Chapter 35. Service Location Protocol; Active Da Discovery - Lenovo ThinkSystem NE2552E Application Manual

Chapter 35. Service Location Protocol

Active DA Discovery

© Copyright Lenovo 2018
Service Location Protocol (SLP) allows the switch to provide dynamic directory
services that helps users find servers by attributes rather than by name or address.
SLP eliminates the need for a user to know the name of a network host supporting
a service. SLP allows the user to bind a service description to the network address
of the service.
Service Location Protocol is described in RFC 2608.
Note: SLP is not supported on the internal management port (MGT).
SLP defines specialized components called agents that perform tasks and support
services as follows:
 User Agent (UA) supports service query functions. It requests service
information for user applications. The User Agent retrieves service information
from the Service Agent or Directory Agents. A Host On‐Demand client is an
example of a User Agent.
 Service Agent (SA) provides service registration and service advertisement.
Note: In this release, SA supports UA/DA on Linux with SLPv2 support.
 Directory Agent (DA) collects service information from Service Agents to
provide a repository of service information in order to centralize it for efficient
access by User Agents. There can only be one Directory Agent present per given
host.
The Directory Agent acts as an intermediate tier in the SLP architecture, placed
between the User Agents and the Service Agents, so they communicate only with
the Directory Agent instead of with each other. This eliminates a large portion of
the multicast request or reply traffic on the network, and it protects the Service
Agents from being overwhelmed by too many service requests.
Services are described by the configuration of attributes associated with a type of
service. A User Agent can select an appropriate service by specifying the attributes
that it needs in a service request message. When service replies are returned, they
contain a Uniform Resource Locator (URL) pointing to the service desired, and
other information, such as server load, needed by the User Agent.
For more details on SLP configuration, see the Lenovo ThinkSystem NE2552E Flex
Switch Command Reference for Lenovo ENOS 8.4.
When a Service Agent or User Agent initializes, it can perform Active Directory
Agent Discovery using a multicast service request and specifies the special,
reserved service type (service:directory-agent). Active DA Discovery is
achieved through the same mechanism as any other discovery using SLP.
The Directory Agent replies with unicast service replies, which provides the URLs
and attributes of the requested service.
Chapter 35: Service Location Protocol
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