?
Solved

Exchange 2007 - SMTP Connectors and cost weighting

Posted on 2009-04-21
6
Medium Priority
?
1,625 Views
Last Modified: 2012-05-06
Hi,

The flow of outbound messages are as follows:

Exchange 2007 -> MTA(IronPort) -> Internet

There are 2 MTAs and I wanted to know what happens if I set up 2 equally weighted SMTP Connectors on the Exchange 2007 server pointing to each of the MTAs. Will Exchange "load share" or round robin between the two MTAs?

What if I set up one SMTP Connector with a higher priority pointing to MTA-A and the lower priority SMTP Connector to MTA-B. If MTA-A becomes unavailable, will Exchange automatically start forwarding messages outbound via MTA-B? What if there are queued messages that were pending for MTA - A just before it went down. Will those messages just wait and Exchange will retry or is Exchange smart enough to re-queue them to go out MTA-B?

Thanks for any and all help.
0
Comment
Question by:bcmchong
  • 3
  • 3
6 Comments
 
LVL 65

Expert Comment

by:Mestha
ID: 24197240
If you have two MTAs the same, I would just put both on to the same Send Connector. They will then load balance. I wouldn't have two Send Connectors.

On the cost basis - if you have two connectors, one with cost 1 and one with cost 2, and the address space is the same on both, then cost 2 will not be used, because the first connector is lower cost. The email will just queue.

Have you read the Technet article on Load Balancing and Fault Tolerance for Hub Transport?

Simon.
0
 

Author Comment

by:bcmchong
ID: 24197413
Hi Simon,

No I have not. I will definitely take a look at it.

To your point, if there are two connectors, the one with cost 2 will not be used - even when the one with cost 1 is unavailable or down?

You mentioned that if I were to put both on the same Send Connector, they will load balance. What if one of the MTAs becomes unavailable, will it fail over to the other? What of the messages that were queued for the one MTA that became unavailable, will Exchange "re-queue" them for the other MTA that's still up?

Thanks.
0
 
LVL 65

Expert Comment

by:Mestha
ID: 24199517
The whole point of load balancing is that if one becomes unavailable, the other one takes over - as long as both smart hosts are on the same Send Connector.

Now if the authentication credentials required for each smart host were different, then you would use two different Send Connectors, but with the same cost - again they would load balance.

When the costs are not the same, they don't load balance. Exchange will not try another connector because the lowest one matches.

Simon.
0
Transaction-level recovery for Oracle database

Veeam Explore for Oracle delivers low RTOs and RPOs with agentless transaction log backup and transaction-level recovery of Oracle databases. You can restore the database to a precise point in time, even to a specific transaction.

 

Author Comment

by:bcmchong
ID: 24200904
Can you please address fault tolerance/failover? If they are on the same Send Connector, will Exchange failover if one MTA drops off?

If they are on different Send Connectors, will Exchange failover automatically? And with different Connectors, is the requirement that they be equally weighted?

Thanks.
0
 
LVL 65

Accepted Solution

by:
Mestha earned 2000 total points
ID: 24202695
I thought I had already stated what happens above?
If you have two connectors which are not at the same cost, then you do not get load balancing, which means by definition you will not get fault tolerance. Exchange simply will not try another connector of higher cost unless the lower cost connector does not have the domain that it wants to use listed.

So if the connector with cost of 1 had example.com and the connector with cost 2 had *, then all email for anything other than example.com would go out through connector with cost of 2.
However if connector 1 had * and a cost of 1 and connector 2 had * and a cost of 2, then all email would try and use connector 1 and connector 2 would be ignored.

Otherwise, which bit of this line isn't clear:

"The whole point of load balancing is that if one becomes unavailable, the other one takes over - as long as both smart hosts are on the same Send Connector. "

Simon.
0
 

Author Comment

by:bcmchong
ID: 24204699
It is clear to me now. Thanks for your patience.
0

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Steps to fix “Unable to mount database. (hr=0x80004005, ec=1108)”.
Steps to fix error: “Couldn’t mount the database that you specified. Specified database: HU-DB; Error code: An Active Manager operation fail”
The viewer will learn how to simulate a series of sales calls dependent on a single skill level and learn how to simulate a series of sales calls dependent on two skill levels. Simulating Independent Sales Calls: Enter .75 into cell C2 – “skill leve…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an antispam), the admini…
Suggested Courses

831 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question