This glossary is intended as a quick reference for terms you may be unfamiliar with. More complete descriptions of the most entries can be found by consulting the index.

3G

Shorthand for Third Generation mobile services.

3GPP

3rd Generation Partnership Project, a group set up to work on standards for third generation mobile telecommunications.

6bone

The original test network for IPv6 consisting of sites joined by tunnels. The 6bone is now beginning its retirement, due for completion by 06/06/2006.

ACL

An Access Control List is a way of specifying who can access a particular file, network or service. Different vendors and different software all have their own way to specify ACLs.

anycast

A way of sending a packet so that it is destined to any one of a group of machines. Compare this with multicast.

API

An Application Programming Interface is a standard set of data structures, functions and methods made available to programmer to allow access to some facility, such as a network protocol or a windowing interface.

APNIC

The Asia Pacific Network Information Centre is the RIR for the part of the world you’d guess it would be.

ARIN

The American Registry for Internet Numbers is the RIR for North America and some other countries in the Caribbean and Africa.

ARP

The Address Resolution Protocol, used by IPv4 to translate IPv4 addresses into lower layer addresses, such as Ethernet MAC addresses.

AS

Autonomous Systems are routing black boxes out of which a BGP network is built. Within an AS, routing will be managed by an IGP, between ASs routing is managed by BGP.

ATM

Asynchronous Transfer Mode, a layer 2 technology that moves small chunks of data called cells around a network.

bit

A bit is the basic unit of data storage on most computers. It can remember if something had value 0 or 1. Bits are combined together to remember more complicated things such as address, words and images.

BOF

Birds of a Feather, a group of people, usually at a conference, meeting to discuss a particular common interest.

BGP

A protocol for connecting networks together in a fashion resistant to failure.

broadcast

A broadcast packet is one that is delivered to all machines on a network.

CIDR

Classless Interdomain Routing, a way of splitting IPv4 addresses into a network part and a host part without using the Class A, B and C system.

CIFS

Common Internet Filesharing System. A Microsoft protocol for sharing files; also known as SMB.

CLNP

The ConnectionLess Network Protocol, part of the ISO protocol stack, specified in ISO 8473.

CPE

Customer Premises Equipment. In other words, the kit that ends up on-site, at the customer premises.

DAD

Duplicate Address Detection, a process IPv6 nodes conduct to make sure an address is unused before they use it.

default free zone

The part of the Internet that does not have a `default route’ and so it has to calculate a route to every network on the Internet, using a combination of an EGP and a IGP.

deprecate

To deprecate something is to pension it off and, with a slightly disapproving tone, mark it as no longer suitable for general use. This happens to addresses in IPv6, old facets of protocols in the IETF, and sometimes even entire operating systems. Of course, many people wonder if we will be able to deprecate IPv4 some day.

DHCP

DHCP is the dynamic host configuration protocol. It is used to allow an IPv4 host find its IP address and other information, such as the local name server, without having to store this information locally.

discontiguous

Things are discontiguous if they are not adjacent, or immediate neighbors.

DNS

The Domain Name Service, a distributed database translating between hostnames and addresses. Other information can also be stored in the DNS, such as mail routing information or telephone numbers.

DoS

Denial of Service; usually means a type of malicious network traffic that is sent with the intention of removing access to a network, a machine or individual, often using overwhelming amounts of traffic.

dual stack

A dual-stacked node is one that has a working IPv4 and IPv6 stack. While both IPv4 and IPv6 are in use, dual-stacked routers and proxies will form an important part of keeping the Internet operating smoothly for everyone. Since TCP and UDP are more-or-less the same in IPv4 and IPv6, some vendors actually produce only dual IP level stacks and use a common stack above that.

EGP

An Exterior Gateway Protocol is a protocol, such as BGP, that is spoken between routers in different networks to establish a routing table. At one time there was an EGP called EGP.

flag day

A flag day is a time when everyone has to coordinate to make some change. For example, if everyone had to shut down their computer one day, uninstall IPv4 and install IPv6, that would be a flag day. Naturally, a design aim of the IPv6 deployment process is to avoid flag days.

