3Com S7906E Configuration Manual page 1437

Figure 1-2 Place of a label in a packet
Currently, the device does not support the cell mode.
LSR
A Label switching router (LSR) is a fundamental component on an MPLS network. All LSRs support
MPLS.
LSP
A Label switched path (LSP) is the path along which a FEC travels through an MPLS network. Along an
LSP, two neighboring LSRs are called upstream LSR and downstream LSR respectively. In
R2 is the downstream LSR of R1, while R1 is the upstream LSR of R2.
Figure 1-3 Diagram for an LSP
An LSP is a unidirectional path from the ingress of the MPLS network to the egress. It functions like a
virtual circuit in ATM or frame relay. Each node of an LSP is an LSR.
Label distribution protocol
A label distribution protocol is a protocol used by MPLS for control. It has the same functions as a
signaling protocol on a traditional network. It classifies FECs, distributes labels, and establishes and
maintains LSPs.
MPLS supports multiple label distribution protocols of either of the following two types:
Those dedicated for label distribution, such as Label Distribution Protocol (LDP).
Those existing protocols that are extended to support label distribution, such as Border Gateway
Protocol (BGP) and Resource Reservation Protocol (RSVP).
In addition, you can configure static LSPs.
1-3
Figure 1-3,