Configuring a Synchronous WAN Port        6

This chapter discusses the following topics:

•  "Synchronous Port Uses" on page 6-1

•  "Configuring WAN Port Settings" on page 6-4

  See the Command Line Administrator's Guide for more detailed command descriptions and instructions.

Synchronous Port Uses

All WAN port connections are similar and are represented in Figure 6-1 on page 6-3. For most applications, a dedicated line connects two PortMaster routers, each located on a separate remote network

The following examples describe various uses for synchronous ports.

Routing over Leased Lines. A synchronous port can be used to connect to synchronous leased lines from 9600bps to T1 (1.544Mbps) or E1 (2.048Mbps) for continuous operation. A digital service unit/channel service unit (DSU/CSU) must be attached to the WAN port on the PortMaster. For more information, see Chapter 19, "Using Synchronous Leased Lines."

Routing over Frame Relay. Frame Relay provides connectivity using a packet-switched network. Its two advantages over a leased line network are lower cost and the ability to have multiple permanent virtual circuits (PVCs) come into a single physical port. It is especially popular for hub-and-spoke network arrangements. For example, a dozen field offices with 56Kbps or fractional T1 Frame Relay connections can connect to a central office using a fractional T1 or T1 Frame Relay connection. The central office requires only one CSU/DSU and synchronous port on the router, instead of 12. For more information, see Chapter 13, "Using Frame Relay."

Routing over Switched 56Kbps. Switched 56Kbps can be less expensive than Frame Relay in applications where short bursts of connectivity are required but dial-up modems do not provide enough bandwidth. V.25bis dialing is used to establish a link over a switched network, and the link is brought down after a specified period with no traffic. For more information, see Chapter 14, "Using Synchronous V.25bis Connections."

Routing over ISDN. Integrated Services Digital Network (ISDN) provides fast dial-up connectivity for applications where the expense of a dedicated Frame Relay or leased line connection is not called for by the amount and nature of the traffic. For more information, see Chapter 12, "Using ISDN BRI."

  Figure 6-1 Synchronous WAN Connection Once you have determined the type of synchronous connection to use between your remote locations, the synchronous port on each end of the connection must be configured.

Configuring WAN Port Settings

General Synchronous Settings

Displaying Extended Port Information

To enable or disable extended information for a port, use the following command:

Command> set W1 extended on|off

Note ¯ This command affects only the display of port information. It does not affect port behavior.

Setting the Port Type and Connection Type

To set the port type and the connection type, use the following command:

Command> set W1 network dialin|dialout|twoway|hardwired

Note ¯ Some PortMaster products use S1 through S4 for the synchronous ports. Others use W1, or W0 through W59. Refer to your hardware installation guide for information on port numbering

 Table 6-1 describes the four connection types available on synchronous ports.  

Table 6-1 Port and Network Types

Type	Description
hardwired	Allows you to establish a dedicated network connection between two sites without modem dialing or authentication. In this mode, the port immediately begins running the specified protocol. If the port is set for a hardwired connection, it cannot be used for any other purpose. A hardwired connection must be used for a leased line or Frame Relay connection.
dialin	Allows the port to accept dial-in network connections, for use with switched 56Kbps or ISDN connections. The dial-in user is required to enter a username and password before the connection is established. Authorized users are managed through the user table described in Chapter 7, "Configuring Dial-In Users," or through RADIUS. PPP users wishing to authenticate with PAP or CHAP can start sending PPP packets. When the packets are received, the PortMaster automatically detects PPP and requests PAP or CHAP authentication.
dialout	Allows dial-out to establish connections with remote locations. Dial-out network destinations are managed through the location table described in Chapter 8, "Configuring Dial-Out Connections." This network type can be used for ISDN and switched 56Kbps connections.
twoway	Allows the port to accept dial-in users and use dial-out locations. This network type can be used for ISDN and switched 56Kbps connections.

Setting the Port Speed Reference

To record the port speed, use the following command:

Command> set W1 speed Speed

You can substitute any of the following for Speed:

9600	19200	56000	64000	115200	1536k	t1	e1
14400	38400	57600	76800	1344k	2048k	t1e

Setting Modem Control

Modem control is off for synchronous connections by default. With modem control set off, the PortMaster assumes the carrier detect line is always asserted. Table 6-2 describes the effects of DCD condition on port behavior.  

