DLCI (10-24 bits) (Frame Relay)

Protocol: Frame Relay Frame Relay PCI

Field: data-link connection identifier

Length: 10-24 bits

Contents: virutal channel ID.

DLCI numbers identify a point-to-point link, not an end-to-end (DTE-to-DTE) service connection.

The Frame Relay header is 2 bytes in length at least with a minimum DLCI length of 10 bits. Using the address extension function, the DLCI may be 10 (2 header octets), 17 (3 header octets), or 24 bits (4 header octets) in length. The address extension is indicated by an EA bit set to one (EA=1).

LMI - Local Management Interface

If the Frame Relay PDU contains LMI data, the DLCI has a length of 10 bits (2 header octets) being set to:

DLCI = 1023 ........ LMI-Adresse

DLCI = 1019-1022 ... Multicast-Adressen

LMI supports global address schemes which means that each Frame Relay node may have a unique DLCI being addressed by address resolution. This capability enables Frame Relay to support SVCs. Though, most Frame Relay networks use PVCs.

DATA (1-4500 bytes) (Frame Relay)