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Exchange 2003 Layout

kingcastle
kingcastle asked
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Last Modified: 2013-12-14
Hi All
We have 6 sites in our company, at HQ we have 10 servers all running windows 2003 and 1 exchange server 2003. HQ runs about 75 really heavy email users, email is the main app of the company. We have vpn tunnels setup to the other sites via dsl links and these sites have DC/GC each. These other sites are currently running no email apps but we would like to host all mail on the central exchange server. We expect the other sites to be equally heavy email users but the most users per remote sites will be 15 max. The dsl links range from 2mb down to 8mb down but all have 512mb up.

Whats peoples experience of consolidating exchange services to HQ? I mean what if a user at site2 sends a 7MB email to 10 "internal users" all in different sites what way is that mail routed? does it all have to come down the 512mb tunnel to HQ ad then back out?

ta
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tigermattSite Reliability Engineer
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Commented:
512Mbps uplink? UPLINK? I'm guessing you mean 512Kbps uplink... because 512Mbps is half a gigabit per second, which is virtually impossible at present.

Anyway, back to your actual question. All the mail which is sent has to traverse the VPN connection back to the Exchange Server in HQ. When the user who's mailbox that message resides on logs in, the message must then be transferred back down the VPN to their appropriate site.

Consolidation of email to HQ isn't a bad option, because it means there is less management, cost and complexity involved. However, particularly since email is the most important system in the company, you have to consider the downtime which could be caused if the link to HQ ever went down, users weren't able to access their email and the performance loss of all this VPN activity.

From what I've done with email consolidation, I've found that it is a good idea to work out the sites with the heaviest Exchange users. I've then placed another Exchange Server in those remote sites, perhaps on the DC/GC there if hardware is an issue. Once the mailboxes are moved over to that Exchange Server, you effectively enable users to access their mailboxes locally, and only mail which has to go to other users in the company will end up going back to HQ for the other recipients.

> what if a user at site2 sends a 7MB email to 10 "internal users"

Since the only Exchange Server is located in the HQ, the 7MB email will be transmitted once across the 512Kbps upload to the Exchange Server for processing. Everything has to pass through Exchange. The message will then traverse back down the VPN line to the appropriate Outlook mailbox, when the recipient opens up Outlook next.

> all in different sites what way is that mail routed

The message will sit on the Exchange Server in HQ until the user opens up Outlook. Cached Exchange Mode is a must in these environments; at least then the only data going across the VPN is new mail arriving at a user's mailbox and a user sending a new message. A cached copy of all mail is otherwise kept locally on their machine, so when they have to open up that 20MB attachment, it opens locally, rather than over the VPN.

I hope this answers your questions, please post back if you have any more as a result of this :-)

-tigermatt

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Commented:
hi thanks for your detailed response. if i have two or more exchange servers, does that mean that all incoming mail will come into one specified server and then distributed to the others and will all outgoing mail go through the relevant exchange server without having to go through the main exchange server so to speak.

ta
tigermattSite Reliability Engineer
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Most Valuable Expert 2011

Commented:
It depends on your configuration. If you just add an additional Exchange Server and don't change your MX records, then all the mail will still go through your first server. However, if you were to change that configuration so that two servers were on the MX records with equal preference, mail could go to either of the two servers, and then either be delivered locally there or still have to traverse the VPN to the other server.

There's no way of telling incoming mail which server to go to based on the recipient of the message. This routing has to be done after the mail is received, but Exchange does it automatically no matter which server the mail arrives on.

> all outgoing mail go through the relevant exchange server

This gets complicated. If a user's mailbox is on another Exchange Server, then provided that server is a bridghead and you have checked the outgoing SMTP connector configuration on that server, then mail should pass out directly from that server. Obviously if a user's mailbox is hosted on a different server to their local one, the mail will still have to go to that server before it is sent out.

-tigermatt

Author

Commented:
ok sorry about this but if thats the case im struggling to see the benefit of having exchange servers in each site if at the end of the day an incoming and outgoing mail still has to traverse the vpn tunnel to be delviered.

ta
tigermattSite Reliability Engineer
CERTIFIED EXPERT
Most Valuable Expert 2011

Commented:
The benefits of having an Exchange Server in each site - or even just your sites with the heaviest users - are that you will save on VPN traffic for mail travelling locally on that server. Users whose mailboxes are on that server will be able to access their mailbox locally on the server too, meaning that VPN traffic is reduced there.

By configuring each server on your MX records, you will also have a little redundancy. If one server is offline for any period of time, the other server can accept any incoming email and either deliver it to a local mailbox, or queue it until the remote server is brought back up.

And as I've said, you CAN configure a local Exchange Server to send out outbound mail itself, provided it is a bridghead.

-tigermatt

Author

Commented:
ok last point i promise, if i have all users in remote sites running cached mode is that not the same thing? the only problem being mail traversing the vpn tunnel?

ta
tigermattSite Reliability Engineer
CERTIFIED EXPERT
Most Valuable Expert 2011

Commented:
I guess you could say that it is the same thing, sort of. The only difference is that all the transactions which they make against their mailbox still have to traverse the VPN, whereas if users have a local Exchange Server, no internal mail to users on that same server must traverse the VPN, outbound mail doesn't have to traverse the VPN etc.

Cached mode essentially means there is a copy of their mailbox stored on their local workstation, and in any scenario, it is always a good idea to run Outlook in this manner.

-tigermatt

Author

Commented:
so what do you reckon more than one exchange just to be on the safe side or run cached mode?
if i go with multiple exchange servers how do i configure the remote site exchanges so they can send outbound mail without having to go through the main exchange ie how do i configure in bridgehead mode the remote exchange servers?

also are you sure you can run exchange 2003/2007 on a DC

Author

Commented:
what size can the cached mode local file grow to?
Site Reliability Engineer
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Commented:
This one is on us!
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