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--- advanced-firewall [2023/05/28 04:37] – [Firewall] -condense hogwild
+++ advanced-firewall [2023/05/28 05:39] (current) – [Multicast] -condense, list/explain additional features of new IGMPv2 messages hogwild
@@ Line 50: / Line 50: @@
   * LAN0 - Checking this means the LAN0 bridge will participate in IGMP proxy.
   * LAN1 - Checking this means the LAN1 bridge will participate in IGMP proxy.
-  * LAN2 - Checking this means the LAN2 bridge will participate in IGMP proxy/
+  * LAN2 - Checking this means the LAN2 bridge will participate in IGMP proxy.
   * LAN3 - Checking this means the LAN3 bridge will participate in IGMP proxy.
@@ Line 73: / Line 73: @@
 **Udpxy port**- This specifies the port on which you can recive Udpxy information from your router.\\  \\   \\  {{:pasted:20220118-190844.png}}\\  \\
-**Efficient Multicast Forwarding (IGMP Snooping) -** IGMP snooping allows the router's switch to facilitate discovery of IGMP clients. The goal is to send multicat multicast traffic only towards Ethernet ports with at least one multicast member(subscriber)? Use caution, as often, UPnP is often the only significant multicast application in use in digital home networks;
+**Efficient Multicast Forwarding (IGMP Snooping) -** IGMP snooping makes the router's switch facilitate discovery of Multicast IGMP clients. This will help to send multicast traffic only towards ports with at least one multicast subscriber, reducing overall multicast traffic.
-therefore, multicast network misconfiguration or other deficiencies can appear as UPnP issues rather than underlying network issues. If IGMP snooping is enabled on a switch, or more commonly a wireless router/switch, it will interfere with UPnP/DLNA device discovery (SSDP) if incorrectly or incompletely configured (e.g. without an active querier or IGMP proxy), making UPnP appear unreliable. Typical scenarios observed include a server or client (e.g. smart TV) appearing after power on, and then disappearing after a few minutes (often 30 by default configuration) due to IGMP group membership expiring. On this very topic please beware of the wireless multicast forwarding under [[advanced-wireless|Advanced Wireless]]
+However, caution is advised. IGMP Snooping can interfere with proper functioning of UPnP or DLNA. This can make Multicast configuration errors or deficiencies appear as UPnP issues. Enabling IGMP snooping on a router's/switch will interfere with UPnP/DLNA device discovery.  Specifically, it can interfere with SSDP protocol transmissions. If IGMP snooping is incorrectly or incompletely configured (say, without an active querier or IGMP proxy), this make UPnP appear unreliable.
-**Force IGMPv2** - IGMPv2 enhances the IGMP communication supporting additional messages/behavior to optimise the end-to-end communication between client and server. Possibly the most important being the "Group Leave" message which is lacking instead in IGMP v1.\\   \\
+A common symptom of this is a network host (say, a Smart TV) which appears after it's powered on, but then "disappears" from the network after a few minutes. To be more precise, often this period is 30 minutes. This is because the default setting for when IGMP group membership will expire. Please be aware of the wireless multicast forwarding setting in the the //Advanced///[[advanced-wireless|Wireless]] menu.
+**Force IGMPv2** - IGMPv2 enhances IGMP with additional messages/behavior to optimize end-to-end client-server communication. Perhaps the most important of these additional messages is the "Leave Group" message. When a host no longer wants to listen to a multicast group address, it will report to the router that it has stopped listening. In v1, the host simply stopped listening, without informing the router.
+Other features of IGMPv2 include:
+Group specific membership query. The router can now send a membership query for a specific group address. When the router receives a leave group message, it will use this query to check if there are still any hosts interested in receiving the multicast traffic.
+MRT (Maximum Response Time) field. This new field in query messages specifies how much time hosts have to respond to the query.
+Querier election process. When two routers are connected to the same subnet, only one of them should send query messages. Having an "election" process ensures only one router, the router with the lowest IP address, becomes the active querier.\\   \\

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