Slowly moving these entries into the new glossary format! Don’t mind this page!

IEEE 802.1QAn IEEE industry standard Trunking protocol. Commonly referred to as ‘dot 1 q’.
LAN(Local Area Network); A collection of devices/nodes in one geographic location. Particularly end-hosts and Layer-2 devices; everything in a network up to, but not including, Internet Protocol
MulticastMulticast messages are delivered to devices that have joined a specific multicast group. Compare to Broadcast and Unicast.
Multilayer SwitchAlso called a ‘Layer 3 Switch’. A switch which can operate at Layer 3, similar to a router. This is useful for routing traffic between multiple VLANs without a separate router. Forwarding traffic at Layer 3 is also handy as it mitigates the need for STP as routed ports do not forward Layer 2 broadcasts. See Switches.
Network RouteAn IP route to a network or subnet. I.e. a route with a netmask of less than /32
OSI Model(Open Systems Interconnection); A 7-layer model for computer networking. While it is not actually implemented (the real model used today is IP) it is useful for learning/discussing the concepts of networking. When people refer to ‘Layer x’ they are referring to a layer of the OSI Model.
OSPF(Open Shortest Path First); A Link-State based Interior Gateway Dynamic Routing Protocol
OversubscriptionWhen the bandwidth of the interfaces connected to end hosts is greather than the bandwidth of the connection to the distribution switch(es). Some is generally acceptable, assuming not all hosts are sending/receiving data at all times, but too much will cause congestion. See EtherChannel.
PAgP(Link Aggregation Protocol); A Cisco-proprietary EtherChannel protocol. Dynamically negotiates the creation & maintenance of an EtherChannel. Roughly equivalent to LACP (IEEE 802.3ad). See EtherChannel.
RIP(Routing Information Protocol); A Distance-Vector based Interior Gateway Dynamic Routing Protocol
Routing-by-RumorWhen routers in a network have no understanding of the network at large, and must forward traffic using routes they are advertised by adjacent routers. See Dynamic Routing
[[STP#Rapid STP\RSTP]](Rapid Spanning Tree Protocol); Serves the same purpose as STP but operates much more quickly by replacing STP’s timers with a negotiation algorithm.
STP(Spanning Tree Protocol); Prevents Layer 2 Loops (and thereby broadcast storms) by setting some ports in a LAN to a blocking state, effectively creating only one possible path between any two nodes on the network.
TCP(Transmission Control Protocol);
IPThe Internet Protocol Suite; A framework for organizing the set of communication protocols used in the internet and similar computer networks, according to functional criteria.
TrunkA connection between two switches which can carry traffic from multiple VLANs
UnicastUnicast messages are delivered to a single, specific network destination. Compare to Broadcast and Multicast.
WAN(Wide Area Network);
Wildcard MaskAn alternative way of depicting a subnet mask. Basically an ‘inverted’ subnet mask i.e. all 1s in the subnet mask are 0s in the wildcard mask and vice-versa. See Netmasking

Ex.: (Subnet Mask) 11111111.11111111.11111111.00000000 = (Wildcard Mask) 00000000.00000000.00000000.11111111= /24
Netmask/Subnet Mask
Router ID (RID)Used to identify a router, commonly by Dynamic Routing protocols. Can be manually configured, or selected procedurally as the highest IP of a loopback interface (preferred) or the highest IP of a physical interface (fallback). See Dynamic Routing
LSA(Link State Advertisement); Used by OSPF routers to advertise connected networks to other routers in the OSPF Area. See OSPF
LSDB(Link State Database); Used by OSPF routers to store all routes they have received as LSAs. Effectively stores a ‘connectivity map’ of the entire OSPF Area. LSDBs are identical between all routers in an OSPF Area
Area (OSPF)A set of routers and links that share the same Link State Databse (LSDB)
Backbone AreaThe first OSPF Area in a network which all other areas must be connected to. See OSPF
Internal RouterA router with all its interfaces in a single OSPF area. See OSPF
Area Border Router (ABR)Routers with interfaces in multiple OSPF areas. See OSPF
Backbone RouterA router connected to the OSPF backbone area. See OSPF
Autonomous System Boundary Router (ASBR)A router that connects an OSPF network to networks outside the OSPF domain.