E

edge router

In MPLS, a router located at the beginning or end of a label-switching tunnel. When at the beginning of a tunnel, an edge router applies labels to new packets entering the tunnel. When at the end of a tunnel, the edge router returns to forwarding the packets using the destination IP address. See also Multiprotocol Label Switching (MPLS).

editor macros (Emacs)

Shortcut keystrokes used within the router’s command-line interface. These macros move the cursor and delete characters based on the specific sequence specified.

egress router

In MPLS, the last router in a label-switched path (LSP). See also ingress router.

electromagnetic interference (EMI)

Any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics or electrical equipment.

Electronic Industries Association (EIA)

A United States trade group that represents manufacturers of electronics devices and sets standards and specifications.

embedded OS software

Software used by a Juniper Networks router to operate the physical router components.

encapsulating security payload (ESP)

A fundamental component of IPSec-compliant VPNs, ESP specifies an IP packet’s encryption, data integrity checks, and sender authentication, which are added as a header to the IP packet. See also Authentication Header (AH).

end system

In IS-IS, the network entity that sends and receives packets.

Equipment Identity Register (EIR)

Mobile network database that contains information about devices using the network.

Established

BGP neighbor state that represents a fully functional BGP peering session.

exact

JUNOS software routing policy match type that represents only the route specified in a route filter.

exception packet

An IP packet not processed by the normal packet flow through the Packet Forwarding Engine. Exception packets include local delivery information, expired TTL packets, or packets with an IP option specified.

Exchange

OSPF adjacency state that means the two neighboring routers are actively sending Database Description packets to each other to exchange their database contents.

Exchange

OSPF adjacency state that means the two neighboring routers are actively sending Database Description packets to each other to exchange their database contents.

Exchange Carriers Standards Association (ECSA)

A standards organization created after the divestiture of the Bell System to represent the interests of interexchange carriers.

explicit path

See signaled path.

Explicit Route Object (ERO)

Extension to RSVP that allows an RSVP Path message to traverse an explicit sequence of routers that is independent of conventional shortest-path IP routing.

Explicit Route Object (ERO)

Extension to RSVP that allows an RSVP Path message to traverse an explicit sequence of routers that is independent of conventional shortest-path IP routing.

export

To place routes from the routing table into a routing protocol.

ExStart

OSPF adjacency state where the neighboring routers negotiate who is in charge of the synchronization process.

Exterior Gateway Protocol (EGP)

The original exterior gateway protocol used to exchange routing information among routers in different Autonomous Systems. EGP was replaced by BGP as the size and complexity of the Internet grew.

External BGP (EBGP)

BGP configuration in which sessions are established between routers in different ASs.

external metric

A cost included in a route when OSPF exports route information from external Autonomous Systems. There are two types of external metrics: Type 1 and Type 2.