IES-1248-71/73 User’s Guide
167
C
H A P T E R
20
IGMP
This chapter describes the
IGMP
screens.
20.1 IGMP
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender to 1
recipient) or Broadcast (1 sender to everybody on the network). Multicast delivers IP packets
to just a group of hosts on the network.
IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to establish
membership in a multicast group - it is not used to carry user data. See RFC 1112 and RFC
2236 for information on IGMP versions 1 and 2, respectively.
20.2 IP Multicast Addresses
In IPv4, a multicast address allows a device to send packets to a specific group of hosts
(multicast group) in a different sub-network. A multicast IP address represents a traffic
receiving group, not individual receiving devices. IP addresses in the Class D range (224.0.0.0
to 239.255.255.255) are used for IP multicasting. Certain IP multicast numbers are reserved by
IANA for special purposes (see the IANA web site for more information).
20.2.1 IGMP Snooping
A layer-2 switch can passively snoop on IGMP Query, Report and Leave (IGMP version 2)
packets transferred between IP multicast routers/switches and IP multicast hosts to learn the IP
multicast group membership. It checks IGMP packets passing through it, picks out the group
registration information, and configures multicasting accordingly. IGMP snooping allows the
IES-1248 to learn multicast groups without you having to manually configure them.
The IES-1248 forwards multicast traffic destined for multicast groups (that it has learned from
IGMP snooping or that you have manually configured) to ports that are members of that
group. The IES-1248 discards multicast traffic destined for multicast groups that it does not
know. IGMP snooping generates no additional network traffic, allowing you to significantly
reduce multicast traffic passing through your device.
20.2.2 IGMP Proxy
To allow better network performance, you can use IGMP proxy instead of a multicast routing
protocol in a simple tree network topology.
Summary of Contents for IES-1248-71
Page 2: ......
Page 8: ...Safety Warnings IES 1248 71 73 User s Guide 8 ...
Page 38: ...List of Tables IES 1248 71 73 User s Guide 38 ...
Page 40: ...40 ...
Page 52: ...Chapter 2 Hardware Installation IES 1248 71 73 User s Guide 52 ...
Page 60: ...Chapter 3 Front Panel Connections IES 1248 71 73 User s Guide 60 ...
Page 68: ...Chapter 4 MDF Connections IES 1248 71 73 User s Guide 68 ...
Page 74: ...74 ...
Page 81: ...Chapter 7 Introducing the Web Configurator IES 1248 71 73 User s Guide 81 Figure 30 Logout ...
Page 82: ...Chapter 7 Introducing the Web Configurator IES 1248 71 73 User s Guide 82 ...
Page 110: ...Chapter 12 User Account IES 1248 71 73 User s Guide 110 ...
Page 116: ...Chapter 13 Switch Setup IES 1248 71 73 User s Guide 116 ...
Page 118: ...Chapter 14 IP Setup IES 1248 71 73 User s Guide 118 ...
Page 150: ...Chapter 17 xDSL Profiles Setup IES 1248 71 73 User s Guide 150 ...
Page 158: ...158 ...
Page 166: ...Chapter 19 VLAN IES 1248 71 73 User s Guide 166 ...
Page 184: ...Chapter 22 Multicast VLAN IES 1248 71 73 User s Guide 184 ...
Page 216: ...Chapter 30 2684 Routed Mode IES 1248 71 73 User s Guide 216 ...
Page 222: ...Chapter 31 PPPoA to PPPoE IES 1248 71 73 User s Guide 222 ...
Page 226: ...Chapter 32 DSCP IES 1248 71 73 User s Guide 226 ...
Page 240: ...Chapter 36 Syslog IES 1248 71 73 User s Guide 240 ...
Page 248: ...Chapter 37 Access Control IES 1248 71 73 User s Guide 248 ...
Page 250: ...250 ...
Page 259: ...Chapter 39 Alarm IES 1248 71 73 User s Guide 259 ...
Page 260: ...Chapter 39 Alarm IES 1248 71 73 User s Guide 260 ...
Page 276: ...276 ...
Page 296: ...Chapter 44 Commands IES 1248 71 73 User s Guide 296 ...
Page 304: ...Chapter 45 Command Examples IES 1248 71 73 User s Guide 304 ...
Page 320: ...Chapter 47 DHCP Commands IES 1248 71 73 User s Guide 320 ...
Page 328: ...Chapter 48 IEEE 802 1Q Tagged VLAN Commands IES 1248 71 73 User s Guide 328 ...
Page 334: ...Chapter 49 MAC Commands IES 1248 71 73 User s Guide 334 ...
Page 348: ...Chapter 50 IGMP Commands IES 1248 71 73 User s Guide 348 ...
Page 352: ...Chapter 51 Packet Filter Commands IES 1248 71 73 User s Guide 352 ...
Page 362: ...Chapter 53 Firmware and Configuration File Maintenance IES 1248 71 73 User s Guide 362 ...
Page 394: ...Chapter 55 ADSL Commands IES 1248 71 73 User s Guide 394 ...
Page 418: ...Chapter 56 Virtual Channel Management IES 1248 71 73 User s Guide 418 ...
Page 424: ...Chapter 57 ACL Commands IES 1248 71 73 User s Guide 424 ...
Page 436: ...Chapter 58 Troubleshooting IES 1248 71 73 User s Guide 436 ...
Page 437: ...437 PART VI Appendices and Index Product Specifications 439 Legal Information 449 Index 457 ...
Page 438: ...438 ...
Page 448: ...Appendix B Removing and Installing a Fuse IES 1248 71 73 User s Guide 448 ...
Page 452: ...Appendix C Legal Information IES 1248 71 73 User s Guide 452 ...