Differences between IGMP snooping and IGMP proxy

Original link http://louisnetwork.blog.sohu.com/111972027.html

 

Some tests involve IGMP snooping at work. When it comes to IGMP snooping, it is inevitable that IGMP proxy will come to mind. Sometimes, you may think more and think more about it.
What is the difference between them? First, let's look at the figure below. L2 Switch enables IGMP snooping, and router1 is a remote multicast router that uses the PIM protocol to forward multicast packets.

Pim has never been used or studied. Like IGMP, It is a multicast routing protocol. There are several hundred pages of RFC.
The following is its definition,Protocol-Independent Multicast (PIM)Is a family of multicast routing protocols that can provide one-to-operate and distribute-to-distribute distribution of data over the Internet. the "protocol-independent" part refers to the fact that Pim does not include its own topology discovery mechanic, but instead uses routing information supplied by other traditional routing protocols such as Border Gateway Protocol (BGP ).

The function of enabling IGMP snooping is to listen for IGMP report, query, and leave information between IGMP router and IGMP client. In this process, for IGMP report, it records the port on which GDA (group Destination Address) MAC address is associated in the Mac filter database of the switch.
For leave message (IGMP V2), when the switch receives the leave message from the client, the switch sends a group query to check whether the PC in this group is actually absent. If no reply is received, the entry will be deleted.
If there is no leave message in igmpv1, the IGMP router periodically sends 224.0.0.1 queries, and the switch sends the related port according to the database. If no response is returned three times in a row, the entry will be deleted.

What are the advantages of IGMP snooping? After talking so much, you should understand it ..
1. After a switch that does not support IGMP snooping receives the multicast packet, it will flood to each port, because its MAC address is GDA (01: 00: 5E: XX), there is no such entry in the switch, which can save bandwidth.
2. access can be controlled for paid programs.

Next let's take a look at IGMP proxy,
Topo is the same as above, except that IGMP proxy is enabled on Layer2 switch.
Proxy means proxy, which is similar to HTTP proxy and ARP proxy process.
IGMP router creates a multicast table by intercepting IGMP packets. The functions of the table are divided into two parts,
1. the uplink port executes the host role, and the downlink port executes the router role.
The uplink port executes the host role and responds to the query from the vro. When a new user group or the last user in a group exits, it actively sends the member report package or leaves the package.
The downlink port executes the role of the router in full accordance with the mechanism specified in IGMP, including the queryers' election mechanism, regularly sends general query information, and sends specific queries when receiving the exit packet.

The implementation mechanism of IGMP snooping is: the switch listens to the host to report messages to the IGMP members of the router to form the correspondence between group members and switch interfaces; based on this relationship, the vswitch transfers multicast packets to APIs with group members only.
IGMP proxy and IGMP snooping have the same functions but different mechanisms: IGMP snooping only obtains relevant information by listening to IGMP messages, the IGMP proxy intercepts the IGMP request of the end user and then forwards it to the upper-layer router.
The table formed in IGMP snooping is the correspondence between group members and vswitch interfaces. In IGMP proxy, the multicast route table is formed.
Equivalent to IGMP snooping, it implements the IGMP proxy L2 network device, takes the server role on the user side, regularly queries user information, and assumes the client role on the network routing side, send the current user information to the network as needed. it not only can suppress the spread of layer-2 multicast, but also can effectively obtain and control user information. It also plays a role in reducing network-side protocol messages and reducing network load.