SMS: Issues That Occur if a Site Contains Slow Links (278856)


The information in this article applies to:

  • Microsoft Systems Management Server 2.0
This article was previously published under Q278856

SUMMARY

This article describes issues that may occur if there are slow links in your site hierarchy.

MORE INFORMATION

The following information is from the Microsoft Systems Management Server (SMS) Administrator's Guide:

The subnets you include in your site should be connected with reliable links so that all resources (such as clients and site systems) in the site have a fast connection to all other site resources. As a general rule, if two subnets are separated by a slow link, do not include them both in the same site.

When you plan your site hierarchy, consider the nature, speed, and capacity of the connections between sites. Consider both the total network bandwidth (the amount of data that can be transmitted across the network) and the available network bandwidth (the amount of bandwidth that SMS can typically use). Make sure that SMS has enough available network bandwidth to perform site maintenance and other administrative functions efficiently.

Generally, computers that are connected by a slow local area network (LAN) or wide area network (WAN) link should be placed in different sites. If you have computers that are connected by a fast LAN, you can place these resources in a single site or in different sites. Unless there are valid reasons for placing them in different sites (such as capacity or management issues), consider including all LAN-connected servers in the same site.

If you do not follow these design recommendations for your site, your network can be negatively affected. The interaction of the site server, remote site systems, and client workstations can generate a high volume of network traffic. When these components are separated by slow links, this traffic can overwhelm the network.

For example, issues can occur if a site server is located across a slow link from a client access point (CAP). Because the Inbox Manager thread of SMS_Executive is responsible for keeping the CAP up to date, it communicates once an hour (at a minimum) to ensure that the contents of the CAP match the current site settings. Slow links between the site server and the remote CAP can cause Transmission Control Protocol (TCP) data packets to be dropped during the transmission. This behavior causes the data to be retransmitted. If the connection speed is insufficient for all data destined for the CAP to be transmitted successfully, Inbox Manager continually attempts to update the CAP. When the scheduled update interval passes again, Inbox Manager attempts to update the CAP again until it succeeds. This behavior may generate an extraordinary amount of traffic over the network.

To identify TCP retransmits, capture a network trace using the version of Network Monitor that is included with SMS. To do this, start Network Monitor and click the trace. On the Tools menu, click Experts, and then click TCP Retransmit. The network trace is analyzed and the number of retransmits, the original frame number and the final, successful frame is reported. If there is more than one retransmit instance reported in the capture, the site may have a slow link or a connectivity issue.
Modification Type:MinorLast Reviewed:1/14/2006
Keywords:kbConfig kbinfo kbNetTrace kbnetwork kbServer kbSMSSender KB278856
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