### TechNote

Number: 03403-03
Date: October 1994

### What does an MLID do?

The MLID (Multiple Link Interface Driver) layer hides the complexity of the hardware from the LSL (Link Support Layer). The MLID layer consists of one or more MLIDs. Each MLID is responsible for a different type of physical network; for example, token-ring, Ethernet, FDDI, or Arcnet.

The MLIDs are LAN drivers that have an ODI interface. Madge Networks provide the following three MLIDs for Madge Smart Ringnodes:

- MADGEODI.COM for DOS
- MADGEODI.SYS for OS/2
- SMART386.LAN for NetWare 386

Each MLID can support a number of physical LAN adapters. In addition, an MLID may provide a facility known as multiple frame types. Frame types allow you to use various types of physical header on the same physical LAN adapter. The physical header is the first few bytes of the frame and usually includes a destination address, source node address, and a protocol identifier among other things. Novell defines a wide range of frame types to cope with the various physical headers available with token-ring, Ethernet, FDDI, Arcnet, and others.

The MLID takes the PID (Protocol ID) from the protocol's request frame and uses this to create a frame for transmisson. All frame type requests have a 6-byte PID. The PID is a unique byte sequence that defines the protocol..