Unanswered Question
Oct 14th, 2007

It is given in eigrp that it will only send partial update and the update is automatically

bounded so that only those router that need the update the information are updated.

What does it mean could anyone help with an ex.

Thanks in advance.

I have this problem too.
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guruprasadr Sun, 10/14/2007 - 20:45

HI Vishwa,

As like RIP the EIGRP will not advertise its entire routing table for every updates rather it will synchronize its neighbour only with the modified routes in the table.

Any Routes in the Routing Table this is modified / removed / added will be updated via Routing Updates.


Best Regards,

Guru Prasad R

vishwancc Sun, 10/14/2007 - 22:14

hi Guru,

I don't think i was clear enough.

What i am asking is how will Eigrp know that it have to send the update to only specific router,won't it be sending to all the neighbors, and in the partial update will it eigrp only be sending information about the link that is down or all the route learned from the neigbor.


bvsnarayana03 Mon, 10/15/2007 - 00:35

This is how I remember, may be it could help you.

EIGRP updates are: Non-periodic, partial & Bounded.

Non-periodic: updates not sent at regular intervals, but only when topology change occurs.

Partial: updates doesn't include full routing table but only routes that have changed.

Bounded: updates are only sent to the affected routers.

There are 3 tables maintained by EIGRP: Routing table, neighbor table & topology table. Since EIGRP work on DUAL algorithm, it computes Successor & Feasible successor & stores the information in topology table. In case of any route changes, it first updates the sucessor & feasible successor instead of all neighbors. However, remember that HELLOs are exchanged between all neighbors. In case successor or feasible succesor becomes unavailable, DUAL is run again to populate topology table.

ariesc_33 Mon, 10/15/2007 - 03:57

Assuming that successor or feasible successor becomes unavailable, then all routers in the domain has to be informed with the changes and all routers has to find (DUAL) the best path to each destination. I believe this is one of the disadvantage of EIGRP compared to OSPF.

vishwancc Tue, 10/16/2007 - 21:02


i am still not clear i am looking for answer of line

Bounded: updates are only sent to the affected routers.

How it will know these are the effected routers

guruprasadr Tue, 10/16/2007 - 22:02

HI Vishwa, [PLS RATE if HELPS]

EIGRP does not send updates using a broadcast address; instead, it sends them to the multicast address (all EIGRP routers).

EIGRP sets updates only when necessary and sends them only to neighboring routers. There is no periodic update timer.

EIGRP discovers and maintains information about its neighbors. It multicasts hello packets ( every 5 seconds for most networks. The router builds a table with EIGRP neighbor information. The holdtime to maintain a neighbor is three times the hello time: 15 seconds. If the router does not receive a hello in 15 seconds, it removes the neighbor from the table.

NOTE: Whenever there is a CHANGE in the routing table ie., the neighbor is removed or new neigbor is added the Routing Table is advertised.

Hope I am Informative.


Best Regards,

Guru Prasad R


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