 - One of the most commonly used routing protocols, the Intermediate System-to-Intermediate System protocol (IS-IS) is based on a routing method known as DECnet Phase V routing, in which routers known as intermediate systems exchange data about routing using a single metric to determine the network topology. IS-IS was developed by the International Organization for Standardization (ISO) as part of their Open Systems Interconnection (OSI) model. The first versions of IS-IS were used to manage routing within ISO Connectionless Network Protocol (CLNP) networks. IS-IS was ratified as a standard in 1990 (OSI IS-IS Intra-domain Routing Protocol, IETFRFC 1142 [2], ISO/IEC 10589 [3]).
In the OSI context, an intermediate system refers to a router, as opposed to an end system (ES), which refers to a node. ES-IS protocols allow routers and nodes to identify each other; IS-IS performs the same service between nodes for routing purposes. In common with other routing protocols such as OSPF (Open Shortest Path First), IS-IS is a link state protocol: it stores information about the state of links and uses that data to select paths. IS-IS is used to intermittently send out link state information across the network, so that each router can maintain a current picture of network topology. Optional metrics can be used to identify network delay, expense, and error involved with the use of a particular link.
| CONTRIBUTORS: |
Mike Ward |
| LAST UPDATED: |
25 Jun 2007
|
 |
Read more about IS-IS:
|
|
Do you have something to add to this definition? Let us know.
Send your comments to techterms@whatis.com
|
 |
 |
| |
RELATED GLOSSARY TERMS
| Terms from Whatis.com − the technology online dictionary |
 |
32-bit IP addressing
(SearchNetworking.com)
32-bit IP addressing is the IP address scheme used in Internet Protocol 4 (IPv6 uses a 128-bit system)... (Continued)
|
|
autotrunking
(SearchNetworking.com)
Autotrunking is a function that can be activated for one or more switch ports in a Cisco system of virtual local area networks (VLANs), making those...
|
|
|
