Root: WRM Database > Information Technology > Certifications > CCNA > Comparing > EIGRP vs. OSPF > DRs and BDRs > How EIGRP Exchanges Topology Information
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > EIGRP > Distributing Topology Information > How EIGRP Exchanges Topology Information
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > EIGRP > EIGRP Update Messages > How EIGRP Exchanges Topology Information
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > EIGRP > Hello Messages > How EIGRP Exchanges Topology Information
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > EIGRP > Multicast IP Address > How EIGRP Exchanges Topology Information
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > EIGRP > No DR or BDR like OSPF > How EIGRP Exchanges Topology Information



How EIGRP Exchanges Topology Information


EIGRP uses EIGRP Update messages to send topology information to neighbors. These messages can be sent to multicast IP address 224.0.0.10 if the sending router needs to update multiple routers on the same subnet; otherwise, the updates are sent to the unicast IP address of the particular neighbor. (Hello messages are always sent to the 224.0.0.10 multicast address.) Unlike OSPF, there is no concept of a Designated Router (DR) or Backup Designated Router (BDR), but the use of multicast packets on LANs allows EIGRP to exchange routing information with all neighbors on the LAN efficiently.







References

Odom, Wendell (2008) CCNA ICND2 Official Exam Certification Guide, Second Edition. Indianapolis: Cisco Press.