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245 lines
7.8 KiB
ReStructuredText
245 lines
7.8 KiB
ReStructuredText
.. _multicast:
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#########
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Multicast
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#########
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VyOS facilitates IP Multicast by supporting **PIM Sparse Mode**,
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**IGMP** and **IGMP-Proxy**.
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************
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PIM and IGMP
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************
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PIM (Protocol Independent Multicast) must be configured in every
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interface of every participating router. Every router must also have the
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location of the Rendevouz Point manually configured. Then,
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unidirectional shared trees rooted at the Rendevouz Point will
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automatically be built for multicast distribution.
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Traffic from multicast sources will go to the Rendezvous Point, and
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receivers will pull it from a shared tree using IGMP (Internet Group
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Management Protocol).
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Multicast receivers will talk IGMP to their local router, so, besides
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having PIM configured in every router, IGMP must also be configured in
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any router where there could be a multicast receiver locally connected.
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VyOS supports both IGMP version 2 and version 3 (which allows
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source-specific multicast).
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Example
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=======
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In the following example we can see a basic multicast setup:
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.. image:: /_static/images/multicast-basic.png
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:width: 90%
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:align: center
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:alt: Network Topology Diagram
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**Router 1**
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.. code-block:: none
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set interfaces ethernet eth2 address '172.16.0.2/24'
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set interfaces ethernet eth1 address '100.64.0.1/24'
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set protocols ospf area 0 network '172.16.0.0/24'
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set protocols ospf area 0 network '100.64.0.0/24'
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set protocols igmp interface eth1
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set protocols pim interface eth1
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set protocols pim interface eth2
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set protocols pim rp address 172.16.255.1 group '224.0.0.0/4'
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**Router 3**
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.. code-block:: none
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set interfaces dummy dum0 address '172.16.255.1/24'
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set interfaces ethernet eth0 address '172.16.0.1/24'
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set interfaces ethernet eth1 address '172.16.1.1/24'
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set protocols ospf area 0 network '172.16.0.0/24'
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set protocols ospf area 0 network '172.16.255.0/24'
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set protocols ospf area 0 network '172.16.1.0/24'
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set protocols pim interface dum0
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set protocols pim interface eth0
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set protocols pim interface eth1
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set protocols pim rp address 172.16.255.1 group '224.0.0.0/4'
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**Router 2**
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.. code-block:: none
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set interfaces ethernet eth1 address '10.0.0.1/24'
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set interfaces ethernet eth2 address '172.16.1.2/24'
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set protocols ospf area 0 network '10.0.0.0/24'
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set protocols ospf area 0 network '172.16.1.0/24'
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set protocols pim interface eth1
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set protocols pim interface eth2
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set protocols pim rp address 172.16.255.1 group '224.0.0.0/4'
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Basic commands
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==============
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These are the commands for a basic setup.
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.. cfgcmd:: set protocols pim interface <interface-name>
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Use this command to enable PIM in the selected interface so that it
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can communicate with PIM neighbors.
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.. cfgcmd:: set protocols pim rp address <address> group <multicast-address/mask-bits>
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Use this comand to manually configure a Rendevouz Point for PIM so
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that join messages can be sent there. Set the Rendevouz Point address
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and the matching prefix of group ranges covered. These values must
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be shared with every router participating in the PIM network.
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.. cfgcmd:: set protocols igmp interface eth1
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Use this command to configure an interface with IGMP so that PIM can
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receive IGMP reports and query on the selected interface. By defaul
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IGMP version 3 will be used.
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Tuning commands
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===============
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You can also tune multicast with the following commands.
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.. cfgcmd:: set protocols pim interface <interface> dr-priority <value>
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Use this PIM command in the selected interface to set the priority
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(1-4294967295) you want to influence in the election of a node to
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become the Designated Router for a LAN segment. The default priority
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is 1, set a higher value to give the router more preference in the
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DR election process.
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.. cfgcmd:: set protocols pim int <interface> hello <seconds>
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Use this command to configure the PIM hello interval in seconds
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(1-180) for the selected interface.
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.. cfgcmd:: set protocols pim rp keep-alive-timer <seconds>
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Use this PIM command to modify the the time out value (31-60000
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seconds) for an `(S,G) <https://tools.ietf.org/html/rfc7761#section-4.1>`_
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flow. 31 seconds is chosen for a lower bound as some hardware
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platforms cannot see data flowing in better than 30 second chunks.
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.. cfgcmd:: set protocols igmp interface <interface> join <multicast-address> source <IP-address>
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Use this command to allow the selected interface join a multicast
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group defining the multicast address you want to join and the source
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IP address too.
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.. cfgcmd:: set protocols igmp interface <interface query-interval <seconds>
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Use this command to configure in the selected interface the IGMP
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host query interval (1-1800) in seconds that PIM will use.
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.. cfgcmd:: set protocols igmp interface <interface query-max-response-time <deciseconds>
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Use this command to configure in the selected interface the IGMP
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query response timeout value (10-250) in deciseconds. If a report is
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not returned in the specified time, it will be asumed the `(S,G) or
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(*,G) state <https://tools.ietf.org/html/rfc7761#section-4.1>`_ has
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timed out.
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.. cfgcmd:: set protocols igmp interface <interface> version <version-number>
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Use this command to define in the selected interface whether you
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choose IGMP version 2 or 3. The default value is 3.
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**********
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IGMP Proxy
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**********
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:abbr:`IGMP (Internet Group Management Protocol)` proxy sends IGMP host messages
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on behalf of a connected client. The configuration must define one, and only one
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upstream interface, and one or more downstream interfaces.
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Configuration
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=============
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.. cfgcmd:: set protocols igmp-proxy interface <interface> role <upstream | downstream>
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* **upstream:** The upstream network interface is the outgoing interface
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which is responsible for communicating to available multicast data sources.
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There can only be one upstream interface.
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* **downstream:** Downstream network interfaces are the distribution
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interfaces to the destination networks, where multicast clients can join
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groups and receive multicast data. One or more downstream interfaces must
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be configured.
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.. cfgcmd:: set protocols igmp-proxy interface <interface> alt-subnet <network>
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Defines alternate sources for multicasting and IGMP data. The network address
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must be on the following format 'a.b.c.d/n'. By default the router will
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accept data from sources on the same network as configured on an interface.
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If the multicast source lies on a remote network, one must define from where
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traffic should be accepted.
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This is especially useful for the upstream interface, since the source for
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multicast traffic is often from a remote location.
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This option can be supplied multiple times.
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.. cfgcmd:: set protocols igmp-proxy disable-quickleave
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Disables quickleave mode. In this mode the daemon will not send a Leave IGMP
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message upstream as soon as it receives a Leave message for any downstream
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interface. The daemon will not ask for Membership reports on the downstream
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interfaces, and if a report is received the group is not joined again
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upstream.
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If it's vital that the daemon should act exactly as a real multicast client
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on the upstream interface, this function should be enabled.
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Enabling this function increases the risk of bandwidth saturation.
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.. cfgcmd:: set protocols igmp-proxy disable
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Disable this service.
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Example
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-------
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Interface `eth1` LAN is behind NAT. In order to subscribe `10.0.0.0/23` subnet
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multicast which is in `eth0` WAN we need to configure igmp-proxy.
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.. code-block:: none
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set protocols igmp-proxy interface eth0 role upstream
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set protocols igmp-proxy interface eth0 alt-subnet 10.0.0.0/23
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set protocols igmp-proxy interface eth1 role downstream
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Operation
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=========
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.. opcmd:: restart igmp-proxy
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Restart the IGMP proxy process.
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