Miscommunication through CISCO routers after migration from Win NT to Win 2003

Dear Sirs,

After upgrading a domain from Win NT to Win 2003 all the client computers from the subnets are unable to log on to the domain. The clients on the same network segment as the Domain Controller have no problems. All the communication to/from the other segments passes through the following CISCO routers: 7200vxr and 2600.

TCP-IP is traffic is not affected.

Any idea what protocols and TCP/UDP ports should be allowed for proper communication and authentication?

Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Win2003 domain is 100% dependent on properly configured DNS and having the clients auto-register themselves in DNS just like they did with WINS. Clients must point to this internal DNS server as primary in order to find the server, and the SRV records must be there.

You might want to setup a WINS server at least temporarily if all of your client workstations are not up to XP..
Keith AlabasterEnterprise ArchitectCommented:
Has anything else changed in your setup?
By tcpip traffic, I assume that you can ping by ip address and name to the domain server(s).
Are any dhcp-set work stations on the associated subnets picking up the correct settings such as IP, mask, gateway, dns servers?
MenshenAuthor Commented:

We solved the problem thanks. DNS and WINS were always available.
We realized we had to change the MTU size on the router... I guess AD authentication in 2003 R2 is more sensitive to changes on the packets.
What kind of communications lines do you have, and what did you have to change the MTU size to ?

thanks for the update!
PAQed with points refunded (450)

Community Support Moderator

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Software Firewalls

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.