Cisco CCNA Study Guide - Router Alley

CCNA Study Guide v2.62 – Aaron Balchunas
139
Interfaces vs Lines
Cisco devices contain two distinctly different types of ports, interfaces and
lines.
Interfaces connect routers and switches to each other. In other words, traffic
is actually routed or switched across interfaces. Examples of interfaces
include (but are not limited to):
• Serial interfaces
• Ethernet interfaces
• Fast Ethernet interfaces
• Token Ring interfaces
• ATM interfaces
Interfaces are identified by both the type of interface, and the interface
number (which always begins at “0”). Thus, the first Ethernet interface on a
router would be identified as Ethernet0.
Certain router families (such as the 3600 series) are modular, and have
multiple “slots” for interfaces. Thus, interfaces on these routers are
identified by both the module number and the interface number, formatted
as: module/interface. Thus, the third Fast Ethernet interface on the first
modular slot would be identified as FastEthernet0/2.
Lines identify ports that allow us to connect into, and then configure, Cisco
devices. The most common examples of lines include:
• Console ports
• Auxiliary ports
• VTY (telnet) ports
Just like interfaces, lines are identified by both the type of line, and the line
number (again, always begins at “0”). Thus, the first console port on a router
would be identified as Console0.
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