Distance vector routing protocol is a routing protocol that allows the router route an arriving packet to its distance. Distance vector uses Bellman-Ford Algorithm where it uses 2 methods to send the packet:
1. It calculates its distance to the destination by hop counting
2. It uses its vector to direct the router where to send its packet to (the next router or hop) in order to reach the destination
The DV protocol is suitable for smaller and stable environment because a DV protocol takes a long time to converge which is a drawback. Also a drawback is that DV cannot distinguish speeds of the lines. Therefore, a directly connected E1 line or a directly connected 56 kbps line will be considered the same. Another disadvantange is that RIP and IGRP broadcasts its routing table every 30 seconds and 90 seconds whether there is a change in the network topology or not. This behavior will waste unnecessary bandwidth. However, DV has its advantages which is less overhead and less computation.
To shorten the convergence of the networks and possible looping occurrences, route poisoning is applied. By using route poisoning, the maximum hop counts is limited to 15. When the hop count is 16, the packet will be dropped. Also, when a router is down, it will set the destination to it as infinity (16 hops) and will 'poisen' the route to that router.
Protocols that uses distance vector routing is RIPv1, RIPv2, IGRP and EIGRP.
The characteristics of RIPv1 are:
- updates broadcasts every 30 sec to 255.255.255.255 despite there is a change it its topology or not.
- uses classfull protocol thus not supporting VLSM
- equal cost sharing is set as a default feature
- max hop counts = 15 hops (16 hops is considered as infinite)
- does not support clear-text or MD5 authentication
- route max = 25 routes. For more than 25 routes, another packet must be generated.
The characteristics of RIPv2 are:
- updates multicasts every 30 sec to 224.0.0.9 despite there is a change it its topology or not.
- uses classless protocol thus supports VLSM
- equal cost sharing is set as a default feature
- max hop counts = 15 hops (16 hops is considered as infinite)
- does support clear-text or MD5 authentication. MD5 authentication is recommended since the password is encrypted.
- route max = 25 routes. For more than 25 routes, another packet must be generated.
The characteristics of IGRP are:
- updates broadcasts every 90 sec to 255.255.255.255 despite there is a change it its topology or not.
- uses classfull protocol thus not supporting VLSM
- this protocol is Cisco proprietary protocol
- equal cost can be enabled with variance command
The characteristics of EIGRP are:
- updates multicasts to 224.0.0.10. A full routing table multicast will be sent when an adjecency is formed. When there is a change in the network, only the change of the topology will be updated.
- uses DUAL algorithm
- equal cost can be enabled with variance command
-- 22 December 2010 --
1. It calculates its distance to the destination by hop counting
2. It uses its vector to direct the router where to send its packet to (the next router or hop) in order to reach the destination
The DV protocol is suitable for smaller and stable environment because a DV protocol takes a long time to converge which is a drawback. Also a drawback is that DV cannot distinguish speeds of the lines. Therefore, a directly connected E1 line or a directly connected 56 kbps line will be considered the same. Another disadvantange is that RIP and IGRP broadcasts its routing table every 30 seconds and 90 seconds whether there is a change in the network topology or not. This behavior will waste unnecessary bandwidth. However, DV has its advantages which is less overhead and less computation.
To shorten the convergence of the networks and possible looping occurrences, route poisoning is applied. By using route poisoning, the maximum hop counts is limited to 15. When the hop count is 16, the packet will be dropped. Also, when a router is down, it will set the destination to it as infinity (16 hops) and will 'poisen' the route to that router.
Protocols that uses distance vector routing is RIPv1, RIPv2, IGRP and EIGRP.
The characteristics of RIPv1 are:
- updates broadcasts every 30 sec to 255.255.255.255 despite there is a change it its topology or not.
- uses classfull protocol thus not supporting VLSM
- equal cost sharing is set as a default feature
- max hop counts = 15 hops (16 hops is considered as infinite)
- does not support clear-text or MD5 authentication
- route max = 25 routes. For more than 25 routes, another packet must be generated.
The characteristics of RIPv2 are:
- updates multicasts every 30 sec to 224.0.0.9 despite there is a change it its topology or not.
- uses classless protocol thus supports VLSM
- equal cost sharing is set as a default feature
- max hop counts = 15 hops (16 hops is considered as infinite)
- does support clear-text or MD5 authentication. MD5 authentication is recommended since the password is encrypted.
- route max = 25 routes. For more than 25 routes, another packet must be generated.
The characteristics of IGRP are:
- updates broadcasts every 90 sec to 255.255.255.255 despite there is a change it its topology or not.
- uses classfull protocol thus not supporting VLSM
- this protocol is Cisco proprietary protocol
- equal cost can be enabled with variance command
The characteristics of EIGRP are:
- updates multicasts to 224.0.0.10. A full routing table multicast will be sent when an adjecency is formed. When there is a change in the network, only the change of the topology will be updated.
- uses DUAL algorithm
- equal cost can be enabled with variance command
-- 22 December 2010 --
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