Service Location Protocol
| application | SLP | ||||
| transport | UDP | TCP | |||
| Internet | IP ( IPv4 , IPv6 ) | ||||
| Network access | Ethernet |
Token bus |
Token ring |
FDDI | ... |
The Service Location Protocol ( SLP ) is a network protocol for finding resources that are offered by other computers via a TCP / IP -based network .
definition
The SLP is defined in the RFCs RFC 2608 , RFC 2609 , RFC 2614 , RFC 2165 , RFC 3059 and RFC 3082 .
functionality
The SLP is based on a three-stage concept . It divides the hosts into three corresponding classes:
- the directory agent (Engl. directory agents)
- the service agents
- and user agents.
If a host wants to offer a service in a network, this host must have a service agent. This service agent registers the service to be offered with the directory agent. The two agents communicate at defined time intervals whether the service is still available or whether there has been an address or service change. This time interval can be freely defined and is usually communicated to the directory agent by the service agent during the first registration.
If a client now needs a network service, the user agent, which must be present on the client, can ask the directory agent whether the desired service is available in the network. The directory agent then informs the user agent whether this service is available and, if so, under which network address the client can reach the service.
In most cases, communication takes place via unicast . In some cases, however, multicast may also be used. Multicast is used when a user agent or a service agent does not yet know the address of the directory agent. In this case, an SLP discover with multicast is carried out. This can be prevented by specifying the IP address of the directory agent or agents in the corresponding configuration files for both the service agent and the user agent.
For the smallest networks, however, SLP provides the small network scenario, the host (user agent) simply asks the group about the desired service, and every service agent who feels addressed then answers.
Novell has been using the NetWare version 5.x the SLP as a follow-up solution for the SAP one.