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Chapter 12. Configuring Interfaces

Ethernet is certainly a popular choice these days, but you can send traffic through other physical media. This chapter is about those other guys, the physical interfaces that have taken a back seat to Ethernet but are still very much needed in your network. In this chapter, you find out what you need to know about T1, DS1, DS3, and serial interfaces. You also discover how to configure DSL interfaces. Our goal is to leverage your existing interface knowledge to round out your router and establish connectivity with your branch office.

Types of Physical Interfaces

Ethernet is by far the most popular interface, but it's anything but the only game in town. Several other types of physical interfaces are used in various networks. Because we focus on those interfaces that most commonly appear in enterprise branch offices, the larger interfaces (such as SONET interfaces) are beyond the scope of this particular chapter.

The primary interfaces that are applicable include

• T1 and DS1 interfaces

• Serial interfaces

• Digital subscriber line (DSL) interfaces

T1 interfaces

When people talk about T1 interfaces and DS1 interfaces, they're really talking about the same thing. T1 is basically a digital data transmission medium that can handle traffic at speeds of 1.544 Mbps.

You may also hear people mention E1 interfaces. E1 interfaces are the European equivalents to T1 interfaces, which are more common in North America. E1 interfaces are actually a bit faster, clocking in at ...