OSPFv2 and OSPFv3 Similarities

OSPFv3 shares many features with OSPFv2. OSPFv3 is a link-state routing protocol that uses the Dijkstra shortest path first (SPF) algorithm to select the best paths through the network. OSPFv3 routers are organized into areas, with all areas touching area 0 (the backbone area). OSPFv3 routers communicate with their neighbors using Hellos; exchange Link-State Advertisements (LSAs) and Database Descriptors (DBDs); and run the SPF algorithm against the accumulated link-state dat..

Weight Issues

In recent years, Data Centers have had to accommodate increasingly high structural loads. Data Center devices big and small have gotten heavier, putting greater strain on the rooms and buildings that house them. When designing your server environment, it is prudent to prepare for equipment that can weigh 1500 pounds (680.3 kg), 2000 pounds (907.2 kg), or even more, in a single cabinet location. (Even if your room doesn't have to support such massive equipment today, it may ne..

Basic Principles of Area Routing

IP subnets are treated as leaf-objects in the IS-IS SPF tree. Areas—recognized by the format of their NET—produce a summary into Level 2 and the Level 1-2 router and introduce a default route back into Level 1.  Routing to destinations within an area is straightforward. The first IS matches the destination to an entry in its routing table and selects the shortest path in exactly the same way OSPF would.  Routing between areas is only slightly complicated. The ..

Flooding on Broadcast Networks

Flooding is optimal over the broadcast network when the IS creates a pseudonode. For each pseudonode, a DIS is responsible for creating and updating the pseudonode LSP and for conducting the flooding over the LAN. Unlike OSPF, there is no backup DIS. The DIS sends CSNP every 10 seconds; the LSP is not acknowledged. If a router notices that part of its database is missing or that the entry in its database is old, it sends a PSNP requesting a newer copy of the LSP.   ..

Finding an IP Route

The EXEC level command to look at the entire IP routing table is: Router>show ip routeCodes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP    ..