Glossary
GL-2
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
broadband
Characteristic of any network that multiplexes independent network carriers onto a single cable. This
is usually done using frequency division multiplexing (FDM). Broadband technology allows several
networks to co-exist on one single cable; traffic from one network does not interfere with traffic from
another because the “conversations” happen on different frequencies in the “ether” rather like the
commercial radio system.
Broadband Remote
Access Server
Device that terminates remote users at the corporate network or Internet users at the Internet service
provider (ISP) network, that provides firewall, authentication, and routing services for remote users.
broadcast
A packet delivery system where a copy of a given packet is given to all hosts attached to the network.
For example: Ethernet.
C
CAR
Committed access rate.
CBOS
Cisco Broadband Operating System. The common operating system for DSL CPE, including the
Cisco 675, Cisco 675e, Cisco 676, and Cisco 677.
CBR
Constant bit rate. QoS class defined by the ATM Forum for ATM networks. CBR is used for
connections that depend on precise clocking to ensure undistorted delivery.
CBWFQ
Class-based WFQ. Extends the standard WFQ functionality to provide support for user-defined traffic
classes. For CBWFQ, you define traffic classes based on match criteria including protocols, access
control lists (ACLs), and input interfaces. Packets satisfying the match criteria for a class constitute the
traffic for that class. A queue is reserved for each class and traffic belonging to a class is directed to the
queue for that class. On the Cisco 10000 series router, the CBWFQ feature allows a VAI to inherit the
service policy of the VC that the VAI uses.
CEF
Cisco Express Forwarding. An advanced Layer 3 IP switching technology. CEF optimizes network
performance and scalability for networks with large and dynamic traffic patterns such as the Internet,
on networks characterized by intensive Web-based applications, or interactive sessions.
CE router
Customer edge router. A router that is part of a customer network and that interfaces to a provider edge
(PE) router. CE routers are not aware of associated VPNs.
CHAP
Challenge Handshake Authentication Protocol. Security feature supported on lines using PPP
encapsulation that prevents unauthorized access. CHAP does not itself prevent unauthorized access; it
merely identifies the remote end. The router or access server then determines whether that user is
allowed access. Compare to PAP.
CIR
Committed information rate. The reserved bandwidth for the queue. The rate at which a Frame Relay
network agrees to transfer information under normal conditions, averaged over a minimum increment
of time. CIR, measured in bits per second, is one of the key negotiated tariff metrics.
class-based WFQ
See CBWFQ.
