ng_pred1 man page on FreeBSD

Man page or keyword search:  
man Server   9747 pages
apropos Keyword Search (all sections)
Output format
FreeBSD logo
[printable version]

NG_PRED1(4)		 BSD Kernel Interfaces Manual		   NG_PRED1(4)

     ng_pred1 — Predictor-1 PPP compression (RFC 1978) netgraph node type

     #include <sys/types.h>
     #include <netgraph/ng_pred1.h>

     The pred1 node type implements the Predictor-1 sub-protocols of the Com‐
     pression Control Protocol (CCP).

     The node has two hooks, comp for compression and decomp for decompres‐
     sion.  Only one of them can be connected at the same time, specifying
     node's operation mode.  Typically that hooks would be connected to the
     ng_ppp(4) node type hook of the same name.

     This node type supports the following hooks:

     comp    Connection to ng_ppp(4) compress hook.  Incoming frames are com‐
	     pressed and sent back out the same hook.
     decomp  Connection to ng_ppp(4) decompress hook.  Incoming frames are
	     decompressed and sent back out the same hook.

     Only one hook can be connected at the same time, specifying node's opera‐
     tion mode.

     This node type supports the generic control messages, plus the following:

     NGM_PRED1_CONFIG (config)
	  This command resets and configures the node for a session (i.e., for
	  compression or decompression).  This command takes a struct
	  ng_pred1_config as an argument:

	  struct ng_pred1_config {
		  u_char	  enable;		  /* node enabled */
	  The enable field enables traffic flow through the node.

     NGM_PRED1_RESETREQ (resetreq)
	  This message contains no arguments, and is bi-directional.  If an
	  error is detected during decompression, this message is sent by the
	  node to the originator of the NGM_PRED1_CONFIG message that initi‐
	  ated the session.  The receiver should respond by sending a PPP CCP
	  Reset-Request to the peer.

	  This message may also be received by this node type when a CCP
	  Reset-Request or Reset-Ack is received by the local PPP entity.  The
	  node will respond by flushing its compression state so the sides can

     NGM_PRED1_GET_STATS (getstats)
	  This control message obtains statistics for a given hook.  The sta‐
	  tistics are returned in struct ng_pred1_stats:

	  struct ng_pred1_stats {
		  uint64_t	  FramesPlain;
		  uint64_t	  FramesComp;
		  uint64_t	  FramesUncomp;
		  uint64_t	  InOctets;
		  uint64_t	  OutOctets;
		  uint64_t	  Errors;

     NGM_PRED1_CLR_STATS (clrstats)
	  This control message clears statistics for a given hook.

     NGM_PRED1_GETCLR_STATS (getclrstats)
	  This control message obtains and clears statistics for a given hook.

     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when hook have been disconnected.

     netgraph(4), ng_ppp(4), ngctl(8)

     D. Rand, PPP Predictor Compression Protocol, RFC 1978.

     W. Simpson, The Point-to-Point Protocol (PPP), RFC 1661.

     Alexander Motin ⟨⟩

     Due to nature of netgraph PPP implementation there are possible race con‐
     ditions between data packet and ResetAck CCP packet in case of packet
     loss. As result, packet loss can produce bigger performance degradation
     than supposed by protocol.

BSD			       December 24, 2006			   BSD

List of man pages available for FreeBSD

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net