C
HAPTER
1
| Introduction
Description of Software Features
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VIRTUAL LANS The switch supports up to 256 VLANs. A Virtual LAN is a collection of
network nodes that share the same collision domain regardless of their
physical location or connection point in the network. The switch supports
tagged VLANs based on the IEEE 802.1Q standard. Members of VLAN
groups can be manually assigned to a specific set of VLANs. This allows the
switch to restrict traffic to the VLAN groups to which a user has been
assigned. By segmenting your network into VLANs, you can:
◆ Eliminate broadcast storms which severely degrade performance in a
flat network.
◆ Simplify network management for node changes/moves by remotely
configuring VLAN membership for any port, rather than having to
manually change the network connection.
◆ Provide data security by restricting all traffic to the originating VLAN.
◆ Use private VLANs to restrict traffic to pass only between data ports
and the uplink ports, thereby isolating adjacent ports within the same
VLAN, and allowing you to limit the total number of VLANs that need to
be configured.
TRAFFIC
PRIORITIZATION
This switch prioritizes each packet based on the required level of service,
using four priority queues with strict or Weighted Round Robin Queuing. It
uses IEEE 802.1p and 802.1Q tags to prioritize incoming traffic based on
input from the end-station application. These functions can
be used to
provide independent priorities for delay-sensitive data and best-effort data.
This switch also supports several common methods of prioritizing layer 3/4
traffic to meet application requirements. Traffic can be prioritized based on
the priority bits in the IP frame’s Type of Service (ToS) octet or the number
of the TCP/UDP port. When these services are enabled, the priorities are
mapped to a Class of Service value by the switch, and the traffic then sent
to the corresponding output queue.
QUALITY OF SERVICE Differentiated Services (DiffServ) provides policy-based management
mechanisms used for prioritizing network resources to meet the
requirements of specific traffic types on a per-hop basis. Each packet is
classified upon entry into the network based on access lists, DSCP values,
or VLAN lists. Using access lists allows you select traffic based on Layer 2,
Layer 3, or Layer 4 information contained in each packet. Based on
network policies, different kinds of traffic can be marked for different kinds
of forwarding.
MULTICAST FILTERING Specific multicast traffic can be assigned to its own VLAN to ensure that it
does not interfere with normal network traffic and to guarantee real-time
delivery by setting the required priority level for the designated VLAN. The
switch uses IGMP Snooping and Query to manage multicast group
registration for IPv4 traffic, and MLD Snooping for IPv6 traffic. It also
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