B-18
Appendix B: Glossary
Gbps, up to 200 billion bits can be delivered per second by the optical fiber.
DWDM is also sometimes called Wave Division Multiplexing (WDM). For
information about IP over optical networks, see RFC 3717 (at http://
www.ietf.org/rfc/rfc3717.txt).
E
E0 The base bandwidth multiple of E-carrier systems. E0 channels can transmit
at up to 64 Kbps.
E1-carrier line Provides a dedicated WAN connection. This multiplexed carrier-line includes
32 E0 channels for a total bandwidth of 2.048 Mbps. E-1 carrier lines are
offered in Europe, Asia, Australia, and South America. (In Japan, PTTs offer
J-carrier lines for voice and T1- or E1-carrier lines for data.) See also PTT.
E1 frame format A frame format used for E1-carrier lines. In the E1 frame format, a channel
(or timeslot) is called a TS, and the 32 channels are numbered TS0 to TS31.
Two channels are used to establish and maintain synchronization and signal-
ing: Specifically, TS0 is used for synchronization, error detection, and alarms,
and TS16 is used for signaling. The other channels are used to transmit data
E3-carrier line A carrier line that includes 512 E0 channels (or 16 E1 channels) for a total
transmission rate of 34.368 Mbps.
EAP Extensible Authentication Protocol. A protocol that allows PPP to use authen-
tication protocols that are not part of the PPP suite. For more information
about EAP, see RFC 3748 (at http://www.ietf.org/rfc/rfc3748.txt). See also
CHAP, PAP, and PPP.
eBGP External Border Gateway Protocol. A BGP routing protocol that allows exter-
nal route broadcasting to routers in other Autonomous Systems. See also BGP.
Echo Cancellation In digital voice transmissions over packet-based networks, echo cancellation
is a technique that filters unwanted signals called “echoes.” Echoes are usually
generated by background noise or hybrid/acoustic noise.
ECP Encryption Control Protocol. An NCP in the PPP suite that allows you to
configure options for encrypting PPP datagrams. ECP is responsible for
negotiating and managing the use of encryption on a PPP link. For more
information about ECP, see RFC 1968 (at http://www.ietf.org/rfc/rfc1968.txt).
See also NCP and PPP.
EGP Exterior Gateway Protocol. The first exterior LAN routing protocol used on
the Internet. EGP’s basic functions are to identify neighbors and share reach-
ability information, poll neighbors to determine if they’re still available, and
advertise system information. Because EGP cannot determine the best route
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