3.2 Layer 3 multicast

doyle never goes away… multicast:

on a multiaccess network, OSPF DRothers send updates to the OSPF DR and BDR at 224.0.0.6; the DR sends packets to the DRothers at 224.0.0.5.

Some Well-Known Reserved Multicast Addresses
Address Group
224.0.0.1 All systems on this subnet
224.0.0.2 All routers on this subnet
224.0.0.4 DVMRP routers
224.0.0.5 All OSPF routers
224.0.0.6 OSPF designated routers
224.0.0.9 RIP-2 routers
224.0.0.10 EIGRP routers
224.0.0.13 PIM routers
224.0.0.15 CBT routers
224.0.1.39 Cisco-RP-Announce
224.0.1.40 Cisco-RP-Discovery