GPRS

General Packet Radio Service, a way to use 2^nd generation mobile phone networks for packet data. GPRS is considered to be 2.5G.

jitter

Varying amounts of latency. If a TCP connection is suffering from serious jitter, performance is very difficult to predict, and it generally causes users to be annoyed and/or confused. On the other hand, if the latency is large but constant, performance is predictable and generally more manageable for users.

IANA

The Internet Assigned Numbers Authority, the traditional body associated with standardizing IP addresses, protocol numbers, port numbers and the like. These responsibilities now largely fall with ICANN.

ICANN

Internet Corporation for Assigned Names and Numbers, in their own words, is a global, consensus-driven, non-profit organization formed to assume responsibility for the IP address space allocation, protocol parameter assignment, domain name system management, and root server system management.

ICMP

The Internet Control Message Protocol, used to communicate errors and other diagnostic messages across within IP. An expanded and revised version of ICMP is included in IPv6.

IETF

The Internet Engineering Taskforce. The people who write RFCs and Internet-Drafts in an effort to make the Internet interoperable, comprehensible and manageable.

IGP

An Interior Gateway Protocol is spoken between routers in a network to learn about routes within that network. IS-IS and OSPF are IGPs. Compare to EGP.

IKE

Internet Key Exchange is a protocol for establishing keys and algorithms to be used by IPsec.

IMAP

The Internet Message Access Protocol is like POP on steroids.

IMS

Internet Multimedia Subsystem. A complicated way of saying “server farm” in 3G networks.

Internet-Draft

These are the working documents of the IETF that may, in time, become RFCs.

IPsec

A technique for providing privacy, authentication and other security related services at the IP level.

IPv4

The version of the Internet Protocol mainly in use within the Internet.

IPv6

A new version of the Internet Protocol, designed to address issues that have arisen with IPv4.

IS-IS

IS-IS is a routing protocol from the OSI protocol suite. It routes from Intermediate System to Intermediate System. It is sometimes used in the IP world as an IGP.

ISP

Internet Service Providers are people who are in the business of providing others with a connection to the Internet.

KAME

A group, based in Japan, working to provide IPv6 and IPsec for the BSD family of operating systems. They have also provided patches to make well-known software IPv6 capable.

LACNIC

The Latin American and Caribbean Internet Addresses Registry is the RIR for, well, Latin American and the Caribbean. It is a young RIR and was fully recognized in 2002.

LIR

A Local Internet Registry. Like an RIR, but operating on a organizational level within a country, rather than a continent wide level.

machine

Another name for a computer, as in `reboot that machine’ or `have you finished installing those Solaris machines’.

MLD

Multicast listener discovery is a part of ICMPv6 that allows a router to find out what multicast addresses are being listened for on a link.

MPLS

Multipath labelled switching is a technique for routing packets quickly through a network based on labels that are assigned when the packet enters the network. Has a chewy ATM flavour.

MTU

Maximum Transmission Unit, the size of the largest packet that can be transmitted on a link.

multicast

A way of sending a packet to a certain group of machines. Multicast can be much more efficient than broadcast.

multihoming

A network with multiple connections to the Internet, usually for reasons of improved reliability, is described as multihomed. An analogy is an ISP is your home network within the Internet, and if you have multiple ISPs then you have multiple homes.

NAT

Network Address Translation, a technique for rewriting the addresses on packets as they enter and leave a network. Usually used to allow many hosts to use a single public IPv4 address.

ND

Neighbor Discovery, the broad equivalent of ARP in IPv6.

NNTP

The Net News Transfer Protocol, used for transporting Usenet News around the Internet.

NTP

The Network Time Protocol is a fiendishly clever system for keeping clocks in sync using the Internet.

