Ruling Out Network-Bound Problems


The network and how it is deployed is essential to the proper performance of an Exchange server. It is uncommon for networks to be network-bound, because 100 Mbps networks generally offer enough bandwidth for most organizations. However, with increasing message sizes and users per server, it is important to ensure the network does not become a choking point.

Use the counters listed in the following table to determine whether there is any network performance degradation.

Performance Counters for Network

Counter Expected values

Network Interface\Bytes Total/sec

Indicates the rate at which the network adapter is processing data bytes.

This counter includes all application and file data, in addition to protocol information such as packet headers.

  • For a 100-Mbps network interface card (NIC), it should be below 6–7 MB/sec.

  • For a 1000-Mbps NIC, it should be below 60–70 MB/sec.

Network Interface\Packets Outbound Errors

Indicates the number of outbound packets that could not be transmitted because of errors.

  • It should be zero (0) at all times.

Improving Network Performance

The following item describes how you can improve network performance:

  • Segment inter-server and global catalog traffic

    When there is much traffic, and therefore overhead due to packet collision, you can improve network performance by separating inter-server and global catalog traffic from client traffic. You can do this by having servers and global catalogs with dual network adapters, and by building a separate network for the communication required by servers and global catalogs.