zl50416 Zarlink Semiconductor, zl50416 Datasheet - Page 23

• Manufacturer Part Number: zl50416
• Description: Managed 16-port 10/100 M + 2-port 1 G Ethernet Switch
• Manufacturer: Zarlink Semiconductor

Each entry has 64 bits. Each port has a VLAN status field with the following two bits values:
-
-
-
-
Note: The VLAN aging time is controlled by register 402h.
5.4
The ZL50416's implementation of intelligent traffic switching provides filters for source and destination MAC
addresses. This feature filters unnecessary traffic, thereby providing intelligent control over traffic flows and
broadcast traffic.
MAC address filtering allows the ZL50416 to block an incoming packet to an interface when it sees a specified MAC
address in either the source address or destination address of the incoming packet. For example, if your network is
congested because of high utilization from a MAC address, you can filter all traffic transmitted from that address
and restore network flow, while you troubleshoot the problem.
5.5
Quality of Service (QoS) refers to the ability of a network to provide better service to selected network traffic over
various technologies. Primary goals of QoS include dedicated bandwidth, controlled jitter and latency (required by
some real-time and interactive traffic), and improved loss characteristics.
Traditional Ethernet networks have had no prioritization of traffic. Without a protocol to prioritize or differentiate
traffic, a service level known as “best effort” attempts to get all the packets to their intended destinations with
minimum delay; however, there are no guarantees. In a congested network or when a low-performance
switch/router is overloaded, “best effort” becomes unsuitable for delay-sensitive traffic and mission-critical data
transmission.
The advent of QoS for packet-based systems accommodates the integration of delay-sensitive video and
multimedia traffic onto any existing Ethernet network. It also alleviates the congestion issues that have previously
plagued such “best effort” networking systems. QoS provides Ethernet networks with the breakthrough technology
to prioritize traffic and ensure that a certain transmission will have a guaranteed minimum amount of bandwidth.
Extensive core QoS mechanisms are built into the ZL50416 architecture to ensure policy enforcement and
buffering of the ingress port, as well as weighted fair-queue(WFQ) scheduling at the egress port.
In the ZL50416, QoS-based policies sort traffic into a small number of classes and mark the packets accordingly.
The QoS identifier provides specific treatment to traffic in different classes, so that different quality of service is
provided to each class. Frame and packet scheduling and discarding policies are determined by the class to which
the frames and packets belong. For example, the overall service given to frames and packets in the premium class
will be better than that given to the standard class; the premium class is expected to experience lower loss rate or
delay.
The ZL50416 supports the following QoS techniques:
•
•
•
00: Port not a member of VLAN
01: Port is a member of VLAN, and is subject to aging (Do not use. Used by the aging module)
10: Port is a member of VLAN, and is subject to aging
11: Portmember of VLAN, and is not subject to aging
In a port-based setup, any station connected to the same physical port of the switch will have the same
transmit priority.
In a tag-based setup, a 3-bit field in the VLAN tag provides the priority of the packet. This priority can be
mapped to different queues in the switch to provide QoS.
In a TOS/DS-based set up, TOS stands for “Type of Service” that may include “minimize delay,” “maximize
throughput,” or “maximize reliability.” Network nodes may select routing paths or forwarding behaviors that
are suitably engineered to satisfy the service request.
MAC Address Filtering
Quality of Service
Zarlink Semiconductor Inc.
ZL50416
23
Data Sheet