Chapter 1
| Introduction
Description of Software Features
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members from being segmented from the rest of the group (as sometimes
occurs with IEEE 802.1D STP).
Virtual LANs
The switch supports up to 4094 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 dynamically learned via
GVRP, or ports 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, except
where a connection is explicitly defined via the switch's routing service.
◆
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.
◆
Use protocol VLANs to restrict traffic to specified interfaces based on protocol
type.
Traffic Prioritization
This switch prioritizes each packet based on the required level of service, using
eight priority queues with strict priority, Weighted Round Robin (WRR) scheduling,
or a combination of strict and weighted 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 using DSCP, or IP Precedence. 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, IP Precedence or DSCP values, or VLAN lists. Using access lists
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