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-encapsula

tion 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 proto

col. 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 be

cause the protocol includes an ``inquire'' packet which we must be prepared

to answer.
There are two ways to accomplish this, manually and automat

ically.

Whenever such an inquire packet is received, the node sends

a
NGM_CISCO_GET_IPADDR control message to the peer node con

nected to the
inet hook (if any). If the peer responds, then that re

sponse 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 argu

ments. 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 re

tries */
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 ex

ample, the node
does not support querying the remote end for its IP address

and netmask.

BSD January 19, 1999

BSD