
212
C
HAPTER
11: IP M
ULTICAST
F
ILTERING
WITH
IGMP
Routers and switches both construct filters on ports that do not require
group traffic to be forwarded. On each device, one group’s traffic may be
forwarded to one set of ports and another group’s traffic may be
forwarded to a different set of ports.
Tracking Group Member Locations
The ability to detect the location of group members is a product of two
IGMP functions — querying and snooping — working together to
construct individual delivery trees for each IP multicast group.
In each subnetwork or broadcast domain (VLAN), all switches and routers
perform snooping (for their own connections), but only one of the
devices needs to perform the querying. If there are multiple devices
(routers and switches) in the subnetwork or broadcast domain that
support querying, the one with the lowest IP address is elected as the
querier
.
The querier periodically sends a
query message
to all hosts on the
subnetwork or broadcast domain and requests that they reply with the IP
multicast groups for which they want to receive traffic.
A host responds to a query by sending an
IGMP report.
The querier as
well as IGMP-capable devices between hosts and the querier
snoop
on
the report’s content to track which hosts (and their associated ports)
belong to which groups.
If, after a certain period of time, a router or switch does not receive
responses from any host on a given interface or port for a particular IP
multicast group, the router or switch
prunes
the interface or port from
the delivery tree to conserve network bandwidth.
If a switch that has downstream group members, an upstream router and
upstream sources is elected as the querier, the switch must forward host
reports to the upstream router to maintain the flow of IP multicast traffic
to the switch.
Содержание 4007
Страница 1: ...http www 3com com Switch 4007 Implementation Guide Release 3 0 5 Part No 10013673 Published May 2000 ...
Страница 36: ...36 ABOUT THIS GUIDE ...
Страница 37: ...I UNDERSTANDING YOUR SWITCH 4007 SYSTEM Chapter 1 Configuration Overview ...
Страница 38: ......
Страница 50: ...50 CHAPTER 1 CONFIGURATION OVERVIEW ...
Страница 52: ......
Страница 70: ...70 CHAPTER 3 INSTALLING MANAGEMENT MODULES ...
Страница 110: ...110 CHAPTER 4 CONFIGURING AND USING EME OPTIONS ...
Страница 130: ...130 CHAPTER 5 MANAGING THE CHASSIS POWER AND TEMPERATURE ...
Страница 222: ...222 CHAPTER 11 IP MULTICAST FILTERING WITH IGMP ...
Страница 240: ...240 CHAPTER 13 RESILIENT LINKS ...
Страница 304: ...304 CHAPTER 14 VIRTUAL LANS VLANS ...
Страница 350: ...350 CHAPTER 15 PACKET FILTERING ...
Страница 506: ...506 CHAPTER 19 OPEN SHORTEST PATH FIRST OSPF ROUTING ...
Страница 534: ...534 CHAPTER 20 IPX ROUTING ...
Страница 612: ...612 CHAPTER 22 QOS AND RSVP ...
Страница 656: ...656 CHAPTER 23 DEVICE MONITORING ...
Страница 657: ...IV REFERENCE Appendix A Technical Support Index ...
Страница 658: ......
Страница 664: ......