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Strange problem with NLB on Exchange FE servers
Hi,
I have recently set up our 2 front-end and SMTP servers in an MS NLB. I gave the NLB cluster the same IP as our original mail server to avoid changing any MX records or A records for the OWA. Everything works fine except for a strange problem for which I can find no defined errors.
To test the cluster I am using telnet on the port for the SMTP service (25). This connects fine every time from outside our organisation, but for some reason the ability to connect in this method internally is distinctly sporadic.
Can anyone shed any light as to why this might be happening, or at least somewhere that I can look to find out the errors?
Additionally, I have run Ethereal on a number of clients whilst attempting the connection tothe cluster and it seems that the cluster simply does not respond to some clients internally, despite the fact that the same client can ping the cluster and connections from outside the organsiation work fine. Also, clients that can't connect at one time seem to just start working with no changes being made.
I have recently set up our 2 front-end and SMTP servers in an MS NLB. I gave the NLB cluster the same IP as our original mail server to avoid changing any MX records or A records for the OWA. Everything works fine except for a strange problem for which I can find no defined errors.
To test the cluster I am using telnet on the port for the SMTP service (25). This connects fine every time from outside our organisation, but for some reason the ability to connect in this method internally is distinctly sporadic.
Can anyone shed any light as to why this might be happening, or at least somewhere that I can look to find out the errors?
Additionally, I have run Ethereal on a number of clients whilst attempting the connection tothe cluster and it seems that the cluster simply does not respond to some clients internally, despite the fact that the same client can ping the cluster and connections from outside the organsiation work fine. Also, clients that can't connect at one time seem to just start working with no changes being made.
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Do clients on your internal network pass through a router to get to the Mail server? or is it on the same subnet?
Presumably the external device pass through a router/firewall?
it could be that the Internal devices are having trouble resolving the MAC address for the NLB (depending how it has been setup). With traffic passing through a router/firewall these devices may be resolving them correctly.
Presumably the external device pass through a router/firewall?
it could be that the Internal devices are having trouble resolving the MAC address for the NLB (depending how it has been setup). With traffic passing through a router/firewall these devices may be resolving them correctly.
ASKER
I've increased the points available on this question as it is an urgent problem.