table of contents
NG_CISCO(4) | Device Drivers Manual | NG_CISCO(4) |
NAME¶
ng_cisco — Cisco HDLC protocol netgraph node typeSYNOPSIS¶
#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. Thedownstream
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 aNGM_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 theinet
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 aNGM_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.January 19, 1999 | Debian |