How SLP uses multicasting

  • 10024579
  • 1.0.48598980.2486300
  • 07-Jan-2000
  • 11-Oct-2001

Archived Content: This information is no longer maintained and is provided 'as is' for your convenience.

Goal

How SLP uses multicasting

Fact

Novell NetWare 5.0

Novell NetWare 5.1

Fix

SLP uses 2 different Multicast addresses.  These are used by UA's, SA's, and DA's to dynamically discover each other.  This is the default configuration of SLP.  The Multicast address for requests to SA's is 224.0.1.22.  The Multicast address for requests to DA's is 224.0.1.35.  When a user agent is not aware of any directory agents, it will send a Multicast request to 224.0.1.22 asking for service information.  Each SA on the network must then respond even if it cannot provide the information the UA is requesting.

A UA or SA will send a Multicast packet to 224.0.1.35 when attempting to discover a Directory Agent.  Once a UA or SA knows the address of a DA it will unicast all service registration requests and service information requests to the DA.  If a UA or SA is configured with the address of a DA (via DHCP or static configuration) they will not, in most cases, send out any Multicast packet.

On each NetWare 5 client and server it is possible to change the configuration of the Multicast Radius (also known as hop count or TTL).  The default is 32.  You can change this all the way down to 1 (one).  This can be used to help eliminate Multicast storms.  Changing the Multicast radius to 1 means that all Multicast packets will only cross one router and then be dropped.