Serial Interface Configuration

This section presents the following topics:

•Virtual Interfaces on Serial Interfaces

•Enabling Interfaces

•Viewing Available Serial Interfaces

Virtual Interfaces on Serial Interfaces

The Vyatta system distinguishes between physical interfaces (interfaces), and logical interfaces (virtual interfaces, or vifs).

Every physical network device in the system is considered to be an “interface.” An example of a interface is a physical port on a serial card. Every serial interface has zero or more corresponding vifs.

On serial interfaces, physical line characteristics are specific for the interface, but encapsulation (Cisco HDLC, Frame Relay, or Point-to-Point Protocol) is specified for vifs.

Unlike Ethernet interfaces, a physical serial interface cannot directly have a configured IP address. Instead, the IP address must be assigned to the vif.

Note that each serial vif can support exactly one IP address.

Enabling Interfaces

The Vyatta system will automatically discover any available physical serial interfaces on startup. Before you can apply any configuration to a serial interface, a vif must be “created” for the interface and its encapsulation specified in the configuration tree.

For serial interfaces, physical line characteristics are applied to the interface as a whole. Encapsulation characteristics are applied to the vif, as shown in the configuration hierarchy below:

interfaces { serial wan0 {

ppp {

vif 1 {

}

}

}

}

The current implementation supports Cisco HDLC, Frame Relay, and Point-to-Point Protocol encapsulation.

•Cisco HDLC and point-to-point interfaces support only one vif, and this vif must have the identifier 1.

•The identifier for Frame Relay vifs is the DLCI number. This can range from 16 through 991.

•Currently, any vif on a serial interface can support exactly one IP address.

Viewing Available Serial Interfaces

You can only configure interfaces that actually are available to the operating system on the hardware you are using.

To view all the interfaces known to the operating system, use the show interfaces system command in operational mode, as shown in Example 1-1:

Example 1 1 Viewing available system interfaces

vyatta@vyatta> show interfaces system

eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:15:c5:fb:ba:e9 brd ff:ff:ff:ff:ff:ff inet6 fe80::215:c5ff:fefb:bae9/64 scope link

lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo