Multimedia Traffic Control with IP Multicast (IGMP)
How IGMP Operates
Operation With or Without IP Addressing
You can configure IGMP on VLANs that do not have IP addressing. The benefit of IGMP without IP addressing is a reduction in the number of IP addresses you have to use and configure. This can be significant in a network with a large number of VLANs. The limitation on IGMP without IP addressing is that the switch cannot become Querier on any VLANs for which it has no IP address— so the network administrator must ensure that another IGMP device will act as Querier. It is also advisable to have an additional IGMP device available as a backup Querier. See the following table.
TableIGMP Function Available With IP Addressing | Available | Operating Differences | |
Configured on the VLAN | Without IP | Without an IP Address | |
| Addressing? |
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Forward multicast group traffic to any port on | Yes | None | |
the VLAN that has received a join request for |
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that multicast group. |
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Forward join requests (reports) to the Querier. | Yes | None | |
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Configure individual ports in the VLAN to Auto | Yes | None | |
(the default)/Blocked, or Forward. |
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Configure IGMP traffic forwarding to normal or | Yes | None | |
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Yes | Requires that another IGMP device in the VLAN has an IP | ||
IGMP client on a port in the VLAN leaves the |
| address and can operate as Querier. This can be a | |
group. |
| multicast router or another switch configured for IGMP | |
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| operation. (ProCurve recommends that the VLAN also | |
Support | Yes | ||
include a device operating as a backup Querier in case | |||
| the device operating as the primary Querier fails for any | ||
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| reason. | |
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Support automatic Querier election. | No | Querier operation not available. | |
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Operate as the Querier. | No | Querier operation not available. | |
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Available as a backup Querier. | No | Querier operation not available. | |
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