Load Balancing with OSPF

Calculate Cost Ofospf

Load balancing is a standard functionality of Cisco IOS Software that is available across all router platforms. It is inherent to the forwarding process in the router, and it enables a router to use multiple paths to a destination when it forwards packets. The number of paths used is limited by the number of entries that the routing protocol puts in the routing table. Four entries is the default in Cisco IOS Software for IP routing protocols except for BGP. BGP has a default of one entry. The...

Load Balancing with EIGRP

Typically, networks are configured with multiple paths to a remote network. When these paths are equal or nearly equal, it makes sense to utilize all the available paths. Unlike Layer 2 forwarding, Layer 3 forwarding has the capability to load-balance between multiple paths. That is, the router can send frames out multiple interfaces to reduce the amount of traffic sent to a single network connection. The key to this feature is that the network paths must be of equal cost (or nearly equal for...

Link State and Advanced Distance Vector Protocols

In addition to distance vector-based routing, the second basic algorithm used for routing is the link-state algorithm. Link-state protocols build routing tables based on a topology database. This database is built from link-state packets that are passed between all the routers to describe the state of a network. The shortest path first algorithm uses the database to build the routing table. Figure 3-26 shows the components of a link-state protocol. Understanding the operation of link-state...

Route Summarization with VLSM

Routing Summarization

In large internetworks, hundreds or even thousands of network addresses can exist. In these environments, it is often not desirable for routers to maintain many routes in their routing table. Route summarization, also called route aggregation or supernetting, can reduce the number of routes that a router must maintain by representing a series of network numbers in a single summary address. This section describes and provides examples of route summarization, including implementation...

Using OSPF debug Commands

The debug ip ospf events output shown in Example 4-6 might appear if any of the following situations occur The IP subnet masks for the routers on the same network do not match. The OSPF hello interval for the router does not match the OSPF hello interval that is configured on a neighbor. The OSPF dead interval for the router does not match the OSPF dead interval that is configured on a neighbor. If a router that is configured for OSPF routing is not seeing an OSPF neighbor on an attached...