An ID that uniquely identifies this LSR within the network. The LSR ID is typically derived from one of the LSR's IPv4 addresses. It may be used for path vector based loop detection if the signaling protocol in use implements that. A value of zero indicates that no LSR ID has been configured. In this case, the signaling protocol stack should construct a unique LSR ID from the other information that is available to it (such as IPv4 addresses). For example, DC-CR-LDP and DC-RSVP derive the LSR ID by taking the 32 low bits of the following _transport_address_ field, left padding with zeros if necessary. The LSR ID is only used to identify this LSR on IPv4 networks. See dcLmgrLsrEntityIpv6TranAddr for the equivalent field for use in IPv6 networks. The LSR ID provides the ASON SC PC ID for this node in a UNI 2.0-capable system.