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NG_CISCO(4)		     Kernel Interfaces Manual		     NG_CISCO(4)

NAME
     ng_cisco -- Cisco HDLC protocol netgraph node type

SYNOPSIS
     #include <sys/types.h>
     #include <netinet/in.h>
     #include <netgraph/ng_cisco.h>

DESCRIPTION
     The  cisco node type performs encapsulation and de-encapsulation of packets
     using the Cisco HDLC protocol.  This is a fairly simple  protocol	for  the
     transmission  of  packets across high speed synchronous lines.  Each packet
     is prepended with an Ethertype, indicating the protocol.  There is  also  a
     "keep alive" and an "inquire" capability.

     The  downstream  hook should connect to the synchronous line.  On the other
     side of the node are the inet, inet6, atalk, and ipx hooks, which	transmit
     and  receive raw IP, IPv6, AppleTalk, and IPX packets, respectively.  Typi-
     cally  these  hooks  would  connect  to  the  corresponding  hooks  on   an
     ng_iface(4) type node.

IP Configuration
     In  order to function properly for IP traffic, the node must be informed of
     the local IP address and netmask setting.	This is because the protocol in-
     cludes an "inquire" packet which we must be prepared to answer.  There  are
     two ways to accomplish this, manually and automatically.

     Whenever	such   an   inquire   packet  is  received,  the  node	sends  a
     NGM_CISCO_GET_IPADDR control message to the peer node connected to the inet
     hook (if any).  If the peer responds, then that response is used.	This  is
     the automatic method.

     If  the  peer does not respond, the node falls back on its cached value for
     the IP address and netmask.  This cached value can be set at any time  with
     a NGM_CISCO_SET_IPADDR message, and this is the manual method.

     If  the  inet hook is connected to the inet hook of an ng_iface(4) node, as
     is usually the case, then configuration is automatic as the ng_iface(4) un-
     derstands the NGM_CISCO_GET_IPADDR message.

HOOKS
     This node type supports the following hooks:

     downstream  The connection to the synchronous line.

     inet	 IP hook.

     inet6	 IPv6 hook.

     atalk	 AppleTalk hook.

     ipx	 IPX hook.

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

     NGM_CISCO_SET_IPADDR (setipaddr)
	  This command takes an array of  two  struct  in_addr	arguments.   The
	  first  is the IP address of the corresponding interface and the second
	  is the netmask.

     NGM_CISCO_GET_IPADDR (getipaddr)
	  This command returns the IP configuration in the same format	used  by
	  NGM_CISCO_SET_IPADDR.   This command is also sent by this node type to
	  the inet peer whenever an IP address inquiry packet is received.

     NGM_CISCO_GET_STATUS (getstats)
	  Returns a struct ngciscostat:

	      struct ngciscostat {
		uint32_t   seqRetries;	      /* # unack'd retries */
		uint32_t   keepAlivePeriod;   /* in seconds */
	      };

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

SEE ALSO
     netgraph(4), ng_iface(4), ngctl(8)

     D.  Perkins, Requirements for an Internet Standard Point-to-Point Protocol,
     RFC 1547.

LEGAL
     Cisco is a trademark of Cisco Systems, Inc.

HISTORY
     The ng_cisco node type was implemented in FreeBSD 4.0.

AUTHORS
     Julian Elischer <julian@FreeBSD.org>
     Archie Cobbs <archie@FreeBSD.org>

BUGS
     Not all of the functionality has been implemented.  For example,  the  node
     does not support querying the remote end for its IP address and netmask.

FreeBSD ports 15.quarterly	January 19, 1999		     NG_CISCO(4)

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