D-Link DES-3528 - xStack Switch - Stackable, Руководство пользователя, Страница: 108 / 322

xStack
®
DES-3528/DES-3552 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual
107
From Port / To Port
Check the corresponding boxes for the port(s) to filter control packets.
State
Use the drop-down menu to enable or disable the filtering function.
IGMP Query
Tick the check box to set IGMP query packets as the control packets.
DVMRP
Tick the check box to set DVMRP query packets as the control packets.
PIM
Tick the check box to set PIM query packets as the control packets.
All
Tick the check box to set all above query packets as the control packets.
To enable the function, enter the information and click
Apply
.
MLD Snooping Settings
Multicast Listener Discovery (MLD) Snooping is an IPv6 function used similarly to IGMP snooping in IPv4. It is used to
discover ports on a VLAN that are requesting multicast data. Instead of flooding all ports on a selected VLAN with
multicast traffic, MLD snooping will only forward multicast data to ports that wish to receive this data through the use
of queries and reports produced by the requesting ports and the source of the multicast traffic.
MLD snooping is accomplished through the examination of the layer 3 part of an MLD control packet transferred
between end nodes and a MLD router. When the Switch discovers that this end node is requesting multicast traffic, it
adds the port directly attached to it into the correct IPv6 multicast table, and begins the process of forwarding multicast
traffic to that port. This entry in the multicast routing table records the port, the VLAN ID and the associated IPv6
multicast group address and then considers this port to be a active listening port. The active listening ports are the
only ones to receive multicast group data.
MLD Control Messages
Three types of messages are transferred between devices using MLD snooping. These three messages are all
defined by three ICMPv6 packet headers, labeled 130, 131 and 132.
1.
Multicast Listener Query
– Similar to the IGMPv2 Host Membership Query for IPv4, and labeled as 130 in
the ICMPv6 packet header, this message is sent by the router to ask if any link is requesting multicast data.
There are two types of MLD query messages emitted by the router. The General Query is used to advertise all
multicast addresses that are ready to send multicast data to all listening ports, and the Multicast Specific
query, which advertises a specific multicast address that is ready. These two types of messages are
distinguished by a multicast destination address located in the IPv6 header and a multicast address in the
Multicast Listener Query Message.
2.
Multicast Listener Report
– Comparable to the Host Membership Report in IGMPv2, and labeled as 131 in
the ICMP packet header, this message is sent by the listening host to the Switch stating that it is interested in
receiving multicast data from a multicast address in response to the Multicast Listener Query message.
3.
Multicast Listener Done
– Akin to the Leave Group Message in IGMPv2, and labeled as 132 in the ICMPv6
packet header, this message is sent by the multicast listening host stating that it is no longer interested in
receiving multicast data from a specific multicast group address, therefore stating that it is “done” with the
multicast data from this address. Once this message is received by the Switch, it will no longer forward
multicast traffic from a specific multicast group address to this listening host.
MLD Snooping Settings
This table is used to enable MLD Snooping on the Switch and to configure the settings for MLD snooping, click
L2
Features > MLD Snooping > MLD Snooping Settings
, which will open the following window.