Control Word - Alcatel-Lucent 7705 Service Manual

IP Interworking VLL (Ipipe) Services
In order to forward unicast frames destined for CE 1, PE 2 validates the MAC destination
address of the received Ethernet frame. It should match that of the Ethernet SAP. PE 2 then
removes the Ethernet header and encapsulates the IP packet directly into a pseudowire with
or without the optional control word. PE 1 removes the pseudowire encapsulation and
forwards the IP packet over the SAP using PPP encapsulation.
When a packet reaches the access egress and the configured SAP is over a VLAN, the node
pushes (inserts) the appropriate VLAN tag into the Ethernet frame header before forwarding
the Ethernet frame out of the port. Ethernet frames at the access egress can also be marked
with appropriate dot1 priority bits if the dot1 priority QoS profile is assigned to the
forwarding class configuration.
Ethernet frames mapped to an Ipipe service can have a maximum of two VLAN tags.
Frames with more than two VLAN tags are dropped at the Ipipe access ingress SAP.
At access ingress, PE 1 performs proxy PPP negotiation and provides the IP address of the
remote CE 3 device to CE 1 during IPCP negotiation using the IP-Address option.
A PE does not flush the ARP cache unless the SAP goes administratively or operationally
down. The PE with the Ethernet SAP sends unsolicited ARP requests to refresh the ARP
cache according to the refresh interval. ARP requests are staggered at an increasing rate if no
reply is received to the first unsolicited ARP request. The refresh interval is configurable
using the

Control Word

IP interworking VLL supports an optional control word (CW). Refer to
Word on page 190
Page 170
CLI command.
mac-refresh
for more information.
Pseudowire Control
7705 SAR OS Services Guide