OSI

A family of protocols once considered to be in competition with IP. It is now best known for the layered paradigm used in its design.

OSPF

Open Shortest Path First is an IP routing protocol used within a organization, making it an example of an IGP. OSPF has been updated to support IPv6.

PA

Provider Aggregate is a term used to describe addresses assigned to someone that are a subset of the addresses assigned to their network provider. cf. PI

P2P

Person to Person or Peer to Peer. A method of filesharing or communicating that is not centralized.

PI

Provider Independent addresses are addresses assigned directly to an organization, rather than borrowing addresses from their network provider. cf. PA

PIM

Protocol Independent Multicast is a protocol for routing multicast traffic. It comes in two flavours, sparse and dense.

POP

The Post Office Protocol is used to allow users to collect their mail from a mail server.

PPP

The point-to-point protocol is for transporting packets from a variety of protocols over a point-to-point link. It was most commonly used for traditional dialup Internet services, but has variants such as PPPoE (PPP over Ethernet) and PPPoA (PPP over ATM) have become more common as DSL has become available to more people.

prefix

A prefix is a block of IPv4 or IPv6 addresses determined by fixing the first n bits of the address. For example, 192.168.8.0/24 is the collection of IPv4 addresses that look like 192.168.8.anything. Similarly, 2000::/3 is the collection of IPv6 address that start with the digit 2 or 3.

QoS

Quality of Service—the ability to ensure that network traffic ends up where it is supposed to, when it is supposed to be, and within the right amount of the time.

RFC

The standards documents for the Internet, produced by the IETF. RFC stands for Request For Comments.

RIP

The Routing Information Protocol is one of the simplest IP routing protocols. RIPng is a version of RIP running over IPv6.

RIPE

Réseaux IP Européens, the European Regional Internet Registry, for some definition of Europe.

RIR

Regional Internet Registries work to allocate resources needed for the operation of the Internet, such as addresses. They also usually provide support to those administering Internet infrastructure and help with the development of standards and policies.

SIP

The Session Initiation Protocol is a standard for initiating multi-media conversations between various kinds of endpoints (such as 3G phones, desktop PCs, laptops, etc.).

SMB

Server Message Block, a Microsoft protocol for sharing files also known as CIFS.

SMTP

The Simple Mail Transfer Protocol is used to get email from A to B in the Internet.

ToS

Type of Service—several bits in an IPv4 packet used to identify service requirements of the that packet. The Traffic Class field serves a similar function in IPv6.

transit

A network on the Internet provides transit if it carries traffic that neither originates nor terminates locally. This is usually thought of in terms of BGP Autonomous Systems, so an AS provides transit if traffic flows through that AS that is neither to nor from that AS. For example, a small ISP that carries traffic only for their own customers is not a transit network, but a large ISP that carries traffic for multiple smaller networks and between other large ISPs is a transit network.

TSIG

Transaction SIGnature. A particular way of signing a DNS transaction so that you can have more confidence it’s correct.

tunnel

Tunnelling is a way of getting packets from one point in a network to another without the intermediate networking understanding those packets. This usually involves wrapping extra headers around the packets that the intermediate network does understand. The most common example in the IPv6 arena is wrapping IPv6 packets in IPv4 so that they can traverse the IPv4 Internet.

tunnel broker

A tunnel broker is someone who can provide you a IPv4 address that you can tunnel IPv6 packets to. They will usually provide you with IPv6 addresses for your end of the tunnel too.

UMTS

Universal Mobile Telephony Service. A third generation mobile standard.

Unicast

The usual way packets are sent, where they only have a single destination. Other options include anycast, broadcast and multicast.

userland

The part of an operating system outside its kernel or core. This includes all the tools typically run by the user.

USAGI

USAGI is a project to provide IPv6 and IPsec support for Linux.

VLAN

Virtual LAN, a method of defining one or more logical networks within a single physical Ethernet. They are usually used to keep particular machines on separate networks while sharing the same switching infrastructure.