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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.  Typically 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 includes 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)
     understands 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
          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
          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
          Returns a struct ngciscostat:

              struct ngciscostat {
                u_int32_t   seq_retries;       /* # unack’d retries */
                u_int32_t   keepalive_period;  /* 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.