 2 and they can do everything fine 10 of these have been set-up since the problem first occured with the laptops. I have also re-images the laptops using the sony disks.

Help Please

Dave

[JoeB.]

so many possiblities... you have check the active ip release table that it is accuratly distributed. is there a static ip set anywhere... is there any possibility that a localhost ip is still addressed in certain instances.

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Joe

[vaiodon]

Are the switches "layer 3" switches - i.e. they are IP routers.

The DNS and nslookup will work from site 2 because the local DC handles all that stuff and replicates to the other DC.

The fact that the second site has its own DC and DNS would suggest to me that both sites are separate IP sub-nets.

If you look at the output from "ipconfig /all" in a command window you should be able to determine some useful info.

Do the PC's on each site reference the same "default gateway" address. That defines the default router they talk to. If that's different between site one and two then the switches are layer 3 (what are they - Cisco 35--'s by any chance?). Ensure your Vaio's are picking up the same default gateway as their neighbours.

The other thing that should be common across all PC's on each site from the network config is the netmask. Make sure it matches that of other PC's on the same site.

It could be that the DHCP setup isn't 100% and the other PC's have some manual configuration.

That's basic stuff - sorry if you've already checked it but I'd always start from basics to troubleshoot an problem.

The firewall wouldn't be sitting in the middle of both LAN's with some rule letting only known PC's from site 2 talk to resources in site 1?

Could the wireless repeater be enforcing access control lists from site 2?

[JoeB.]

the proxies....?

[turbod]

Guys thanks for the sugestions,

I forgot to mention I have also tried static IP addresses on both laptops to no avail. All machines point to the same Default Gateway which is on site 1 and is a Symantec Firewall. It is really weird, I am going to try a few bits and pieces tommorow and i will keep you posted.

Thanks again
Dave

[vaiodon]

The wireless link is acting like a layer 2 bridge then - I'd suspect it as being the culprit.

LAN bridges should pass all network data across the link, however, they typically learn the MAC addresses of PC's on either side of them. Hence, they only pass broadcasts and traffic specifically from a site 1 PC to a site 2 PC. They only pass over the link what is necessary and they could be configured to only pass traffic from previously defined PC's.(as a security measure).

Did you configure the Wireless bridges?

[turbod]

The wireless link is acting like a layer 2 bridge then - I'd suspect it as being the culprit.

LAN bridges should pass all network data across the link, however, they typically learn the MAC addresses of PC's on either side of them. Hence, they only pass broadcasts and traffic specifically from a site 1 PC to a site 2 PC. They only pass over the link what is necessary and they could be configured to only pass traffic from previously defined PC's.(as a security measure).

Did you configure the Wireless bridges?

No it was inplace after i joined. The only thing i dont get though is why the other 5 laptops have been fine?
I tried again today on differant parts of the network but still no luck. I am going to try to rebuild the laptop with a clean copy of XP and see if that does the trick, as i still feel it could be in the build.