Implementing IBM System Networking 10Gb Ethernet Switches

Chapter 2. IBM System Networking Switch 10Gb Ethernet switch features 69

IGMP Querier

IGMP Querier allows the switch to perform the multicast router (Mrouter) role and provide

Mrouter discovery when the network or virtual LAN (VLAN) does not have a router.

When IGMP Querier is enabled on a VLAN, the switch acts as an IGMP querier in a Layer 2

network environment. The IGMP querier periodically broadcasts IGMP Queries and listens for

hosts to respond with IGMP Reports indicating their IGMP group memberships. If multiple

Mrouters exist on a network, the Mrouters elect one as the querier, which performs all

periodic membership queries. The election process can be based on IPv4 address or

MAC address.

IGMP Relay

IBM System Networking switch can act as an IGMP Relay (or IGMP Proxy) device that relays

IGMP multicast messages and traffic between a Mrouter and endpoints. IGMP Relay allows a

switch to participate in network multicasts with no configuration of the various multicast

routing protocols, so you can deploy it in the network with minimal effort.

To an IGMP host connected to IBM System Networking switch, IGMP Relay appears to be an

IGMP multicast router (Mrouter). IGMP Relay sends Membership Queries to hosts, which

respond by sending an IGMP response message. A host can also send an unsolicited Join

message to the IGMP Relay.

To a multicast router, IGMP Relay appears as a host. The Mrouter sends IGMP host queries

to IGMP Relay, and IGMP Relay responds by forwarding IGMP host reports and unsolicited

join messages from its attached hosts.

IGMP Relay also forwards multicast traffic between the Mrouter and endpoints, similar to

IGMP Snooping.

You can configure up to two Mrouters to use with IGMP Relay. One Mrouter acts as the

primary Mrouter, and one is the backup Mrouter. The switch uses health checks to select the

primary Mrouter.

IGMP Filtering

With IGMP Filtering, you can allow or deny a port to send and receive multicast traffic to

certain multicast groups. Unauthorized users are restricted from streaming multicast traffic

across the network.

If access to a multicast group is denied, IGMP Membership Reports from the port are

dropped, and the port is not allowed to receive IPv4 multicast traffic from that group. If access

to the multicast group is allowed, Membership Reports from the port are forwarded for

normal processing.

To configure IGMP Filtering, you must globally enable IGMP filtering, define an IGMP filter,

assign the filter to a port, and enable IGMP Filtering on the port. To define an IGMP filter, you

must configure a range of IPv4 Multicast groups, choose whether the filter allows or denies

multicast traffic for groups within the range, and enable the filter.

2.4.2 Protocol Independent Multicast

Protocol Independent Multicast (PIM) is designed for efficiently routing multicast traffic across

one or more IPv4 domains. This protocol has benefits for application such as IP television,

collaboration, education, and software delivery, where a single source must deliver content (a

multicast) to a group of receivers that span both wide-area and inter-domain networks.