Aztech ASX6600 Instructions for use

HPE FlexNetwork 5120 SI Switch Series
IP Multicast
Configuration Guide
Part number: 5998-8495
Software version: Release 1516
Document version: 6W100-20151125

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Contents
Multicast overview···························································································1
Introduction to multicast·····································································································································1
Information transmission techniques··········································································································1
Multicast features·······································································································································3
Common notations in multicast··················································································································4
Advantages and applications of multicast··································································································4
Multicast models ················································································································································4
Multicast architecture·········································································································································5
Multicast addresses ···································································································································5
Multicast protocols ·····································································································································9
Multicast packet forwarding mechanism··········································································································11
IGMP snooping configuration········································································12
IGMP snooping overview·································································································································12
Principle of IGMP snooping······················································································································12
Basic concepts in IGMP snooping ···········································································································13
How IGMP snooping works······················································································································14
IGMP snooping proxying··························································································································15
Protocols and standards ··························································································································16
IGMP snooping configuration task list··············································································································17
Configuring basic functions of IGMP snooping································································································18
Configuration prerequisites······················································································································18
Enabling IGMP snooping ·························································································································18
Configuring the version of IGMP snooping ······························································································18
Configuring static multicast MAC address entries····················································································19
Configuring IGMP snooping port functions ······································································································20
Configuration prerequisites······················································································································20
Configuring aging timers for dynamic ports······························································································20
Configuring static ports ····························································································································21
Configuring simulated joining···················································································································21
Configuring fast leave processing············································································································22
Disabling a port or a group of ports from changing into dynamic router ports ·········································23
Configuring IGMP snooping querier·················································································································23
Configuration prerequisites······················································································································23
Enabling IGMP snooping querier·············································································································24
Configuring IGMP queries and responses·······························································································24
Configuring source IP address of IGMP queries······················································································25
Configuring IGMP snooping proxying ··············································································································26
Configuration prerequisites······················································································································26
Enabling IGMP snooping proxying···········································································································26
Configuring a source IP address for the IGMP messages sent by the proxy···········································26
Configuring an IGMP snooping policy··············································································································26
Configuration prerequisites······················································································································26
Configuring a multicast group filter···········································································································27
Configuring multicast source port filtering································································································27
Configuring the function of dropping unknown multicast data··································································28
Configuring IGMP report suppression······································································································28
Configuring maximum multicast groups that a port can join ····································································29
Configuring multicast group replacement·································································································29
Configuring 802.1p precedence for IGMP messages··············································································30
Displaying and maintaining IGMP snooping ····································································································31
IGMP snooping configuration examples ··········································································································31
Group policy and simulated joining configuration example······································································31
Static port configuration example·············································································································34
IGMP snooping querier configuration example························································································37
IGMP snooping proxying configuration example······················································································39
Troubleshooting IGMP snooping configuration································································································41

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Switch fails in layer 2 multicast forwarding·······························································································41
Configured multicast group policy fails to take effect···············································································42
Multicast VLAN configuration········································································43
Introduction to multicast VLAN·························································································································43
Multicast VLAN configuration task list··············································································································44
Configuring multicast VLAN·····························································································································44
Configuration prerequisites······················································································································45
Configuring user port attributes················································································································45
Configuring multicast VLAN ports············································································································45
Displaying and maintaining multicast VLAN ····································································································46
Multicast VLAN configuration examples ··········································································································46
MLD snooping configuration·········································································50
MLD snooping overview···································································································································50
Introduction to MLD snooping··················································································································50
Basic concepts in MLD snooping·············································································································51
How MLD snooping works ·······················································································································52
MLD snooping proxying ···························································································································53
Protocols and standards ··························································································································54
MLD snooping configuration task list ···············································································································54
Configuring basic functions of MLD snooping··································································································56
Configuration prerequisites······················································································································56
Enabling MLD snooping···························································································································56
Configuring the version of MLD snooping································································································56
Configuring IPv6 static multicast MAC address entries ···········································································57
Configuring MLD snooping port functions········································································································58
Configuration prerequisites······················································································································58
Configuring aging timers for dynamic ports······························································································58
Configuring static ports ····························································································································59
Configuring simulated joining···················································································································59
Configuring fast leave processing············································································································60
Disabling a port or a group of ports from changing into dynamic router ports ·········································61
Configuring MLD snooping querier ··················································································································61
Configuration prerequisites······················································································································61
Enabling MLD snooping querier···············································································································62
Configuring MLD queries and responses·································································································62
Configuring source IPv6 addresses of MLD queries················································································63
Configuring MLD snooping proxying················································································································64
Configuration prerequisites······················································································································64
Enabling MLD snooping proxying ············································································································64
Configuring a source IPv6 address for the MLD messages sent by the proxy ········································64
Configuring an MLD snooping policy ···············································································································65
Configuration prerequisites······················································································································65
Configuring an IPv6 multicast group filter ································································································65
Configuring IPv6 multicast source port filtering························································································66
Configuring dropping unknown IPv6 multicast data·················································································66
Configuring MLD report suppression ·······································································································67
Configuring maximum multicast groups that a port can join ····································································67
Configuring IPv6 multicast group replacement ························································································68
Configuring 802.1p precedence for MLD messages················································································68
Displaying and maintaining MLD snooping······································································································69
MLD snooping configuration examples············································································································70
IPv6 group policy and simulated joining configuration example·······························································70
Static port configuration example·············································································································72
MLD snooping querier configuration example··························································································75
MLD snooping proxying configuration example·······················································································77
Troubleshooting MLD snooping·······················································································································80
Switch fails in layer 2 multicast forwarding·······························································································80
Configured IPv6 multicast group policy fails to take effect·······································································80

