Lucent Technologies PortMaster User Manual
Page 313

Glossary
Glossary-3
autonomous system border router
In OSPF, a router that exchanges information with routers from other autonomous 
systems. Autonomous system border routers are also used to import routing information 
about RIP, direct, or static routes from non-OSPF attached interfaces.
autonomous system path list
In BGP, the list of autonomous systems that a packet must traverse to reach a given set of 
IP address destinations located within a single autonomous system destination. The list 
can consist of sequences, which are series of autonomous systems that must be 
traversed in the order specified, and sets, which are collections of autonomous systems 
one of more of which must be traversed in any order to the destination.
For example, an autonomous system path list might consist of Sequence 1, 2, 3, Set 4, 5, 
Sequence 6, 7. This list indicates that a packet traverses autonomous systems 1, 2, and 3 in 
order, then one or both of autonomous systems 4 and 5 in any order, and finally 
autonomous systems 6 and 7 in order. Autonomous system 7 is the destination 
autonomous system.
B
backbone
A network topology consisting of a single length of cable with multiple network 
connection points.
backbone area
In OSPF, an area consisting of networks and routers not contained in any area and 
autonomous system border routers. The backbone area is responsible for distributing 
routing information between areas. This backbone area must be contiguous either 
physically or through a virtual link. The number reserved for the backbone area is 
0.0.0.0.
backbone router
In OSPF, a router that has an interface into the backbone area by a direct attachment or a 
virtual link.
Basic Rate Interface
See BRI.
