slp - Service Location Protocol


The Service Location Protocol (SLP) is a dynamic service discovery
protocol that runs on top of the Internet Protocol (IP). The protocol is
specified by the IETF standard-track documents RFC 2165, RFC 2608, RFC
2609; the API is documented in RFC 2614. .

There are two components to the SLP technology. The first is a daemon,
slpd(8), which coordinates SLP operations. The second is a software
library, slp_api(3SLP), through which processes access a public API. Both
components are configured by means of the SLP configuration file,

The SLP API is useful for two types of processes:

Client Applications
Services and service information can be requested
from the API. Clients do not need to know the
location of a required service, only the type of
service, and optionally, the service
characteristics. SLP will supply the location and
other information to the client through the API.

Server Processes
Programs that offer network services use the SLP
API to advertise their location as well as other
service information. The advertisement can
optionally include attributes describing the
service. Advertisements are accompanied by a
lifetime; when the lifetime expires, the
advertisement is flushed, unless it is refreshed
prior to expiration.

API libraries are available for both the C and Java languages.

SLP provides the following additional features:

o slpd(8) can be configured to function as a transparent
directory agent. This feature makes SLP scalable to the
enterprise. System administrators can configure directory
agents to achieve a number of different strategies for

o SLP service advertising and discovery is performed in scopes.
Unless otherwise configured, all discovery and all
advertisements are in the scope default. In the case of a
larger network, scopes can be used to group services and
client systems so that users will only find those services
which are physically near them, belong to their department, or
satisfy the specified criteria. Administrators can configure
these scopes to achieve different service provider strategies.

o Services may be registered by proxy through a serialized
registration file. This is an alternative to registering
services through the API. See slpd.reg(5) for more


See attributes(7) for descriptions of the following attributes:

|CSI | CSI-enabled |
|Interface Stability | Standard |
|MT-Level | MT-Safe |


slp_api(3SLP), slp.conf(5), slpd.reg(5), attributes(7), slpd(8)

Guttman, E., Perkins, C., Veizades, J., and Day, M., RFC 2608, Service
Location Protocol, Version 2, The Internet Society, June 1999.

Guttman, E., Perkins, C., and Kempf, J., RFC 2609, Service Templates and
Service: Schemes, The Internet Society, June 1999.

Kempf, J. and Guttman, E., RFC 2614, An API for Service Location, The
Internet Society, June 1999.

Veizades, J., Guttman, E., Perkins, C., and Kaplan, S., RFC 2165,
Service Location Protocol, Network Working Group, 1997.

November 17, 1999 SLP(4P)