User`s guide

16 XSR User’s Guide
Utilizing the Command Line Interface Chapter 2
Managing the XSR
Describing Ports and Interfaces
This section describes ports and interfaces, the rules for port identification,
and the association of port with interface.
Technically speaking, a port is a physical connector with some physical layer
values. XSR ports are: FastEthernet or GigabitEthernet, async and sync serial,
and T1/E1. An interface is a data and management plane comprising the
physical, link, and some part of the network layer. The terms are often used
interchangeably in this manual. FastEthernet ports are provided on the
XSR 1800 Series, and GigabitEthernet ports on the XSR 3000 Series routers.
The XSR supports multiple access types, including FastEthernet/ GigabitEthernet
LAN, Frame Relay and serial WAN access over Asynchronous, Synchronous,
T1/E1, and serial lines. Async and Sync access can be over permanent or dial lines.
Generally, Frame Relay and PPP are used for WAN access and PPPoE for WAN
access over a LAN. Dial access is provided by ISDN BRI and PRI.
Supported Physical Interfaces
 FastEthernet/GigabitEthernet for LAN port consisting of Ethernet's
physical, Mac (Layer-2), and IP layer functionality.
 Serial for Sync port/line consisting of a Sync port/line's physical,
Layer-2 (PPP) and IP layer functionality.
 Serial for Async port/line consisting of an Async port/line's physical,
Layer-2 (PPP), and IP layer functionality.
 Serial for T1/E1 channel group consisting of its physical, Layer-2 (PPP
or Frame Relay), and IP layer functionality.
Supported Virtual Interfaces
 Interface dialer includes physical interfaces supporting dial
connectivity from the dial port/line's physical layer functionality
including dialing, Layer-2 (PPP), and IP layer functionality.
 Sub-Interface for an NBMA network. An NBMA network has multiple
access over the same line but no broadcast capability. Examples of such
networks are Frame Relay, X.25, and ATM. One physical interface
comprises one or more sub-interfaces which in turn consist of one or
more circuits on the physical interface. Sub-interface examples and its
circuits are: one or more DLCIs forming a sub-interface, one or more