What separates areas in IS-IS?
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A. B. C. D.D
IS-IS differs from OSPF in the way that "areas" are defined and routed between. IS-IS routers are designated as being: Level 1 (intra-area); Level 2 (inter area); or
Level 1-2 (both). 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. Level 1-2 routers exchange information with both levels and are used to connect the inter area routers with the intra area routers.
https://en.wikipedia.org/wiki/IS-ISIn the Intermediate System-to-Intermediate System (IS-IS) routing protocol, areas are separated by routers known as Designated Intermediate System (DIS). The correct answer is B.
IS-IS is a link-state routing protocol that uses the shortest path first (SPF) algorithm to compute the shortest path to a destination. The network topology is represented by a link-state database (LSDB), which contains information about the status of all links in the network.
IS-IS divides the network into areas, similar to OSPF. Areas provide a way to partition a large network into smaller, more manageable domains, reducing the size of the LSDB and improving the efficiency of the SPF calculation. Each area is identified by a unique 8-byte Area ID, which is assigned by the network administrator.
Within an area, all routers maintain an identical LSDB, which includes information about all the routers and links within the area. Routers within an area communicate with each other using Link State Protocol Data Units (LSPs) to synchronize their LSDBs.
The DIS is responsible for maintaining the LSDB for the area and flooding LSPs to other routers within the same area. Each area must have at least one DIS, and the router with the highest priority value is elected as the DIS. If two routers have the same priority value, the router with the highest MAC address is elected.
Pseudo-nodes are used in IS-IS to represent subnetworks or broadcast segments. They are not routers themselves, but rather logical entities that represent the state of the subnetwork. Pseudo-nodes are identified by a unique 6-byte System ID and a 2-byte Circuit ID.
In conclusion, areas in IS-IS are separated by routers known as Designated Intermediate System (DIS). These routers are responsible for maintaining the LSDB for the area and flooding LSPs to other routers within the same area. Pseudo-nodes are used to represent subnetworks or broadcast segments.