Table 6-2 Effects of Carrier Detect Condition on Port Behavior

Connection Type	Carrier Detect Asserted	Carrier Detect De-asserted
Hardwired	Port attempts to establish a network connection.	Port is unavailable.
Dialin	PortMaster initiates authentication and displays a login prompt.	Port is unavailable.
Dialout	No effect.	Transition from asserted to de-asserted resets the port.
Twoway	Port attempts to establish a network connection.	Port is available.

Set modem control on only if you want to use the DCD signal from the attached device. In general, set modem control on for network dial-in or dial-out configurations. Modem control is usually off for leased line or Frame Relay connections, but you can use it if the CSU/DSU is configured accordingly.

To set modem control, use the following command:

Command> set W1 cd on|off

Assigning a Port to a Dial Group

To assign a port to a dial group, use the following command:

Command> set W1 group Group

Setting Hangup Control

To set the hangup control, use the following command:

Command> set W1 hangup on|off

The reset command always drops the DTR signal.

Setting the Port Idle Timer

You can set the idle time in seconds or minutes, to any value from 0 to 240. The default setting is 0 minutes. If the value is set to 2 seconds or a longer interval, the port is reset after having no traffic for the designated time. The idle timer is not reset by RIP, keepalive, or SAP packets. To disable the idle timer, set the value to 0.

To set the idle timer, use the following command:

Command> set W1 idle Number [minutes|seconds]

Settings for Hardwired Connections

Setting the Transport Protocol

To set the transport protocol, use the following command:

Command> set W1 protocol ppp|frame

Setting the Port IP Address

You can use any IP address. If you set the local address of the WAN port to 0.0.0.0 for PPP, the PortMaster uses the Ether0 address for the end of the serial link. If you set the WAN port address to 0.0.0.0 for a Frame Relay connection, the port is disabled.

To set the IP address, use the following command:

Command> set W1 address Ipaddress

Setting the Destination IP Address

Do not set a destination IP address for Frame Relay connections. Instead, use the data link connection identifier (DLCI) list to link IP addresses to DLCIs, or use LMI or Annex-D and Inverse ARP to discover Frame Relay addresses dynamically. See Chapter 13, "Using Frame Relay," for more information.

For network dial-in or dial-out connections, do not set a destination IP address for the port. Instead, you set the destination address in the user table or RADIUS for dial-in, or in the location table for dial-out. See Chapter 7, "Configuring Dial-In Users," and Chapter 8, "Configuring Dial-Out Connections," for more information.

To set the destination IP address for a leased-line connection only, use the following command:

Command> set W1 destination Ipaddress [Ipmask]

Setting the Subnet Mask

To set the subnet mask, use the following command:

Command> set W1 netmask Ipmask

See Appendix A, "Networking Concepts," for more information about using subnet masks.

Setting the IPX Network Address

Note ¯ The serial link itself must have an IPX network number that is different from those at either end of the connection.

To set the IPX network address, use the following command:

Command> set W1 ipxnet Ipxnetwork

Configuring RIP Routing

Turn on RIP routing for the port for network hardwired connections only such as leased lines or Frame Relay. Routing is set in the user table for dial-in connections and in the location table for dial-out connections.

To configure RIP routing, use the following command:

Command> set W1 rip on|broadcast|listen|off

Note ¯ ComOS releases prior to 3.5 used the keyword routing instead of the rip keyword.

 Table 6-3Table 6-3 describes the results of using each keyword.  

Keywords for Configuring RIP Routing

Keyword	Description
on	The PortMaster broadcasts and accepts RIP packets from the system at the other end of the WAN connection. This is the default.
off	The PortMaster neither broadcasts nor listens for RIP information on the interface.
broadcast	The PortMaster broadcasts RIP packets to the system at the other end of the WAN connection.
listen	The PortMaster accepts RIP packets from the device connected to the WAN port.

See the PortMaster Routing Guide for instructions on configuring OSPF routing or configuring BGP routing.

Setting Input and Output Filters

Note ¯ You must define a filter in the filter table before you can apply it. For more information about filters, see Chapter 9, "Configuring Filters."

To apply an input filter to a synchronous port, use the following command:

Command> set W1 ifilter [Filtername]

To apply an output filter to a synchronous port, use the following command:

Command> set W1 ofilter [Filtername]

You can remove filters from the port by entering the command without a filter name. If a filter is changed, you must reset the port for the change to take effect.

For example, to remove the output filter from a synchronous port, use the following commands:

Command> set W1 ofilter Command> reset W1 Command> save all

Note ¯ You must reset the port and re-establish the connection for the new settings to take effect.

Compression