Cisco Cisco IOS Software Release 12.2(27)SBC

AToM—Any Transport over MPLS. A protocol that provides a common framework for encapsulating 
and transporting supported Layer 2 traffic types over a Multiprotocol Label Switching (MPLS) network 
core. 

BGP—Border Gateway Protocol. An interdomain routing protocol that replaces Exterior Gateway 
Protocol (EGP). A BGP system exchanges reachability information with other BGP systems. It is 
defined by RFC 1163.

CE router—customer edge router. A router that is part of a customer network and that interfaces to a 
provider edge (PE) router. CE routers do not have routes to associated Virtual Private Networks (VPNs) 
in their routing tables.

core router—In a packet-switched star topology, a router that is part of the backbone and that serves as 
the single pipe through which all traffic from peripheral networks must pass on its way to other 
peripheral networks.

CSC network—Carrier Supporting Carrier network. A network topology in which one service provider 
allows another service provider to use a segment of its backbone network. The service provider that 
provides the segment of the backbone network to the other provider is called the backbone carrier. The 
service provider that uses the segment of the backbone network is called the customer carrier. 

EGP—Exterior Gateway Protocol. Internet protocol for exchanging routing information between 
autonomous systems. It is documented in RFC 904. This term is not to be confused with the general term 
exterior gateway protocol. EGP is an obsolete protocol that was replaced by Border Gateway Protocol 
(BGP).

export packet—(NetFlow) A packet from a device (for example, a router) with NetFlow services 
enabled that is addressed to another device (for example, a NetFlow collector). This other device 
processes the packet (parses, aggregates, and stores information on IP flows). 

FEC—Forwarding Equivalency Class. A set of packets that can be handled equivalently for the purpose 
of forwarding and thus is suitable for binding to a single label. The set of packets destined for an address 
prefix is one example of an FEC. A flow is another example.

flow—A unidirectional set of packets (IP or Multiprotocol Label Switching [MPLS]) that arrive at the 
router on the same subinterface and have the same source and destination IP addresses, the same Layer 4 
protocol, the same TCP/UDP source and destination ports, and the same type of service (ToS) byte in 
the IP header. 

IPv6—IP Version 6. Replacement for the current version of IP (Version 4). IPv6 includes support for 
flow ID in the packet header, which can be used to identify flows. Formerly called IPng (next 
generation). 

label—A short, fixed-length identifier that tells switching nodes how the data (packets or cells) should 
be forwarded.

label imposition—The act of putting a label or labels on a packet.

LDP—Label Distribution Protocol. A standard protocol that operates between Multiprotocol Label 
Switching (MPLS)-enabled routers to negotiate the labels (addresses) used to forward packets. The 
Cisco proprietary version of this protocol is the Tag Distribution Protocol (TDP).

LFIB—Label Forwarding Information Base. A data structure and way of managing forwarding in which 
destinations and incoming labels are associated with outgoing interfaces and labels.

LSR—label switch router. A router that forwards packets in a Multiprotocol Label Switching (MPLS) 
network after looking only at the fixed-length label.