Nortel Networks OPTera Metro 3500 - Manual (Page 105)

Operation, administration, and maintenance (OAM) features 2-67
Planning and Ordering Guide—Part 1 of 2 NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004
There is no flow control support on the LAN and the WAN, and no policing
and shaping is performed. Received PAUSE frames are discarded or passed
through, depending on the value of the PASSCTRL attribute. By default,
PAUSE frames are discarded.
PPP over SONET
The Point-to-Point Protocol (PPP) was designed as a standard method of
communicating over point-to-point links. PPP is defined in RFC 1661 and
RFC 1662. RFC 2615 specifies POS (PPP over SONET/SDH), the method for
encapsulating PPP in SONET. PPP is comprised of three main components:
• A method for encapsulating multi-protocol datagrams.
• A Link Control Protocol (LCP) for establishing, configuring, and testing
the data-link connection.
• A family of Network Control Protocols (NCPs) for establishing and
configuring different network-layer protocols.
PPP and HDLC
PPP is built from a subset of the standard HDLC protocol. HDLC supports
configurable ‘Address’ and ‘Control’ fields but PPP is restricted to fixed values
in the ‘Address’ and ‘Control’ fields. For an illustration of the PPP packet
format, please see
Figure 2-35 on page 2-69 .
The Information Field of the PPP frame will have a maximum size of 1592
bytes.