41
Select
Enable
in the
IGMP Snooping
area to enable the function.
Step 2
Select Disable or Enable in the Discarding Unknown IGMP Packets area.
Step 3
Click
Add
.
Step 4
Add VLAN
Figure 3-51
Set VLAN ID and querier address, and select the
Querier Election
box to enable the querier
Step 5
Click
OK
.
Step 6
3.2.6
QoS
QoS (Quality of Service) is used to evaluate the capability that server meets customer’s service
demands. In Internet, what QoS evaluates is the service capability of network forwarding and packet.
QoS can evaluate from the different aspects according to the various services provided by the
network. QoS evaluates bandwidth, delay, dithering, and packet loss during packet and forwarding.
Congestion
Congestion is common in a complex Internet packet switched environment. See the following
example:
Flow congestion
Figure 3-52
1)
The packet comes in the device by the high-speed link and exits by low-speed link.
2)
The packet comes in the device from multiple ports and exits from one port (The speed rate of
multiple ports larger than that of the exit port).
If the flow arrives at linear speed, it will encounter the resource chock point, and then the congestion
will generate.
Besides the aggression bandwidth, any other resource shortages (such as the shortages of
distributive processing time, buffer and memory resources) will cause congestion. Additionally, the
