Extreme Networks ExtremeWare Command Reference Manual page 894

IGP Commands
The Intermediate System to Intermediate System (IS-IS) routing protocol is a link-state protocol that is
very similar to OSPF. ExtremeWare Integrated IS-IS support allows switches to act as IP-only IS-IS
routers.
The IS-IS routing protocol provides transport-independent routing. IS-IS partitions the network into
"routing domains." Routing domain boundaries are defined by interior and exterior links. Interior links
are part of the IS-IS routing domain; exterior links are not. No IS-IS routing messages are sent on
exterior links.
Routing Information Protocol (RIP) is an Interior Gateway Protocol (IGP) first used in computer routing
in the Advanced Research Projects Agency Network (ARPAnet) as early as 1969. It is primarily
intended for use in homogeneous networks of moderate size.
To determine the best path to a distant network, a router using RIP always selects the path that has the
least number of hops. Each router that data must traverse is considered to be one hop.
The routing table in a router using RIP contains an entry for every known destination network. Each
routing table entry contains the following information:
• IP address of the destination network
• Metric (hop count) to the destination network
• IP address of the next router
• Timer that tracks the amount of time since the entry was last updated
The router exchanges an update message with each neighbor every 30 seconds (default value), or if
there is a change to the overall routed topology (also called triggered updates). If a router does not
receive an update message from its neighbor within the route timeout period (180 seconds by default),
the router assumes the connection between it and its neighbor is no longer available.
A new version of RIP, called RIP version 2 (RIPv2), expands the functionality of RIP version 1 to
include:
• Variable-Length Subnet Masks (VLSMs)
• Next-hop addresses
• Support for next-hop addresses allows for optimization of routes in certain environments
• Multicasting
If you are using RIP with supernetting/Classless Inter-Domain Routing (CIDR), you must use RIPv2
only, and RIP route aggregation must be turned off.
894 ExtremeWare Software 7.0.0 Command Reference Guide