• सुखार्थी त्यजते विद्यं विध्यार्थी त्यजते सुखम्सु sखर्थीन: कुतॊ विद्या कुतॊ विध्यार्थीन: सुखम् ||
  • “Luxury people leave knowledge, but a student leaves Luxury No knowledge for one who seeks Luxury, No luxury for student”
  • न चोर हार्यं न च राज हार्यं न भात्रू भाज्यं न च भारकारि |व्ययं कृते वर्धत एव नित्यं विद्याधनं सर्वधनप्रधानम ||
  • Cannot be snatched away by thief, cannot be snatched away by king, Cannot be divided among brothers, Not heavy either If spent daily, it always keeps growing. The wealth of knowledge is the precious of wealth of all”

Distance Vector Routing Protocol




Distance Vector Routing / Bellman Ford Algorithm

Distance Vector Routing or Bellman Ford Algorithm is a type of algorithm used by routing protocols to learn routes on an interconnected network. Routing protocols that use distance-vector routing protocols include:

1.     Routing Information Protocol RIP.

2.     Cisco's Internet Gateway Routing Protocol IGRP.

3.     Apple's Routing Table Maintenance Protocol RTMP.

In distance vector routing when a router is booted it maintains a routing table advertising vector of distance and direction. Direction is represented by next hop address, whereas Distance uses metrics such as hop count.

After every fixed period of time router exchanges its routing table with its neighbouring router and we get a new merged table.


Example

For the given network explain how routing tables are updated using distance vector routing algorithm / Bellman-Ford Algorithm.

Solution: When Routers are booted Routers gathers information from attached networks and maintains  following routing tables: 

Step 1:   After a fixed period of time routing tables of the neighboring tables are shared: 

  1. Router A swaps its information with Router B , Router C  and Router D.
  2. Router B swaps its information with Router A and Router C
  3. Router C swaps its information with Router A, Router B and Router E
  4. Router D swaps its information with Router A
  5. Router E swaps its information with Router C Step 2:   After a fixed period of time updated routing tables of the neighboring tables are shared: 

    1. Router A swaps its information with Router B , Router C  and Router D.
    2. Router B swaps its information with Router A and Router C
    3. Router C swaps its information with Router A, Router B and Router E
    4. Router D swaps its information with Router A
    5. Router E swaps its information with Router C