This means up to 10 separate copies of the message must be routed to the next hop.
Now, if it is possible to bifurcate the message further down the route, it is easy to see how much bandwidth
could be saved.
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Exchange Server 2007 tries to bifurcate, or fan - out, as late in the routing as possible to save network
traffic. If two or more recipients have different destinations, but the least cost paths share some hops, the
message fans out on the hop before the paths diverge. It is not possible to configure or alter delayed
fan - out settings.
Figure 11 - 4 shows an example of delayed fan - out. A user in Site A, sends a message to three recipients.
Christine is in Site D, and Isabel and Madison are in Site E. A single copy of the message is sent to Site B,
where it is split for delivery. From Site B, a direct delivery is made to Christine in Site D, and Isabel and
Madison in Site E.
Figure 11-4
Routing Troubleshooting
As explained at the beginning of this chapter, there must be at least one functioning Hub Transport
server in each Active Directory site where there is a mailbox server. A few key events are logged when
there are issues with a Hub server.
Common Errors
The following table lists common errors related to routing that are logged to the Windows Application log.
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