Network Glossary N

NA See Neighbor Advertisement.

NAT See Network Address Translation.

NAT-PT See Network Address Translation-Protocol Translation.

native VLAN The one VLAN on an 802.1Q trunk for which the endpoints do not add the 4-byte 802.1Q tag when transmitting frames in that VLAN.

NBAR See Network Based Application Recognition.

NCP See Network Control Protocol.

ND See Neighbor Discovery Protocol.

neighbor (EIGRP) With EIGRP, a router sharing the same primary subnet, with which Hellos are exchanged, parameters match, and with which routes can be exchanged.

neighbor (OSPF) Any other router, sharing a common data link, with which a router exchanges Hellos, and for which the parameters in the Hello pass the parameter-check process.

Neighbor Advertisement In IPv6, the Neighbor Discovery message used by an IPv6 node to send information about itself to its neighbors.

Neighbor Discovery Protocol The protocol used in IPv6 for many functions, including address autoconfiguration, duplicate address detection, router, neighbor, and prefix discovery, neighbor address resolution, and parameter discovery.

Neighbor Solicitation In IPv6, the Neighbor Discovery message used by an IPv6 node to request information about a neighbor or neighbors.

neighbor state A state variable kept by a router for each known neighbor or potential neighbor.

Neighbor Type In BGP, either external BGP (eBGP), confederation eBGP, or internal BGP(iBGP). The term refers to a peer connection, and whether the peers are in different ASs(eBGP), different confederation sub-ASs (confederation eBGP), or in the same AS (iBGP).

nested policy maps An MQC configuration style by which one policy map calls a second policy map. For example, a shaping policy map can call an LLQ policy map to implement LLQ for packets shaped by CB Shaping.

Network Address Translation Defined in RFC 1631, a method of translating IP addresses in headers with the goal of allowing multiple hosts to share single public IP addresses, thereby reducing IPv4 public address depletion.

Network Address Translation-Protocol Translation As defined in RFCs 2765 and 2766, a method of translating between IPv4 and IPv6 that removes the need for hosts to run dual protocol stacks. NAT-PT is an alternative to tunneling IPv6 over an IPv4 network, or vice versa.

network allocation vector A time value that each wireless station must set based on the duration value found in every 802.11 frame. The time value counts down and must be equal to zero before a station is allowed to access the wireless medium. The result is a collision-avoidance mechanism.

Network Based Application Recognition A Cisco IOS feature that performs deep packet inspection to classify packets based on application layer information.

Network Control Protocol The portions of PPP focused on features that are related to specific Layer 3 protocols.

network layer reachability information A BGP term referring to an IP prefix and prefix length.

Network Time Protocol An Internet standard (RFC 1305) that defines the messages and modes used for IP hosts to synchronize their time-of-day clocks.

network type (OSPF) A characteristic of OSPF interfaces that determines whether a DR election is attempted, whether or not neighbors must be statically configured, and the default Hello and Dead timer settings.

Next Hop field With a routing update, or routing table entry, the portion of a route that defines the next router to which a packet should be sent to reach the destination subnet. With routing protocols, the Next Hop field may define a router other than the router sending the routing update.

NEXT_HOP A BGP path attribute that lists the next-hop IP address used to reach an NLRI.

NLPID Network Layer Protocol ID is a field in the RFC 2427 header that is used as a Protocol Type field in order to identify the type of Layer 3 packet encapsulated inside a Frame Relay frame.

NLRI See network layer reachability information.

no drop A WRED process by which WRED does not discard packets during times in which a queue’s minimum threshold has not been passed.

NO_ADVERT A reserved value for the BGP COMMUNITY path attribute that implies that the route should not be advertised to any other peer.

NO_EXPORT A reserved value for the BGP COMMUNITY path attribute that implies that the route should not be advertised outside the local AS.

NO_EXPORT_SUBCONFED The RFC 1997 name for the reserved COMMUNITY path attribute known to Cisco IOS as LOCAL_AS. (See LOCAL_AS.)

not-so-stubby area A type of OSPF stub area that, unlike stub areas, can inject external routes into the NSSA area.

NS See Neighbor Solicitation.

NSSA See not-so-stubby area.

NTP See Network Time Protocol.

NTP broadcast client An NTP client that assumes that a server will send NTP broadcasts, removing the requirement for the client to have the NTP server’s IP address preconfigured.

NTP client mode An NTP mode in which an NTP host adjusts its clock in relation to an NTP server’s clock.

NTP server mode An NTP mode in which an NTP host does not adjust its clock, but in which it sends NTP messages to clients so that the clients can update their clocks based on the server’s clock.

NTP symmetric active mode An NTP mode in which two or more NTP servers mutually synchronize their clocks.