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IPv6 multicast VLAN configuration································································82
Introduction to IPv6 multicast VLAN ················································································································82
IPv6 multicast VLAN configuration task list······································································································83
Configuring IPv6 multicast VLAN·····················································································································83
Configuration prerequisites······················································································································84
Configuring user port attributes················································································································84
Configuring IPv6 multicast VLAN ports····································································································84
Displaying and maintaining IPv6 multicast VLAN ····························································································85
IPv6 multicast VLAN configuration examples ··································································································85
Document conventions and icons·································································89
Conventions·····················································································································································89
Network topology icons····································································································································90
Support and other resources ········································································91
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Multicast overview
NOTE:
This document focuses on the IP multicast technology and device operations. Unless otherwise
stated, the term multicast in this document refers to IP multicast.
Introduction to multicast
As a technique that coexists with unicast and broadcast, the multicast technique effectively
addresses the issue of point-to-multipoint data transmission. By enabling high-efficiency
point-to-multipoint data transmission over a network, multicast greatly saves network bandwidth and
reduces network load.
The multicast technology enables a network operator to easily provide new value-added services,
such as live webcasting, web TV, distance learning, telemedicine, web radio, real-time video
conferencing, and other bandwidth-critical and time-critical information services.
Information transmission techniques
Unicast
In unicast transmission, the information source must send a separate copy of information to each
host that needs the information.
Figure 1 Unicast transmission
In Figure 1, assume that Host B, Host D and Host E need the information. A separate transmission
channel must be established from the information source to each of these hosts.
In unicast transmission, the traffic transmitted over the network is proportional to the number of hosts
that need the information. If a large number of hosts need the information, the information source

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must send a copy of the same information to each of these hosts. Sending many copies can place a
tremendous pressure on the information source and the network bandwidth.
Unicast is not suitable for batch transmission of information.
Broadcast
In broadcast transmission, the information source sends information to all hosts on the subnet, even
if some hosts do not need the information.
Figure 2 Broadcast transmission
In Figure 2, assume that only Host B, Host D, and Host E need the information. If the information is
broadcast to the subnet, HostA and Host C also receive it. In addition to information security issues,
broadcasting to hosts that do not need the information causes traffic flooding on the same subnet.
Broadcast is disadvantageous in transmitting data to specific hosts. Moreover, broadcast
transmission is a significant waste of network resources.
Multicast
Unicast and broadcast techniques cannot provide point-to-multipoint data transmissions with the
minimum network consumption. Multicast transmission can solve this problem. When some hosts on
the network need multicast information, the information sender, or multicast source, sends only one
copy of the information. Multicast distribution trees are built through multicast routing protocols, and
the information is replicated only on nodes where the trees branch.

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Figure 3 Multicast transmission
In Figure 3, Host B, Host D and Host E are receivers of the information. They must join the multicast
group. The routers on the network duplicate and forward the information based on the distribution of
the group members. Finally, the information is correctly delivered to Host B, Host D, and Host E.
To summarize, multicast has the following advantages:
•Because multicast traffic flows to the farthest-possible node from the source before it is
replicated and distributed, an increase in the number of hosts will not increase the load of the
source and will not remarkably add to the usage of network resources.
•Because multicast data is sent only to the receivers that need it, multicast uses network
bandwidth reasonably and enhances network security. In addition, data broadcast is confined to
the same subnet, but multicast is not.
Multicast features
Multicast transmission has the following features:
•A multicast group is a multicast receiver set identified by an IP multicast address. Hosts join a
multicast group to become members of the multicast group, before they can receive the
multicast data addressed to that multicast group. Typically, a multicast source does not need to
join a multicast group.
•An information sender is called a "multicast source". A multicast source can send data to
multiple multicast groups at the same time, and multiple multicast sources can send data to the
same multicast group at the same time.
•All hosts that have joined amulticast group become members of the multicast group. The group
memberships are dynamic. Hosts can join or leave multicast groups at any time. Multicast
groups are not subject to geographic restrictions.
•Routers or Layer 3 switches that support Layer 3 multicast are called "multicast routers" or
"Layer 3 multicast devices". In addition to providing the multicast routing function, a multicast
router can manage multicast group memberships on stub subnets with attached group
members. A multicast router itself can be a multicast group member.
For a better understanding of the multicast concept, you can compare multicast transmission with
the transmission of TV programs.

