Netgear CSM4532 Software Administration Manual - Page 89

Join/Leave PDUs.

Page 89 highlights

When a VLAN is configured with SDVoE enabled, the following operation happens: • All unknown data multicast will be blocked by default on VLAN 1. • IGMP Snooping enabled by default for VLAN 1. • IGMP snooping Fast-leave operation automatic: o Fast-leave is enabled on spanning-tree edge ports where encoders and decoders are connected. o Fast-leave is disabled on spanning-tree non-edge ports when connected to another switch. • Flooding of IGMP (v1/v2) Join and Leave messages in a Switch. Note: This function is disable by default, user need to enable manually. o As per RFC 4541 all IGMP Join and Leave PDUs are processed by IGMP Snooping application and also forwarded through the mrouter port(s). Non-mrouter ports don't get to receive IGMP Join/Leave PDUs. o The intention of this part of the enhancement is to have a controlled way at a system level to flood an IGMP Join/Leave PDU received on a downstream port (from a host) to all other ports, given the boundary of the associated VLAN. o In a deployment where switches are connected in a star-like topology with one switch or stack connecting all others, this enables creating forwarding table entries across multiple switches and enables an Rx device on a switch to receive multicast data stream transmitted by a Tx device connected to another switch. • Mrouter port to block all known (downstream hosts) and unknown Multicast data streams. o As per RFC 4541, a designated mrouter port (either detected dynamically or configured by user) forwards the following to the upstream router: 1. All IGMP (v1/v2/v3) PDUs. 2. All unknown Multicast streams - streams for which the switch has not received IGMP membership. 3. All known Multicast streams - streams for which switch has received IGMP membership (from the hosts connected to it) and has its HW MFDB (Multicast Forwarding Data Base) table populated. o This enhancement aims at blocking the 2nd and 3rd points, only leaving 1st. Therefore, barring IGMP PDU forwarding, the mrouter port is to behave as any other host port. It forwards multicast data stream only if an IGMP membership (v1/v2) has been received through this port. • Hardware forwarding of specific Multicast addresses. o The multicast addresses in the range 224.0.0.1 to 224.0.0.255 are considered as "Reserved" multicast addresses and are processed or forwarded by CPU, i.e., SW control plane. This enhancement is aimed to let a specific multicast addresses from this range and a few others to be forwarded by HW (ASICs) instead. NETGEAR M4500 Series Switches Software Administration Manual 89

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NETGEAR M4500 Series Switches Software Administration Manual
89
When a VLAN is configured with SDVoE enabled, the following operation happens:
All unknown data multicast will be blocked by default on VLAN 1.
IGMP Snooping enabled by default for VLAN 1.
IGMP snooping Fast-leave operation automatic:
o
Fast-leave is enabled on spanning-tree edge ports where encoders and decoders are connected.
o
Fast-leave is disabled on spanning-tree non-edge ports when connected to another switch.
Flooding of IGMP (v1/v2) Join and Leave messages in a Switch.
Note:
This function is disable by default, user need to enable manually.
o
As per RFC 4541 all IGMP Join and Leave PDUs are processed by IGMP Snooping application and
also forwarded through the mrouter port(s). Non-mrouter ports don’t get to receive IGMP
Join/Leave PDUs.
o
The intention of this part of the enhancement is to have a controlled way at a system level to
flood an IGMP Join/Leave PDU received on a downstream port (from a host) to all other ports,
given the boundary of the associated VLAN.
o
In a deployment where switches are connected in a star-like topology with one switch or stack
connecting all others, this enables creating forwarding table entries across multiple switches and
enables an Rx device on a switch to receive multicast data stream transmitted by a Tx device
connected to another switch.
Mrouter port to block all known (downstream hosts) and unknown Multicast data streams.
o
As per RFC 4541, a designated mrouter port (either detected dynamically or configured by user)
forwards the following to the upstream router:
1.
All IGMP (v1/v2/v3) PDUs.
2.
All unknown Multicast streams – streams for which the switch has not received IGMP
membership.
3.
All known Multicast streams – streams for which switch has received IGMP membership (from
the hosts connected to it) and has its HW MFDB (Multicast Forwarding Data Base) table
populated.
o
This enhancement aims at blocking the 2nd and 3rd points, only leaving 1st. Therefore, barring
IGMP PDU forwarding, the mrouter port is to behave as any other host port. It forwards multicast
data stream only if an IGMP membership (v1/v2) has been received through this port.
Hardware forwarding of specific Multicast addresses.
o
The multicast addresses in the range 224.0.0.1 to 224.0.0.255 are considered as “Reserved”
multicast addresses and are processed or forwarded by CPU, i.e., SW control plane. This
enhancement is aimed to let a specific multicast addresses from this range and a few others to be
forwarded by HW (ASICs) instead.