When you put "ip igmp join-group" on an interface, it acts not as a server or a client, but as a member of the group.
When the multicast address is ping'd, then any node listening on that address should respond. Try to ping 126.96.36.199 in an ospf environment.
There is not really a concept of server and clients in multicast, just members of the group (nodes litening on that IP address) and people sending to that address, could be a server streaming media, could be a ping ;)
The sender does not join the group. You only need to join a group if you want to have the data passed to you. An IP address is only needed to recieve traffic. When a PC boots up it send out a broadcast for a dhcp address to the network before it has an address.
If the sender is a member of the group, then, depending on the setup, it could recieve it packets back. But the sender is not usually in the group.
As for a security hole, I'm pretty sure that PC's sending data to eachother is not a security hole ;-)
In the "sh ip mroute" on a cisco router, the multicast routes have an S and a G entry. S is source ang G is group.
From CCO "The special notation of (S,G), pronounced "S comma G," enumerates an SPT in which S is the IP address of the source and G is the multicast group address. Using this notation, the SPT for the example in Figure 43-7 would be (188.8.131.52, 184.108.40.206). "
This document gives several answers on frequently asked questions for PFRv3 channel state behavior.
Q1: What are all the channel operational states from a BR (border role) perspective and what are the rules/conditions to be in each st...
The need was to reach an host inside a LAN through a VPN connection managed by the LAN gateway (Cisco 1921).
The LAN gateway performs NAT and there was a dedicate nat rule for the host i wanted to reach through VPN.
I couldn't connect to the hos...
We have 3 identical switches configured by someone else and would like to claim some of the Gigabit ports(G1/G2/G3/G4) for use on servers. When we try to change the wiring and configuration, we run in to connectivity issues. Attached is a des...