Multisite Design Questions with Poor Connectivity   

Hello:

We are considering an Exchange 2007 deployment but are concerned about its 
practical feasibility. We have four offices with roughly 25 people in each. 
Each office is in a different country, in some cases with very poor connectivity 
between sites (very high latency). We would like to maintain a single corporate 
domain name for email addressing (company.com), though some have suggested 
separate domains for each country. The underlying AD structure uses a single 
Forest and single Domain (company.local).

A single-server deployment test has failed miserably with Outlook taking 
several minutes to send a single message with a small attachment using "RPC 
over HTTPS". So now we are looking at servers in each location.

With a single public domain name, is traffic between sites more efficient? 
Using single instances for multiple recipients? Is there any additional compression 
or improvement between sites? (Basically, would this help overcome the IP 
latency issues?)

With a single public domain name, would all mail from the Internet need to 
arrive at a single point and then get distributed by Exchange?

With multiple public domains, would users still be able to take advantage 
of Calendar and Task sharing across sites? (They would still have the same 
AD domain name.)

Many thanks.

date: Thu, 24 Apr 2008 19:53:52 +0000 (UTC)   author:   MS Poster

RE: Multisite Design Questions with Poor Connectivity   

Hi 
see answers below

Henry


"MS Poster" wrote:

> Hello:
> 
> We are considering an Exchange 2007 deployment but are concerned about its 
> practical feasibility. We have four offices with roughly 25 people in each. 
> Each office is in a different country, in some cases with very poor connectivity 
> between sites (very high latency). We would like to maintain a single corporate 
> domain name for email addressing (company.com), though some have suggested 
> separate domains for each country. The underlying AD structure uses a single 
> Forest and single Domain (company.local).
> 
> A single-server deployment test has failed miserably with Outlook taking 
> several minutes to send a single message with a small attachment using "RPC 
> over HTTPS". So now we are looking at servers in each location.
> 
> With a single public domain name, is traffic between sites more efficient? 
> Using single instances for multiple recipients? Is there any additional compression 
> or improvement between sites? (Basically, would this help overcome the IP 
> latency issues?)

[Henry] a mail from site a to multiple recipients in site b is transferred 
only once. so yes, it is more eficient. (but there is no built-in compression)


> 
> With a single public domain name, would all mail from the Internet need to 
> arrive at a single point and then get distributed by Exchange?

[Henry] the routing is handled by Exchange. You can have all your recipients 
within a singel smtp domain name space.


>
> With multiple public domains, would users still be able to take advantage 
> of Calendar and Task sharing across sites? (They would still have the same 
> AD domain name.)

[Henry] Although it is not necessary, if your recipients have different mail 
domains, Exchange features are all available.
But: for some features (i.e. Autodiscover) it is more complex and / or more 
costly. 

> 
> Many thanks.
> 
> 
>

date: Sun, 27 Apr 2008 01:56:00 -0700   author:   Henry

Re: Multisite Design Questions with Poor Connectivity   

Answers inline.
-- 
Ed Crowley MVP
"There are seldom good technological solutions to behavioral problems."
.

"MS Poster"  wrote in message 
news:b3173d72acf58ca7421622ebc0e@msnews.microsoft.com...
> Hello:
>
> We are considering an Exchange 2007 deployment but are concerned about its 
> practical feasibility. We have four offices with roughly 25 people in 
> each. Each office is in a different country, in some cases with very poor 
> connectivity between sites (very high latency). We would like to maintain 
> a single corporate domain name for email addressing (company.com), though 
> some have suggested separate domains for each country. The underlying AD 
> structure uses a single Forest and single Domain (company.local).
>
> A single-server deployment test has failed miserably with Outlook taking 
> several minutes to send a single message with a small attachment using 
> "RPC over HTTPS". So now we are looking at servers in each location.
>
> With a single public domain name, is traffic between sites more efficient?

If each site has its own Internet connection, then no.  Mail would route to 
the central location and then traverse over the slow network link to the 
proper site, whereas with multiple sites the mail goes straight to the right 
location.  Exchange routing doesn't care about domain names for recipients 
in AD.

> Using single instances for multiple recipients?

Do you mean separate a domain for each location?  If so, then I answered 
that above.

> Is there any additional compression or improvement between sites? 
> (Basically, would this help overcome the IP latency issues?)

SMTP will work fine over very high latency.  It was designed in a time where 
computers were connected by 300-baud acoustic modems.

> With a single public domain name, would all mail from the Internet need to 
> arrive at a single point and then get distributed by Exchange?

It doesn't have to.  For example, if another site has a direct Internet 
connection it could be an alternate MX record for redundancy.

> With multiple public domains, would users still be able to take advantage 
> of Calendar and Task sharing across sites? (They would still have the same 
> AD domain name.)

You can have as many SMTP domains as you want and it has no effect 
whatsoever on Exchange's feature set as long as you set up recipient 
policies properly.

> Many thanks.
>
>

date: Sun, 27 Apr 2008 19:53:31 -0400   author:   Ed Crowley [MVP]