Although it is possible to have a router attach to more than three areas, the Cisco Technical Assistance Center (TAC) recommends that a greater number of areas be created only after careful consideration. The results of having more areas will vary depending on the router (memory and CPU), as well as network topology and how many LSAs are generated. Various sources recommend that the number of routers per area not exceed 40 to 80; however, this is a rough guideline and not a s..
Calculating the Cost of a Path to Another Area
OSPF calculates the costs of paths to other areas differently than it calculates paths to other routing domains. The path to another area is calculated as the smallest cost to the ABR, added to the smallest cost across the backbone. Thus, if there were two paths from the ABR into the backbone, the shortest (lowest-cost) path would be added to the cost of the path to the ABR. External routes are routes from another routing domain. External routes discovered by OSPF can ..
Access routers connect the customer or enterprise site to the distribution network. In the ISP case, the router at the remote end of an access link is typically the customer premises equipment, and may be owned and operated by the customer. For large enterprise networks, in which the LANs and WANs are managed by different divisions or contractors, the access router typically is managed by either the WAN or the LAN operator— usually this is the latter if the LA..
Cisco Secure Intrusion Detection System and Catalyst Services Modules
This section covers tools that are useful for managing network security. Cisco Secure IDS, formerly known as NetRanger, is designed to efficiently and effectively protect your network against intruders from inside and outside of your networking domain. Note The CCIE Security written exam still refers to the term NetRanger. The new CCIE Security exam no longer tests the NetSonar application. NetRanger is now commonly known as Cisco Secure Intrusion Detection System or Cisco ..
Reducing OSPF Traffic in Stable Networks
You can reduce the overhead due to OSPF LSA flooding by applying the interface-level command ip ospf flood-reduction: Router9#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router9(config)#interface Serial0/0 Router9(config-if)#ip address 192.168.10.9 255.255.255.0 Router9(config-if)#ip ospf flood-reduction Router9(config-if)#exit Router9(config)#end Router9# By default, OSPF will flood the area with all known LSAs every 3,600 seconds ..
