Dhcp Options; Ipcp; Troubleshooting And Fault Detection Services - Alcatel-Lucent 7705 Service Manual

DHCP Options

DHCP options are codes that the 7705 SAR inserts in packets being forwarded from a
DHCP client to a DHCP server. Some options have additional information stored in
suboptions.
The 7705 SAR supports the Relay Agent Information Option 82 as specified in RFC 3046.
The following suboptions are supported:

IPCP

Similar to DHCP over Ethernet interfaces, Internet Protocol Control Protocol (IPCP)
extensions to push IP information over PPP/MLPPP IES SAPs are supported. Within this
protocol, extensions can be configured to define the remote IP address and DNS IP address
to be signaled via IPCP on the associated PPP interface. The IPCP-based IP and DNS
assignment process is similar to DHCP behavior; IPCP-based IP/DNS assignment is a
natural use of PPP/MLPPP IP layer protocol handshake procedures. PPP/MLPPP connected
devices hooked up to IES can benefit from this feature for the assignment of IP and DNS to
the associated interface.

Troubleshooting and Fault Detection Services

Bidirectional forwarding detection (BFD) can be configured on the IES interface. BFD is a
simple protocol for detecting failures in a network. BFD uses a "hello" mechanism that
sends control messages periodically to the far end and expects to receive periodic control
messages from the far end. On the 7705 SAR, BFD is implemented for static routes in
asynchronous mode only, meaning that neither end responds to control messages; rather, the
messages are sent periodically from each end.
To support redundancy with fast switchover, BFD must be enabled to trigger the handoff to
the other route in case of failure.
Due to the lightweight nature of BFD, it can detect failures faster than other detection
protocols, making it ideal for use in applications such as mobile transport.
7705 SAR OS Services Guide
• circuit ID
• remote ID
• vendor-specific options
Internet Enhanced Service
Page 335