VLL services provide IP connectivity between a host attached to a point-to-point access circuit (FR, ATM, PPP) with routed PDU encapsulation and a host attached to an Ethernet interface. Both hosts appear to be on the same IP interface. This feature is supported only for IPv4 payload.
In deployments where it is not practical for operators to obtain and configure their customer CE address, the following behaviors apply:
A service comes up without prior configuration of the CE address parameter under both the SAP and the spoke-SDP.
Operators rely solely on received ARP messages from the Ethernet SAP-attached CE device to update the ARP cache with no further check of the validity of the source IP address of the ARP request message and the target IP address being resolved.
The LDP address list TLV signaling the learned CE IP address to the remote PE is supported. This is to allow the PE with the FR SAP to respond to an invFR ARP request message received from the FR-attached CE device. Only Ethernet SAP and FR SAP can learn the CE address through ARP and invFR ARP, respectively. The 7450 ESS and 7750 SR do not support invATM ARP on an ATM interface.