Dell PowerVault ME4 Series Storage System Administrator’s Guide

Using SLP

ME4 Series storage systems support Service Location Protocol (SLP, srvloc), which is a service discovery protocol that allows computers and other devices to find services in a LAN without prior configuration. SLP is open for use on all operating systems, and does not require formal licensing.

SLP is based on User Datagram Protocol (UDP) and can use Transmission Control Protocol (TCP) if needed. SLP listens on port 427. When a client, or User Agent (UA), connects to a network, the client queries for Directory Agents (DA) on the network. If no DA responds, the client assumes a DA-less network and sends a multicast UDP query. All Service Agents (SA) that contain query matches will send a UDP answer to the client. If the answer message is too large, the client can repeat the query using TCP.

In a network with DAs, each SA must register all services with a DA. Then the clients will query the DAs, who will respond to the query with its cached SA information.

Through use of DAs, SLP can also scale beyond the local area network to large enterprise, which is an enterprise IT issue. Consult the IETF RFC2165.

When SLP is enabled, the storage system will advertise the interfaces shown in Table 1 and populate the configuration attributes shown in Table 2.

You can enable or disable the SLP service in the PowerVault Manager, as described in Enable or disable system-management settings, or by using the CLI set protocols command, as described in the Dell PowerVault ME4 Series Storage System CLI Guide.

If the SLP service is enabled, you can test it by using an open source tool, such as slptool from www.openslp.org.