Dell PowerConnect 5212 Specifications download pdf (Page 72)

The following table summarizes the equivalent CLI command for items in the SNMP/IP Filtering page.



Example



Console(config)#snmp ip filter 10.1.2.3 255.255.255.255



Console(config)#

Multicast Support

Multicasting is used to support real-time programs such as video conferencing or streaming audio. A multicast server does not have to establish a separate

connection with each client. Instead, it broadcasts its service to the network and to any hosts that are supposed to receive the multicast register with their

local multicast routers/switches. This approach reduces the network overhead required by a multicast server. However, each time the broadcast traffic passes

through a multicast router/switch, the traffic must be carefully queried to ensure that only hosts that subscribe to the service receive the broadcast.

The switch uses the Internet Group Management Protocol (IGMP) to determine if any attached hosts are supposed to receive a specific IP multicast service.

IGMP runs between hosts and their adjacent multicast routers/switches. IGMP is a multicast host registration protocol that allows any host to inform its local

router that the host is supposed to receive transmissions addressed to a specific multicast group.

IGMP requires one device to act as the querier on each LAN subnetwork. The querier is the IGMP-enabled device that periodically sends query messages to all

hosts asking them if they want to receive multicast traffic. Hosts respond with report messages, indicating to multicast groups that they wish to join or to

which group they already belong. The querier then propagates the service requests on to any adjacent multicast switch/router to ensure that it continues to

receive the multicast services.

IGMP-enabled devices prune multicast traffic on the network by passively snooping on IGMP report messages passing through their ports. The devices monitor

host report messages, pick out the multicast group registration information, and then configure filters accordingly so that multicast traffic for particular groups

is not forwarded on to ports that do not require it. This capability significantly reduces the multicast traffic on the network.

The Multicast Support page contains links to the following pages:

l IGMP Setting

l IGMP Member Port Table

l Multicast Router Port Settings

IGMP Setting

With IGMP Snooping, you can configure the switch to forward multicast traffic intelligently. Based on the IGMP query and report messages, the switch

forwards traffic only to the ports that request multicast traffic. This querying prevents the switch from broadcasting the traffic to all ports and possibly

disrupting network performance.



On the IGMP Setting page, the following options are available:

l IGMP Status — Enables IGMP. When IGMP is enabled, the switch monitors network traffic to determine which hosts are supposed to receive multicast

traffic.

l Act as IGMP Querier — Enables the switch as Querier. When Querier is enabled, the switch can serve as the Querier, which is responsible for asking

hosts if they are supposed to receive multicast traffic.

l IGMP Query Count (2–10) — Sets the maximum number of queries issued for which there has been no response before the switch takes action to

solicit reports. (The range is 2 to 10.)

l IGMP Query Interval (60–125) — Sets the frequency at which the switch sends IGMP host-query messages. (The range is 60 to 125.)

l IGMP Report Delay (5–30) — Sets the time (in seconds) between receiving an IGMP Report for an IP multicast address on a port before the switch

sends an IGMP Query out of that port and removes the entry from its list. (The range is 5 to 30.)

l IGMP Query Timeout (300–500) — Sets the time the switch waits after the previous querier has stopped querying before it takes over as the

querier. (The range is 300 to 500.)

l IGMP Version — Sets the protocol version for compatibility with other devices on the network (1 or 2).

To save any changes you make in this page, click Apply Changes. If you don't want to save the changes, click Refresh.



Command

Usage

snmp ip filter ip_address subnet_mask

Sets IP addresses of clients allowed to management access to the switch via SNMP.

Use the no form of this command to remove an IP address.

NOTE: IGMP requires a router that learns about the presence of multicast groups on its subnets and keeps track of group membership.

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Dell PowerConnect 5212 Specifications Page 72

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