IGMP - Layer 2 or Layer 3

dppagcdppagc Member Posts: 293
From what I read from books,

IGMP is communication from host to router - is it a L2 to L3 communication?

But IGMP snooping occurs at the L2 switch. So I assumes that it intercepts the frames?


  • OfWolfAndManOfWolfAndMan Member Posts: 923 ■■■■□□□□□□
    Technically Layer 3. There is no transport layer used in an IGMP packet.
    IGMP snooping is a layer 2 concept though, yes. IGMP in regards to forwarding logic is technically layer 2 yes as the message is local to the LAN and membership queries are only sent to the LAN. HOWEVER, structurally speaking, IGMP messages are sent in IP data grams with a TTL set to 1, so they can't leave the LAN, but they are encapsulated at Layer 3.

    Here is a captured frame for your reference. Hope this helps.

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