---
name: "ng_cisco"
section: "4"
platform: "linux"
package: "freebsd-manpages"
version: "6.0-5"
release: "Debian 4.0 (Etch)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/ng_cisco"
---

# ng\_cisco(4)

Cisco HDLC protocol netgraph node type

## 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)](/ng_iface/4.md) 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)](/ng_iface/4.md) node, as is usually the case, then configuration is automatic as the [ng\_iface(4)](/ng_iface/4.md) 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)](/netgraph/4.md), [ng\_iface(4)](/ng_iface/4.md), [ngctl(8)](/ngctl/8.md) 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.