D-Link DES-3350SR, Руководство пользователя

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D-Link DES-3350SR Standalone Layer 3 Switch
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The Robustness Variable field allows IGMP to be ‘tuned’ for sub-networks that are expected to lose many packets. A high value
(max. 255) for the robustness variable will help compensate for ‘lossy’ sub-networks. A low value (min. 2) should be used for less
‘lossy’ sub-networks.
The following fields can be set:
Parameters Description
Interface Name
Displays the name of the IP interface that
is to be configured for IGMP. This must be
a previously configured IP interface.
IP Address
Displays the IP address corresponding to
the IP interface name above.
Version
Enter the IGMP version (1, 2 or 3) that will
be used to interpret IGMP queries on the
interface.
Query Interval
Allows the entry of a value between 1 and
31744 seconds, with a default of 125
seconds. This specifies the length of time
between sending IGMP queries.
Max Response Time
Sets the maximum amount of time allowed
before sending an IGMP response report.
A value between 1 and 25 seconds can be
entered, with a default of 10 seconds.
Robustness Variable
A tuning variable to allow for subnetworks
that are expected to lose a large number of
packets. A value between 2 and 255 can
be entered, with larger values being
specified for subnetworks that are
expected to lose larger numbers of
packets.
Last Member Query
Interval
Specifies the maximum amount of time
between group-specific query messages,
including those sent in response to leave
group messages. A value between 1 and
25. The default is
1 second.
State
This field can be toggled between Enabled
and Disabled and enables or disables
IGMP for the IP interface. The default is
Disabled .
Click Apply to implement changes made.
DVMRP Interface Settings
The Distance Vector Multicast Routing Protocol ( DVMRP ) is a hop-based method of building multicast delivery trees from
multicast sources to all nodes of a network. Because the delivery trees are ‘pruned’ and ‘shortest path’, DVMRP is relatively
efficient. Because multicast group membership information is forwarded by a distance-vector algorithm, propagation is slow.
DVMRP is optimized for high delay (high latency) relatively low bandwidth networks, and can be considered as a ‘best-effort’
multicasting protocol.
DVMRP resembles the Routing Information Protocol (RIP), but is extended for multicast delivery. DVMRP builds a routing table
to calculate ‘shortest paths’ back to the source of a multicast message, but defines a ‘route cost’ (similar to the hop count in RIP) as
a relative number that represents the real cost of using this route in the construction of a multicast delivery tree to be ‘pruned’ -
once the delivery tree has been established.
When a sender initiates a multicast, DVMRP initially assumes that all users on the network will want to receive the multicast
message. When an adjacent router receives the message, it checks its unicast routing table to determine the interface that gives the
shortest path (lowest cost) back to the source. If the multicast was received over the shortest path, then the adjacent router enters
the information into its tables and forwards the message. If the message is not received on the shortest path back to the source, the
message is dropped.
Route cost is a relative number that is used by DVMRP to calculate which branches of a multicast delivery tree should be ‘pruned’.
The ‘cost’ is relative to other costs assigned to other DVMRP routes throughout the network.
The higher the route cost, the lower the probability that the current route will be chosen to be an active branch of the multicast
delivery tree (not ‘pruned’) - if there is an alternative route.
To enable DVMRP globally on the Switch, click Configuration > Layer 3 IP Networking > IP Multicast Routing Protocol >
DVMRP Interface Settings . This will give the user access to the following screen: