area 0 ccna

area 0 ccna.(4) Depending on other conditions, R1 either immediately removes the route to 172.30.22.0 from its routing table, or marks the route as useless (with the "infinite" metric) and removes it a few minutes later.By the end of this process, router R1 determines that the previous route to subnet 172.30.22.0/24 is no longer valid, which allows R1 to not perform any loopback IP routing.Each routing protocol has its own definition of the "infinity" metric. 16 is used by RIP, as shown, while 15 is a valid metric for available routes. 232 -1 has always been used by EIGRP as "infinity" (slightly larger than 4 billion), and some Newer IOS versions define this value as 2*-] (over 10,OSPFv2 uses 224-1 as "infinite".EIGRP as an Advanced DV ProtocolEIGRP works somewhat like a DV protocol and somewhat unlike other protocols. Frankly, over the years, different Cisco documents and various books (including mine) have categorized EIGRP as either a self-contained, balanced hybrid routing protocol, or as some sort of advanced DV protocol.Regardless of the label given to EIGRP, the protocol uses several features that are either similar to basic DV protocols, such as RIP, or very similar. The following pages describe how RIP and EIGRP are similar and how they differ. EIGRP sends partial update messages on demandEIGRP does not use a short periodic update timer to send full updates on all routes, as RIP does; EIGRP sends a "persistent" message, and when the router gets this information, it sends information about each route once. The router then sends only partial1.2 Basics 193updates.194 Chapter 9 Understanding EIGRP Concepts An EIGRP partial update is an update message that lists information about routes that have been added or have changed. For example, when a router interface fails, the partial route is affected. That router sends a direct partial update message to all other neighboring EIGRP routers listing the new information. Or, when a new route becomes available, the router sends a partial update listing only the new route. These update messages are not complete updates, as they include only changed or new information. This concept is somewhat like the OSPF practice of doing an LSA as soon as it appears in an area. but the router creating the SPF LSA does not send that LSA again every 30 minutes. and EIGRP does not even send its routing information again. For example, if the routing information about a route has not changed for a year, EIGRP will not react to it in an update message strictly for the year after it first advertises the route.