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EXCHANGE 5.5 FAULT TOLERANCE

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by ilovenetworking 2 views

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SCENARIO:

Currently:

Externally hosted DNS + mailboxes on a UNIX server
SMTP addresses: first.last@techcompany.com
Exchange 5.5 server SP4 not connected to the Internet (Intra-office mail. Outlook is configured with offline folders and POP3 option to download external mail)

TRYING TO ACCOMPLISH some FAULT TOLERANCE

Windows NT 4.0 SP6a (DOMAIN: CHICAGO)
Exchange 5.5 server SP4
Internet Mail Connector (registered domain name: techcompany.com)
Do you see any problems configuring the Internet Mail Connector with this internal/external mail scenario?

SMTP: addresses of each user will be first.last@techcompany.com. IS IT NECESSARY FOR THE EXTERNAL SMTP addresses to match THE INTERNAL ONES?

1. What else needs to be done on the UNIX or Exchange Server to set up some kind of a fault tolerance in case the Exchange server goes down besides 2 MX records (the UNIX box with lower priority)

2. We are trying to have all mail directed to the Exchange server. In case it wentdown we want all the e-mails to be directed to the UNIX box. We don?t know how it will be retrieved after the Exchange server comes back on line?

3. Do we have to set up some kind of a forwarder on the mail servers (which server UNIX or Exchange?) or just to enable POP3 Internet e-mail within Outlook?

4. If forwarders are the way to go how is it going to work when the Exchange server is down? Is the forwarder going to just keep trying until the Exchange is back on line?

5. If the POP3client is the way to go how is it going to affect outgoing mail if the OFFLINE folders are enabled and the Exchange server is down. Isn?t it going to make sending outgoing (without the Exchange on line) mail impossible?

PLEASE, REPLY IF ANY OF YOU HAVE HAD ANY LUCK implementing a similar solution? Maybe, you know something better?

Thanks a lot,

Witold

2 replies

by duskos

Uh! So many questions!
I'll probably not answer all your questions, but perhaps other members will follow up.

There are several factors which impact your Exchange service design.

1. How big is your company?
2. How many sites you have?
3. What is the connectivity?

First of all I would get rid of Unix mail server and have (at least) two Exchange servers. (I apologize to Unix members). This way I would have one architecture to worry about.

There are basically two approaches in designing Exchange system. You can use larger number of smaller servers each hosting smaller number of recipients. Or you can have fewer, but more powerfull servers hosting large number of recipients. These powerfull servers would be preferrably clusters.Exchange (Enterprise edition) is cluster aware application and in case of hardware failure of one node it would fall back to a second node.
If you use many smaller servers then in case of failure, fewer users would be affected.

You may wish to have two exchange servers without recipient mailboxes on them connected to the Internet. Exchange servers without recipient mailboxes are called bridgehead servers. They can then deliver mail to Exchange servers on the Intranet. These servers on the Intranet have recipient mailboxes configured.

I work for big multinational company. We have two bridgehead servers in geographicaly distant locations. Many sites in our company have an Exchange server. The site qualifies as an Exchange site if it has 20 or more recipients.

And of course, have backup strategy and redundant hardware where you can restore your Exchange database.

You can also design some firewall protection.

I would recommend Windows 2000/Exchange 2000 configuration.

by ilovenetworking

Thanks, a lot for trying to help me, but it's a small company and they cannot afford and don't need cluster or bridgehead servers. I have heard that fault tolerance could be accomplished by the scenario I presented to you. A UNIX or any other external SMTP server has to support ETRN/TURN commands. I just need someone to tell me: YES, I have done it before and it works! and present the solution to me.

Thanks anyway!

Witold

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