Configuring Ppp Address And Control Field Compression - Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual

JUNOS 10.1 Network Interfaces Configuration Guide
For general information about tracing, see the tracing and logging information in the
JUNOS System Basics Configuration Guide.

Configuring PPP Address and Control Field Compression

For interfaces with PPP, PPP CCC, or PPP TCC encapsulation, you can configure
compression of the Data Link Layer address and control fields, as defined in RFC 1661,
The Point-to-Point Protocol (PPP). By default, the address and control fields are not
compressed. This means PPP-encapsulated packets are transmitted with two 1-byte
fields (0xff and 0x03). If you configure address and control field compression (ACFC)
and ACFC is successfully negotiated with the local router's peer, the local router
transmits packets without these 2 bytes. ACFC allows you to conserve bandwidth by
transmitting less data.
On M320, M120, and T Series routers, ACFC is not supported for any ISO family
protocols. Do not include the
ppp-options compression]
at the
NOTE: The address and control fields cannot be compressed in Link Control Protocol
(LCP) packets.
The PPP session restarts when you configure or modify compression options.
To configure ACFC, include the
interface-name ppp-options]
This configuration causes the local router to try to negotiate ACFC with its peer. If
ACFC is successfully negotiated, the local router sends packets with compressed
address and control fields. When you include the
configuration, the PPP session restarts, and the local router sends the ACFC option
in the LCP Configure-Request packet. The ACFC option informs the local router's
peer that the local router can receive packets with compression. If the peer indicates
that it, too, can receive packets with compression, then ACFC is negotiated. If ACFC
is successfully negotiated, the local router can receive packets with or without the
address and control bytes included.
To monitor the configuration, issue the
Configured options are displayed in the
Successfully negotiated options are displayed in the
In this example, both ACFC and PFC are configured, but neither compression feature
has been successfully negotiated.
132
Configuring PPP Address and Control Field Compression
—Timer code
timer
ui —User interface code
hierarchy level when you include the
[edit interfaces interface-name unit logical-unit-number]
hierarchy level, and specify
[edit interfaces interface-name ppp-options]
compression acfc;
statement at the
acfc [edit interfaces interface-name
compression statement at the
compression acfc
show interfaces interface-name
link flags field for the physical interface.
flags
statement
family iso
hierarchy level.
[edit interfaces
:
acfc
statement in the
command.
field for the logical interface.