The Truth About OpenSLP

By Donna Moyer


Editor's Note: This article is designed for network professionals who are moving their Novell networks from NetWare to OES Linux. There is a lot of conflicting information out about the differences between Novell SLP and OpenSLP. In this article, we are going to set the record straight.

By Donna Moyer


Editor's Note: This article is designed for network professionals who are moving their Novell networks from NetWare to OES Linux. There is a lot of conflicting information out about the differences between Novell SLP and OpenSLP. In this article, we are going to set the record straight.

The History: When Novell first started moving from IPX to pure IP, they needed a protocol that would allow servers and workstations to find services on the network. Enter SLP, which at the time was out as an RFC, but was not fully developed. Novell added their own touches to SLP, including having the service register services with eDirectory. Fast-forward now to Novell's purchase of SUSE Linux and their participation in open source. Today, OpenSLP adheres more closely to current standards than Novell’s modified SLP.

The Myths: There are quite a few myths going around about Novell SLP and OpenSLP. Here are the top three – and the truth about them:

  • Novell SLP and OpenSLP are incompatible. FALSE. They are both compliant with the current RFC (although Novell SLP is not 100% compliant), and they both store services in their cache. They can also both service the same scope.
  • Novell SLP DAs synch with each other but OpenSLP DAs do not. FALSE. Novell SLP DAs never synched with each other, and neither do OpenSLP DAs. When we pointed SLP DAs at each other, they only thing that happened was that they registered the services local to themselves with the other DA.
  • OpenSLP takes a really long time to register services. FALSE. The length of time for registration of services is not a problem with OpenSLP, it is an issue with the services. In this case, most of us would be worried about eDirectory.

The Problems: When a Novell SLP DA reboots, it checks eDirectory and populates its cache with services held there. But when an OpenSLP DA reboots, it does not check with eDirectory, so it needs to wait for services to register. This was not a problem in eDirectory 8.7.3, as the service registered with SLP every 9 minutes. Starting with eDirectory 8.8.2 and going forward to eDirectory 8.8.4, however, this parameter was changed to 1 hour – and it is not tunable! A second issue with OpenSLP regards the Novell client: if the first DA on its list is up, it will not move to the second one on the list to look for services even if the first DA cannot report on a given service.

The Good News: Starting with eDirectory 8.8.5, we are now able to set the time interval for eDirectory to register with SLP. For more information please see TID 7001449. Also, the OES development teams have been tasked with modifying OpenSLP to more closely mirror NetWare SLP. Look for changes in OES 2 SP 3.

Some Suggestions:

  • Keep at least one NetWare server as an SLP DA until the end of your migration.
  • If you must migrate totally to OpenSLP, migrate to eDirectory 8.8.5 and shorten the time for eDirectory to register with SLP.
  • If your DAs need to be rebooted regularly, find out why! OES Linux is extremely stable and therefore this should not be an on-going issue.

© Copyright 2010, Uptime NetManagement, Inc.

 

Article Source: http://www.uptimenmi.com/

You have my permission to reprint and distribute this article as long as it is distributed in its entirety, including all links and copyright information. This article is not to be sold or included with anything that is sold.

About the Author:
Donna Moyer is Principal/Senior Network Consultant of Uptime NetManagement, Inc. (http://www.uptimenmi.com/). Uptime is a Novell Gold Solutions partner providing technology solutions, customized training, and consulting services. If you are interested in finding out exactly what Novell can do for your business, or are seeking to maximize the benefits from your current Novell systems, call us today at 610-621-1244!

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