Hybrid Routing Explained

Hybrid routing takes the advantages of distance vector and link state routing and merges them into a new routing. Technically, it is based on distance vector routing, but it contains many features and advantages of link state routing. RIPv2, EIGRP, and BGP are examples of Hybrid routing.

There are three types of routing: distance vector, link state, and hybrid. Each routing type uses a different approach to select the best path from all available paths for every subnet in the network.

Distance vector routing uses hop counts (number of routers on the route) to select the best route. It works well in a small network where all links have identical bandwidth. If links have different bandwidths or the network size is big, it does not work properly.

To support a large network or a network with links of mixed bandwidth, link state routing was created. Link state routing uses bandwidth and other parameters to select the best route. It discovers all network routes and runs a complex algorithm on them to select the best path for every destination in the network. Link state routing is fast, secure, and stable. It supports all types of networks. But it also has some disadvantages. It consumes more CPU and RAM than routing methods.

To reduce CPU and RAM usage while maintaining all the core functionality of link state routing, a new type of routing called hybrid routing was created. Hybrid routing uses the core features of distance vector and link state routings. When processing routing updates, it works like distance vector routing. It reduces the CPU and memory overhead. When sending routing updates, it acts like link state routing. It sends incremental, reliable updates via multicast messages.

EIGRP and BGP use hybrid routing. EIGRP is a Cisco proprietary protocol. It works only on Cisco routers. It consumes less CPU and RAM than link state routing protocols but supports all core features and functions of link state routing. It is an IGP protocol. It supports VLSM, route summarization, trigger, and incremental updates. It uses multicast to send routing updates.

BGP is based on a standard (RFC 1772). It is used to interconnect ISPs on the Internet. Unlike other routing protocols that use multicasts or broadcasts for routing updates, it sets up a TCP connection on port 179 to a neighboring peer and uses it to share routing updates. It supports route summarization. It provides connectivity between different autonomous systems.

Key points:-

  • Hybrid routing is a combination of distance vector and link state routing.
  • It is optimized to provide core functions of link state routing while using fewer hardware resources like distance vector routing.
  • It scales all types of networks.
  • It is easier to configure, manage, and troubleshoot than link state routing.

ComputerNetworkingNotes CCNA Study Guide Hybrid Routing Explained