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IS-IS was developed at roughly the same time that the Internet Engineering Task Force IETF was developing a similar protocol called OSPF.
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IS-IS and was
The IS-IS protocol was developed by Digital Equipment Corporation as part of DECnet Phase V. It was standardized by the ISO in 1992 as ISO 10589 for communication between network devices which are termed Intermediate Systems ( as opposed to end systems or hosts ) by the ISO.
The purpose of IS-IS was to make possible the routing of datagrams using the ISO-developed OSI protocol stack called CLNS.
IS-IS was later extended to support routing of < em > datagrams </ em > in the Internet Protocol ( IP ), the Network Layer protocol of the global Internet.
This version of the IS-IS < em > routing </ em > protocol was then called < em > Integrated IS-IS </ em > ( RFC 1195 ).
The technique was later adapted for use in the contemporary link-state routing protocols IS-IS and OSPF.
IS-IS and at
While OSPF is natively built to route IP and is itself a Layer 3 protocol that runs on top of IP, IS-IS is natively an OSI network layer protocol ( it is at the same layer as CLNS ).
In OSPF, areas are delineated on the interface such that an area border router ( ABR ) is actually in two or more areas at once, effectively creating the borders between areas inside the ABR, whereas in IS-IS area borders are in between routers, designated as Level 2 or Level 1-2.
IS-IS and same
PNNI uses the same shortest-path-first algorithm used by OSPF and IS-IS to route IP packets to share topology information between switches and select a route through a network.
Both IS-IS and OSPF are link state protocols, and both use the same Dijkstra algorithm for computing the best path through the network.
Given the same set of resources, IS-IS can support more routers in an area than OSPF.
IS-IS and time
In most current networking environments, RIP is not the preferred choice for routing as its time to converge and scalability are poor compared to EIGRP, OSPF, or IS-IS ( the latter two being link-state routing protocols ), and ( without RMTI ) a hop limit severely limits the size of network it can be used in.
IS-IS and Internet
* Intermediate System-to-Intermediate System ( IS-IS ), an intradomain routing exchange protocol used in both the OSI and Internet environments ( ISO 10589 and RFC 1142 ).
One version of RIP served as one of the initial so-called interior gateway protocols for the growing Internet, before the arrival of the more modern OSPF and IS-IS.
IS-IS and Engineering
MPLS Traffic Engineering relies upon the use of TE extensions to Open Shortest Path First ( OSPF ) or Intermediate System To Intermediate System ( IS-IS ) and RSVP.
IS-IS and similar
Intermediate System To Intermediate System ( IS-IS ), usually called is-is, is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices.
IS-IS and protocol
Networking advances IEEE 802. 1aq ( SPB ) include the use of the link-state routing protocol IS-IS to allow larger networks with shortest path routes between devices.
NSAP-style addresses are used in the IS-IS routing protocol.
IS-IS ( pronounced " i-s i-s ") is an interior gateway protocol, designed for use within an administrative domain or network.
IS-IS is a link-state routing protocol, operating by reliably flooding link state information throughout a network of routers.
Like the OSPF protocol, IS-IS uses Dijkstra's algorithm for computing the best path through the network.
This has contributed to IS-IS as an ISP-scale protocol.
IS-IS, another link-state dynamic routing protocol, is more common in large service provider networks.
CLNP is widely used in many telecommunications networks around the world because IS-IS ( an OSI layer 3 protocol ) is mandated by the ITU-T as the protocol for management of Synchronous Digital Hierarchy ( SDH ) elements.
* IS-IS, network routing protocol
IS-IS and called
IS-IS has been called " the de facto standard for large service provider network backbones.
IS-IS and OSPF
Dijkstra's algorithm is used in SPF, Shortest Path First, which is used in the routing protocols OSPF and IS-IS.
Interior routing mostly uses link-state routing protocols such as OSPF and IS-IS.
IS-IS differs from OSPF in the way that " areas " are defined and routed between.
The logical view is that OSPF creates something of a spider web or star 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.
IS-IS also differs from OSPF in the methods by which it reliably floods topology and topology change information through the network.
* OSPF and IS-IS: A Comparative Anatomy by Dave Katz, Juniper
* IS-IS and OSPF difference discussion ( Vishwas Manral, Manav Bhatia and Yasuhiro Ohara )
RFC 3717 documents work in optical routing for IP, based on " constraint-based " extensions to OSPF and IS-IS.
As a result, the shortest path first is widely used in network routing protocols, most notably IS-IS and OSPF ( Open Shortest Path First ).
Examples of link-state routing protocols include OSPF and IS-IS.
Link-state routing protocols such as Open Shortest Path First ( OSPF ) and IS-IS elect a designated router on every link to perform flooding of topology information.
Since link-state routing requires the topology database to be synchronized across the network, OSPF and IS-IS perform topology flooding using a reliable algorithm.
Protocols that support some form of adjacency setup, such as OSPF or IS-IS, may also be used to bootstrap a BFD session.
BFD's operation in conjunction with Open Shortest Path First ( OSPF ) and IS-IS protocols has also been outlined in RFC 5881.
IS-IS and .
Each IS-IS router independently builds a database of the network's topology, aggregating the flooded network information.
IS-IS does not use IP to carry routing information messages.
IS-IS is neutral regarding the type of network addresses for which it can route.
This allowed IS-IS to be easily used to support IPv6.
IS-IS routers build a topological representation of the network.
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.
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