Fine for 3 years - then Internal Network unavailable

N

Neill

Hi all! I'm desperate for some help!

I have two windows 2k servers running IIS and two windows 2k servers running
SQL7. All has been fine and dandy for pretty much 3 years! I've even been
boasting to my linux colleagues that my windows servers have been running
without problem for this long!

All servers have dual network cards. The webservers each have a single
external interface card (without microsoft networking client etc) which are
used by external sources (internet) to connect to the websites running on
them. Connectivity to the webservers is absolutely fine.

The webservers also each have an internal network interface card which is
used to connect to backend database servers. The aim of this being to
ensure that the database servers cannot be seen from the internet and also
to ensure "website traffic" flows over a seperate network card to "database
traffic".

The internal network cards are directly cabled to a cisco switch and
configured with IP addresses on the 10.255.1.0/24 network. No gateway is
set for the internal network cards (they all exist on the same subnet so no
need!?)

However for no reason whatsoever the servers can no longer communicate
between each other over the internal network! Database connections that use
the internal ip address of the database servers now timeout with a nasty
"[DBNETLIB] SQL server not found or access denied" error. The servers
cannot ping each others internal address, and the 10.255.1.x network
addresses arent even showing in each servers arp cache.

To try and get it working I manually added arp entries to each server, and
it appears that each server can now ping each other... However database
connections still have the same problem, so I dont think this "bodge"
attempt has resolved anything.

I must admit, I installed a whole host of windows security updates last
Sunday evening (20th Feb). I can supply the KB numbers if this is useful,
one of them included an update to WINS which is installed on the web servers
to ensure windows name resolution works ok. Everything was fine until last
Tuesday night (22nd Feb).

with thanks in anticipation

Neill
 
R

Robert L [MS-MVP]

posting the the results of all computers' ipconfig /all here may help. this step by step troubleshooting may help, http://www.howtonetworking.com/Troubleshooting/notaccessibale0.htm

Don't send e-mail or reply to me except you need consulting services. Posting on MS newsgroup will benefit all readers and you may get more help.

Bob Lin, MS-MVP, MCSE & CNE
How to Setup Windows, Network, Remote Access on http://www.HowToNetworking.com
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
This posting is provided "AS IS" with no warranties.
I recommend Brinkster for web hosting!

Hi all! I'm desperate for some help!

I have two windows 2k servers running IIS and two windows 2k servers running
SQL7. All has been fine and dandy for pretty much 3 years! I've even been
boasting to my linux colleagues that my windows servers have been running
without problem for this long!

All servers have dual network cards. The webservers each have a single
external interface card (without microsoft networking client etc) which are
used by external sources (internet) to connect to the websites running on
them. Connectivity to the webservers is absolutely fine.

The webservers also each have an internal network interface card which is
used to connect to backend database servers. The aim of this being to
ensure that the database servers cannot be seen from the internet and also
to ensure "website traffic" flows over a seperate network card to "database
traffic".

The internal network cards are directly cabled to a cisco switch and
configured with IP addresses on the 10.255.1.0/24 network. No gateway is
set for the internal network cards (they all exist on the same subnet so no
need!?)

However for no reason whatsoever the servers can no longer communicate
between each other over the internal network! Database connections that use
the internal ip address of the database servers now timeout with a nasty
"[DBNETLIB] SQL server not found or access denied" error. The servers
cannot ping each others internal address, and the 10.255.1.x network
addresses arent even showing in each servers arp cache.

To try and get it working I manually added arp entries to each server, and
it appears that each server can now ping each other... However database
connections still have the same problem, so I dont think this "bodge"
attempt has resolved anything.

I must admit, I installed a whole host of windows security updates last
Sunday evening (20th Feb). I can supply the KB numbers if this is useful,
one of them included an update to WINS which is installed on the web servers
to ensure windows name resolution works ok. Everything was fine until last
Tuesday night (22nd Feb).

with thanks in anticipation

Neill
 

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