Manual:Routing/Multicast

Applies to RouterOS: v3.x, v4.x

See also: Multicast Routing in RouterOS 3.x

Overview

Protocol Independent Multicast - Sparse Mode (PIM-SM or PIM) provides multicast and IGMP features to RouterOS.

PIM features:

• Manage rendezvous points
• Multicast routing information base management
• Distributing multicast over network

Requirements

For multicast to work on router running RouterOS these packages are required:

• system
• routing
• multicast

Multicast package is not compatible with RouterOS v3 routing-test package.

route pim

You can set settings that enable shortest-path-tree mode for multicast on RouterOS

• switch-to-spt-bytes (0..4294967295) :

Sets after what amount of bytes pim will switch to shortest-path-tree, thus avoiding unneeded data transmissions

• switch-to-spt-interval (time interval in seconds) :

Sets after what amount of time in seconds pim will switch to shortest-path-tree, thus avoiding unneeded data transmissions

interface

Configuration of interface of the router that will participate in multicast network. Interfaces that are not configured here (or in IGMP-Proxy) will discard multicast packets.

• alternative-subnets () : - if router can receive multicast streams over groups that are not in standard Class-D section then you have to set up this field, so these groups are recognised as multicast groups and will not be discarded.
• assert-override-interval () :
• assert-time () :
• comment () : - additional text information for the entry
• copy-from () : - use other, already configured entry as stencil for this new one
• disabled () : - state of the entry
• dr-priority () : - if for stream source more than one router with multicast support is available, then one with highest priority will become Designated router of that multicast stream and will handle stream delivery to RP. Higher value means higher priority.
• hello-holdtime () : - how long consider sender of hello packet received on interface in neighbour list. (usually 3.5 times of hello-period)
• hello-period () : - how often hellp packet will be sent over this interface.
• hello-trigerred-delay () : - when interface starts to participate in multicast cloud then this value is max time interface will wait before sending hello packet. That period of waiting is random from 0 to value set in this field.
• igmp-version () : - what IGMP protocol version to support on the interface.
• interface () : - interface name that will participate in multicast cloud with these settings.
• join-prune-holdtime () :
• join-prune-period () :
• override-interval () :
• propagation-delay () :
• protocols () : - what protocols to support on the interface
• require-hello () :
• tracking-support () :

rp

Rendezvous point configuration. Rendezvous point (RP) is a distribution point for multicast group, source provides its data to it, and if there are any subscribers, then RP will provide data to client. Note, that RP will always receive data stream if that exists.

• comment (text) : add comment to static RP entry
• copy-from (number) : creates another RP just like one you pointed to with number you used.
• disabled (yes, no) : used to change status of RP entry effectively disabling or enabling it.
• group (IP address or ip address with subnet mask) : sets what group this RP will be assigned to. Values accepted are class D ip addresses with mask, thus effectively marking multiple groups to this RP entry e.g. 224.10.10.0/24 will add 256 groups starting with 224.10.10.0 till 224.10.10.255.
• hash-mask-length () : when multicast group have multiple RPs, and they are same scope and same priority, then this value is compared. and so you can load balance this way.
• priority () : if several RPs are available for multicast group, and they are both with same scope, then RP with highest priority is chosen. Smaller non-negative value is considered of higher priority. Exmaple: priority of 100 is higher than priority of 101.
• address (ip address) : at what address you have to look for RP for multicast group specified in group field. If group is set to one of routers interfaces, it should be reachable through whole multicast network, if it not, you will have to set up rules in MRIB (multicast routing information base).

rp-candidates

Rendezvous point candidate configuration, when RP is elected for mutlicast group

• comment () :
• copy-from () :
• disabled () :
• group (multicast group address) : routes with will be chosen to be a group RP if no other RP will not participate with higher priority
• holdtime () : after what time next election will be initiated
• is-scope-zone () :
• priority () :
• interface () : to what interface to bind to if this router is elected as multicast groups RP

bsr-candidates

bootstrap router candidate configuration

• comment (text) : set text describing bsr-candidate list entry
• disabled (yes|no) : set state of the list entry
• hash-mask-length () :
• is-scope-zone () :
• priority () : priority of the router in bsr election
• scope-zone () :
• interface () : interface of the router that bsr-candidate will be attached to and if elected BSR

mrib

Multicast route information base - route information about where are what components of multicast cloud (sources, RPs)

• comment () :
• copy-from () :
• destination () :
• disabled () :
• metric () :
• gateway () :

igmp-group

• interface () :
• group () :
• source () :
• last-reported () :
• timeout () :

neighbors

This menu only allows to see information about multicast routers that are reachable within one ethernet from all interfaces participating in multicast routing. This list is created and updated automatically according to state of multicast network.

• address (ip address) : - ip address of neighbour mutlticast router that router have received hello packet.
• interface (text) : - on what interface hello packet was received
• priority (number 1..255) : - priority of the neighbor router
• holdtime (time) : - how long entry will be held in neighbour list (configured in interface menu hello-holdtime)
• timeout (time) : - how much time left when entry will be dropped from list if no hello packets are received. Every time hello packet is received this entry will be refreshed.

bsr

Bootstrap router information

• zone-type () :
• bsr-address () :
• scope-zone () :
• bsr-priority () :
• local-address () :
• local-priority () :
• state () :
• timout () :
• sz-timout () :

mfc

Multicast forwarding cache - this section only provides information about current state of multicast cloud at given router, showing states of joins for multicast groups.

• group () : name of multicast group
• source () : source of multicast group data
• rp () : address of RP for that multicast group
• incoming-interface () : interface that is used to receive multicast data stream
• outgoing-interface () : interface that is used to transmit multicast data stream

joins

Group join list of all the group joins that are registered by PIM-SM

• group () :
• source () :
• rp () :
• upstream-interface-source () :
• upstream-interface-rp () :
• upstream-mrib-nexthop () :
• upstream-pim-nexthop () :
• join-state () :
• join-register-state () :
• timeout () :
• keepalive-timer () :
• i-am-designated-router () :
• local-receivers () :
• joined-rp () :
• joined-wc () :
• joined () :
• pruned () :
• prune-pending () :
• assert-winner () :
• assert-looser () :
• assert-winner-wc () :
• assert-looser-wc () :
• assert-tracking-wc () :
• could-assert-wc () :
• immediate-rp () :
• immediate-wc () :
• immediate-sg () :
• immediate-sg-rpt () :
• include-wc () :