igmp
| When talking about IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP, we said that the information provided by this "commands" was used by the kernel to choose which multicast datagrams accept or discard. This is true, but it is not all the truth. Such a simplification would imply that multicast datagrams for all multicast groups around the world would be received by our host, and then it would check the memberships issued by processes running on it to decide whether to pass the traffic to them or to throw it out. As you can imagine, this is a complete bandwidth waste.What actually happens is that hosts instruct their routers telling them which multicast groups they are interested in; then, those routers tell their up-stream routers they want to receive that traffic, and so on. Algorithms employed for making the decision of when to ask for a groups traffic or saying that it is not desired anymore, vary a lot. Theres something, however, that never changes: how this information is transmitted. IGMP is used for that. It stands for Internet Group Management Protocol. It is a new protocol, similar in many aspects to ICMP, with a protocol number of 2, whose messages are carried in IP datagrams, and which all level 2-compliant host are required to implement |
Favorite (0)
ReplyHot Group
Fixed Network Info Community
Members:9595 Posts:9360
Members:9595 Posts:9360
Wireless Network Info Community
Members:2501 Posts:11275
Members:2501 Posts:11275
Support HedEx User Group
Members:14007 Posts:4900
Members:14007 Posts:4900
Core Network Info Community
Members:1125 Posts:14720
Members:1125 Posts:14720
Network OSS Club
Members:4641 Posts:1596
Members:4641 Posts:1596