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Table 1 Comparing TV transmission and multicast transmission
TV transmission Multicast transmission
A TV station transmits a TV program through a
channel. A multicast source sends multicast data to a multicast group.
A user tunes the TV set to the channel. A receiver joins the multicast group.
The user starts to watch the TV program
transmitted by the TV station via the channel. The receiver starts to receive the multicast data that the source is sending to the multicast group.
The user turns off the TV set or tunes to another
channel. The receiver leaves the multicast group or joins another group.
Common notations in multicast
The following notations are commonly used in multicast transmission:
•(*, G)—Indicates a rendezvous point tree (RPT), or a multicast packet that any multicast source
sends to multicast group G. Here the asterisk represents any multicast source, and "G"
represents a specific multicast group.
•(S, G)—Indicates a shortest path tree (SPT), or a multicast packet that multicast source S
sends to multicast group G. Here, "S" represents a specific multicast source, and "G"
represents a specific multicast group.
Advantages and applications of multicast
Advantages of multicast
The multicast technique has the following advantages:
•Enhanced efficiency—Reduces the CPU load of information source servers and network
devices.
•Optimal performance—Reduces redundant traffic.
•Distributed application—Enables point-to-multipoint applications at the price of minimum
network resources.
Applications of multicast
The multicast technique has the following applications:
•Multimedia and streaming applications, such as web TV, web radio, and real-time video/audio
conferencing
•Communication for training and cooperative operations, such as distance learning and
telemedicine
•Data warehouse and financial applications, such as stock quotes
•Any other point-to-multipoint applications for data distribution
Multicast models
Multicast models—any-source multicast (ASM), source-filtered multicast (SFM), and source-specific
multicast (SSM)—determines how the receivers treat the multicast sources.

5
ASM model
In the ASM model, any sender can send information to a multicast group as a multicast source, and
numbers of receivers can join a multicast group, which is identified by a group address, and can
obtain multicast information addressed to that multicast group. In this model, receivers do not
determine the positions of the multicast sources in advance. However, they can join or leave the
multicast group at any time.
SFM model
The SFM model is derived from the ASM model. To a sender, the two models appear to have the
same multicast membership architecture.
The SFM model functionally extends the ASM model. In the SFM model, the upper layer software
checks the source address of received multicast packets and permits or denies multicast traffic from
specific sources. Therefore, receivers can receive the multicast data from only part of the multicast
sources. To a receiver, not all multicast sources are valid because they are filtered.
SSM model
Users might be interested in the multicast data from only certain multicast sources. The SSM model
provides a transmission service that enables users to specify the multicast sources that they are
interested in at the client side.
The main difference between the SSM model and the ASM model is that in the SSM model,
receivers have already determined the locations of the multicast sources by some other means. In
addition, the SSM model uses a multicast address range that is different from that of the ASM/SFM
model, and dedicated multicast forwarding paths are established between receivers and the
specified multicast sources.
Multicast architecture
IP multicast addresses the following questions:
•Multicast addressing—Where should the multicast source transmit information to?
•Host registration—What receivers exist on the network?
•Multicast source discovery—Where is the multicast source that will provide data to the
receivers?
•Multicast routing—How should information be transmitted to the receivers?
IP multicast is an end-to-end service. The multicast architecture involves the following parts:
1. Addressing mechanism—A multicast source sends information to a group of receivers through
a multicast address.
2. Host registration—Receiver hosts can join and leave multicast groups dynamically. This
mechanism is the basis for group membership management.
3. Multicast routing—A multicast distribution tree—a forwarding path tree for multicast data on the
network—is constructed for delivering multicast data from a multicast source to receivers.
4. Multicast applications—A software system that supports multicast applications, such as video
conferencing, must be installed on multicast sources and receiver hosts. The TCP/IP stack
must support reception and transmission of multicast data.
Multicast addresses
Network-layer multicast addresses—namely, multicast IP addresses—enable communication
between multicast sources and multicast group members. In addition, a technique must be available
to map multicast IP addresses to link-layer multicast MAC addresses.