I hope this information will help you
EIGRP is sometimes referred to as a hybrid routing protocol because it has characteristics of both distance-vector and link-state protocols. For example, EIGRP doesn’t send link-state packets as OSPF does; instead, it sends traditional distance-vector updates containing information about networks plus the cost of reaching them from the perspective of the advertising router. And EIGRP has link-state characteristics as well—it synchronizes routing tables between neighbors at startup and then sends specific updates only when topology changes occur. This makes EIGRP suitable for very large networks. EIGRP has a maximum hop count of 255 (the default is set to 100).
(source : CCNA Study Guide by Todd Lammle)
Good and difficult question Umair!
I believe some of EIGRP DV properties are as follow:
- ability to send the full routing table as an update (but only when 2 neighbours first come up), with a simplified adjacency build-up process (as compared to OSPF where there are more criteria for 2 potential neighbours to become adjacent and start exchanging routing information). Again the process for OSPF neighbours to exchange routing informations is more complex with the exchange of DD packets before sending LSU-LSA and only the unknow LSU will be exchanged.
- ability to have a full view of the topology table (sh ip eigrp topo all-links) while OSPF routers (if the design is multi-areas) only keep full information about their local area with the subnets in other areas represented as LSA type 3.
The hybrid properties - to me - mean enhanced DV properties:
- EIGRP does NOT regularly send full routing table updates, only partial and triggered
- EIGRP infinity metric is e^32 (much improved from RIP = 16).
EIGRP Distance-vector properties include :
- An EIGRP router only advertises its best route to its neighbour , not every route that is aware of .
- An EIGRP router does not have a complete map of the topology , it is only aware of what its neighbours have told it ( routing by rumour )
EIGRP Link-state properties :
- An EIGRP router does form neighbour relationships
- Triggered updates . An update is only sent when a change in the topology occurs
another thing EIGRP has which no other protocol is able to: Unequal cost-path load balancing.
the most important enhancement is that it is Loop-free. Most of the rules needed to make RIP work (Count to infinity, hold-down-timer, poison-reverse) are not needed in EIGRP. This of course has downsides if you do not watch out and your design does not allow EIGRP to install a feasible successor. As always, there are side-effects... like medicine. The feasable successor makes EIGRP faster than most other protocols because it does not need to recalculate if the successor dies.
to be a little more precise here:
RIPv1 and IGRP (DV) are using Broadcasts via UDP520, no neighbor relationships
RIPv2 (DV) is using Multicast 220.127.116.11, UDP520, no neighbor relationships
OSPF (LS) uses 18.104.22.168 and 22.214.171.124, Protocol #89 , neighbor relationship with Hello's and confirmed updates
EIGRP (advanced DV) uses 126.96.36.199 , Protocol #88 , neighbor relationship with Hello's and confirmed updates
ISIS (LS, but quite a different animal) is not using L4 to propagate, it's a different encapsulation on Layer2, very scalable, more a provider protocol.
BGP (Path-Vector) uses TCP 179 and the neighbor does not need to be the next hop. A policy routing protocol
Fabrizio Chessa wrote:
- Distance-vector protocols use broadcast to send information about network
- Link-state protocols use multicast to send informationa about network topology
RIP v2 and EIGRP both send updates on multicast and both are the distance vector protocol. Only RIP v1 send update on broadcast.
Another thing RIP also have reply and request messages as EIGRP have.
Thanks & Regards,