Multicast routers use IGMP v2.0 to learn which groups have members on each of their attached physical networks. A multicast router keeps a list of multicast group memberships for each attached network, and a timer for each membership. "Multicast group memberships" means the presence of at least one member of a multicast group on a given attached network, not a list of all of the members.

When a host receives a General Query, it sets delay timers for each group (excluding the all-systems group) of which it is a member on the interface from which it received the query.

When a router receives a Report, it adds the group being reported to the list of multicast group memberships on the network on which it received the Report and sets the timer for the membership to the [Group Membership Interval].

When a host joins a multicast group, it should immediately transmit an unsolicited Version 2 Membership Report for that group, in case it is the first member of that group on the network

When a host leaves a multicast group, if it was the last host to reply to a Query with a Membership Report for that group, it SHOULD send a Leave Group message to the all-routers multicast group.

3.9 Stack

Stacking function is convenient for administrator to manage multiple switches by single IP. Basically, you got to have min. 2 units,

Step 1: linking the switches by one category 5 or fiber cable.

Step 2: Choose either one management switch as Master switch, key in its IP number (ex:203.70.249.152).

Step 3: Choose “Stack Config”.

Step 4: Choose “enable” of Stacking State, and “Save”.

Figure 3-8 The Stack screen page

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