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Community Member

quick eigrp question

When routers become eigrp neighbours, Do they exchange topology , or routing tables?

would all networks be in 1 update packet, to each router, then once say router A recieved router B's info, would it advertise back to router B networks learned at infinate metric ?

cheers

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Accepted Solutions
Cisco Employee

Re: quick eigrp question

Hello Carl,

When routers become eigrp neighbours, Do they exchange topology , or 
routing tables? 

While synchronizing the EIGRP database, a router sends the best entry for each network from its EIGRP topology database if that entry has also been inserted into the router's routing table. In effect, this is the same as sending all EIGRP routes from a router's routing table to its neighbor.

would all networks be in 1 update packet

Not necessarily. A single IP packet will carry multiple EIGRP route entries but if the EIGRP database is large, it may require several IP packets to be sent.

then once say router A recieved router B's info, would it advertise back
 to router B networks learned at infinate metric ?

Yes but only if the router A considers the router B to be the successor for the networks B has advertised to A.

Best regards,

Peter

2 REPLIES
Cisco Employee

Re: quick eigrp question

Hello Carl,

When routers become eigrp neighbours, Do they exchange topology , or 
routing tables? 

While synchronizing the EIGRP database, a router sends the best entry for each network from its EIGRP topology database if that entry has also been inserted into the router's routing table. In effect, this is the same as sending all EIGRP routes from a router's routing table to its neighbor.

would all networks be in 1 update packet

Not necessarily. A single IP packet will carry multiple EIGRP route entries but if the EIGRP database is large, it may require several IP packets to be sent.

then once say router A recieved router B's info, would it advertise back
 to router B networks learned at infinate metric ?

Yes but only if the router A considers the router B to be the successor for the networks B has advertised to A.

Best regards,

Peter

Community Member

Re: quick eigrp question

Hi There

Can you please elaborate on the following statement

"Yes but only if the router A considers the router B to be the successor for the networks B has advertised to A."

so are you saying under normal operation, when router A and B exchange routes, if B was the successor for 2 of the routes, would A then advertise these back 2 A with infinate metric (poisened route)

?

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