Later adapted to carry IP prefixes in addition to CLNP. (known as Integrated or Dual IS-IS) as described in. RFC ▫ Predominantly used in ISP environment . Unused Features Some features defined in RFC are not in current use. Parker Informational [Page 2] RFC Interoperable IP Networks using IS-IS May. Intermediate System to Intermediate System is a routing protocol designed to move information (IP), the Network Layer protocol of the global Internet. This version of the IS-IS routing protocol was then called Integrated IS-IS (RFC ) .

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From Iisis, the free encyclopedia. ISO standards by standard number. Each IS-IS router independently builds a database of the network’s topology, aggregating the flooded network information.

RFC – Use of OSI IS-IS for routing in TCP/IP and dual environments

As a result, they are conceptually similar. Retrieved May 24, IS-IS routers are designated as being: Both support variable length subnet maskscan use multicast to discover neighboring routers using hello packetsand can support authentication of routing updates.

All articles with unsourced statements Articles with unsourced statements from February Pages using RFC magic links. IS-IS is neutral regarding the type of network addresses for which it can route. Retrieved from ” https: Packets datagrams are then forwarded, based on the computed ideal path, through the network to the destination.


This permits SPB to support large Layer 2 topologies, with fast convergence, and improved use of the mesh topology. IS-IS is a link-state routing protocoloperating by reliably flooding link state information throughout a network of routers.

Supported Standards for IS-IS

SPB allows for shortest-path forwarding in an Ethernet mesh network context rcc multiple equal cost paths. However IS-IS is easier to expand: This article is about a computer network protocol. In addition to that, IS-IS is less “chatty” and can scale to support larger networks. For topics with similar names, see Isis disambiguation.

Routing information is exchanged between Level 1 routers and other Level 1 routers of the same area, and Level 2 routers can only form relationships and exchange information with other Level 2 routers. IS-IS has been called “the de facto standard for large service provider network backbones.

Level 1—2 routers exchange information with both levels and are used to connect the inter area routers with the intra area routers.

Views Read Edit View history. Level 1 intra-area ; Level 2 inter area ; or Level 1—2 both.

It accomplishes this by determining the best route for data through a packet-switched network. IS-IS is an interior gateway protocoldesigned for use within an administrative domain or network. By using this site, you agree to the Terms of Use and Privacy Policy. However, the basic concepts are similar. This map indicates the subnets which each IS-IS router can reach, and the lowest-cost shortest path to a subnet is used to forward traffic. The result is that an IS-IS router is only ever a part of a single area.


International Organization for Standardization.

The complete IS-IS routing protocol. The logical view is that OSPF creates something of a spider web or rgc topology of many areas all attached directly to Area Zero and IS-IS by contrast creates a logical topology of a backbone of Level 2 routers with branches of Level 1—2 and Level 1 routers forming the individual areas.

Intermediate System to Intermediate System IS-ISalso written ISIS is a routing protocol designed to move information efficiently within a computer networka group of physically connected computers or similar devices. 1195

OSPF has a larger set of extensions and optional features specified in the protocol standards. This page was last edited on 28 Novemberat