- Packages required: multicast
- Incompatible with: routing-test (v3)
Internet Group Management Protocol (IGMP) proxy can be used to implement multicast routing. It is forwarding IGMP frames and commonly is used when there is no need for more advanced protocol like PIM.
IGMP proxy features:
- The simplest way how to do multicast routing;
- Can be used in topologies where PIM-SM is not suitable for some reason;
- Takes slightly less resources than PIM-SM;
- Ease of configuration.
On the other hand, IGMP proxy is not well suited for complicated multicast routing setups. Compared to PIM based solutions, IGMP proxy does not support more than one upstream interface and routing loops are not detected or avoided.
By default, IGMP proxy upstream interface will send IGMPv3 membership reports and it will detect what IGMP version the upstream device (e.g. multicast router) is using based on received queries. In case IGMPv1/v2 queries are received, the upstream port will fallback to lower IGMP version. It will convert back to IGMPv3 when IGMPv1/v2 querier present timer (400s) expires. Downstream interfaces of IGMP proxy will only send IGMPv2 queries.
To forward all multicast data coming from ether1 interface to all other interfaces, where subscribers are connected:
[admin@MikroTik] /routing igmp-proxy> interface add interface=ether1 upstream=yes [admin@MikroTik] /routing igmp-proxy> interface add interface=all [admin@MikroTik] /routing igmp-proxy> interface print Flags: X - disabled, I - inactive, D - dynamic, U - upstream # INTERFACE THRESHOLD 0 U ether1 1 1 all 1 2 D ether2 1 3 D ether3 1
You may also need to configure alternative-subnets on upstream interface - in case if the multicast sender address is in an IP subnet that is not directly reachable from from the local router.
[admin@MikroTik] /routing igmp-proxy> interface set [find upstream=yes] \ alternative-subnets=126.96.36.199/24,188.8.131.52/24
- query-interval (time, 00:00:01 - 01:00:00) : how often to send out IGMP Query messages over downstream interfaces.
- query-response-interval (time, 00:00:01 - 01:00:00) : how long to wait for responses to an IGMP Query message.
- quick-leave (yes|no) : specifies action on IGMP Leave message. If quick-leave is on, then an IGMP Leave message is sent upstream as soon as a leave is received from the first client on the downstream interface. Use set to yes only in case there is only one subscriber behind the proxy.
/routing igmp-proxy interface
Used to configure what interfaces will participate as IGMP proxy interfaces on router. If an interface is not configured as IGMP proxy interface, then all IGMP traffic received on it will be ignored.
- alternative-subnets (list of IP prefixes) : by default, only packets from directly attached subnets are accepted. This parameter can be used to specify a list of alternative valid packet source subnets, both for data or IGMP packets. Has effect only on upstream interface. Should be used when the source of multicast data often is in a different IP network.
- interface (interface name) : RouterOS interface
- threshold (integer) : minimal TTL; packets received with a lower TTL value are ignored
- upstream (yes|no) : interface is called "upstream" if it's in the direction of the root of the multicast tree. An IGMP forwarding router must have exactly one upstream interface configured. The upstream interface is used to sent out IGMP membership requests.
/routing igmp-proxy mfc
Multicast forwarding cache (MFC) status.
- group (IP address) : IGMP group address
- source (IP address) : multicast data originator address
- incoming-interface (interface name) : packet stream is coming in router through this interface
- outgoing-interface (interface name) : packet stream is going out of router through this interface
Static multicast forwarding cache (MFC) entries
Since RouterOS 4.5 MFC is enabled to add static multicast forwarding rules. If a static rule is added, all dynamic rules for that group will be ignored.
These rules will take effect only if IGMP-proxy interfaces are configured (upstream and downstram interfaces should be set) or these rules wont be active.
- downstream-interfaces (list of interfaces) : received stream will be sent out to listed interfaces only.
- group (multicast group address) : multicast stream group address this rule applies should be set
- source (IP address) : IP address we are receiving stream from should be set
- upstream-interface (interface) : interface that is receiving stream data should be set
Will forward stream unconditionally if it comes in from ether1 with set source and will be sent out to ether2, clients that will try to get stream on interface ether3 will not receive that stream.
/routing igmp-proxy interface add comment="" disabled=no interface=ether1 threshold=1 upstream=yes /routing igmp-proxy interface add comment="" disabled=no interface=ether2 threshold=1 /routing igmp-proxy interface add comment="" disabled=no interface=ether3 threshold=1 /routing igmp-proxy mfc add source=192.168.0.1 upstream-interface=ether1 \ downstream-interface=ether2 group=184.108.40.206 disabled=no
MFC static entry
220.127.116.11 group will not be sent at all
/routing igmp-proxy mfc add source=192.168.0.1 upstream-interface=ether1 \ group=18.104.22.168 disabled=no