Westermo RedFox Series - Manual (Page 274)

Westermo OS Management Guide
Version 4.17.0-0
13.1.5 IGMP Snooping and VLANs
Switches use IGMP snooping for efficient distribution of IP(v4) multicast over the
LAN. With IGMP snooping enabled on a VLAN, IP multicast packets will only be
forwarded onto ports leading to a receiver of that IP multicast address, or to
ports assumed to lead to an IP multicast router.
With IGMP snooping disabled on a VLAN, multicast traffic will be forwarded on all
ports of that VLAN, i.e., it is treated similar to broadcast traffic.
By default IGMP snooping is enabled on each newly created VLAN. More informa-
tion on IGMP Snooping and IGMP Snooping settings is found in
chapter 18 .
13.1.6 Mapping VLANs to a CPU channel
A switch can have one or more channels to the switch CPU, each with a capacity of
100 Mbit/s or 1000 Mbit/s
3 . By default every new VLAN (with a network interface)
is mapped to CPU channel ”0” (zero).
On devices with multiple CPU channels increased routing performance may be
achieved by assigning different VLANs to different CPU channels. Assume VLANs
1 and 2 are mapped to the same CPU channel of 100 Mbit/s capacity. Then the
maximum theoretical routing throughput between the two VLAN interfaces is 50
Mbit/s full duplex, while the maximum theoretical routing throughput would be
100 Mbit/s full duplex if these VLANs were mapped to different CPU channels.
Note
Routing performance may also be limited by CPU performance, packet size
and enabled services.
A VLAN can only be mapped to a single CPU channel.
13.1.7 Dynamic VLANs
WeOS provides dynamic VLAN support via the WeOS Adaptive VLAN Trunking
(AVT) protocol. With AVT enabled, VLAN configuration on inter-switch links is
3 WeOS products with ”Corazon” platform (see section 1.5 ) have 1000 Mbit/s channels to CPU,
while others have 100 Mbit/s channels.
274 ➞ 2015 Westermo Teleindustri AB