Owner manual
Table Of Contents
- Contents
- Figures
- Tables
- Preface
- Section I
- Basic Operations
- Chapter 1
- Overview
- Chapter 2
- Enhanced Stacking
- Chapter 3
- SNMPv1 and SNMPv2c
- Chapter 4
- MAC Address Table
- Chapter 5
- Static Port Trunks
- Chapter 6
- LACP Port Trunks
- Chapter 7
- Port Mirror
- Section II
- Advanced Operations
- Chapter 8
- File System
- Chapter 9
- Event Logs and the Syslog Client
- Chapter 10
- Classifiers
- Chapter 11
- Access Control Lists
- Chapter 12
- Class of Service
- Chapter 13
- Quality of Service
- Chapter 14
- Denial of Service Defenses
- Chapter 15
- Power Over Ethernet
- Section III
- Snooping Protocols
- Chapter 16
- IGMP Snooping
- Chapter 17
- MLD Snooping
- Chapter 18
- RRP Snooping
- Chapter 19
- Ethernet Protection Switching Ring Snooping
- Section IV
- SNMPv3
- Chapter 20
- SNMPv3
- Section V
- Spanning Tree Protocols
- Chapter 21
- Spanning Tree and Rapid Spanning Tree Protocols
- Chapter 22
- Multiple Spanning Tree Protocol
- Section VI
- Virtual LANs
- Chapter 23
- Port-based and Tagged VLANs
- Chapter 24
- GARP VLAN Registration Protocol
- Chapter 25
- Multiple VLAN Modes
- Chapter 26
- Protected Ports VLANs
- Chapter 27
- MAC Address-based VLANs
- Section VII
- Routing
- Chapter 28
- Internet Protocol Version 4 Packet Routing
- Supported Platforms
- Overview
- Routing Interfaces
- Interface Names
- Static Routes
- Routing Information Protocol (RIP)
- Default Routes
- Equal-cost Multi-path (ECMP) Routing
- Routing Table
- Address Resolution Protocol (ARP) Table
- Internet Control Message Protocol (ICMP)
- Routing Interfaces and Management Features
- Local Interface
- AT-9408LC/SP AT-9424T/GB, and AT-9424T/SP Switches
- Routing Command Example
- Non-routing Command Example
- Upgrading from AT-S63 Version 1.3.0 or Earlier
- Chapter 29
- BOOTP Relay Agent
- Chapter 30
- Virtual Router Redundancy Protocol
- Section VIII
- Port Security
- Chapter 31
- MAC Address-based Port Security
- Chapter 32
- 802.1x Port-based Network Access Control
- Section IX
- Management Security
- Chapter 33
- Web Server
- Chapter 34
- Encryption Keys
- Chapter 35
- PKI Certificates and SSL
- Chapter 36
- Secure Shell (SSH)
- Chapter 37
- TACACS+ and RADIUS Protocols
- Chapter 38
- Management Access Control List
- Appendix A
- AT-S63 Management Software Default Settings
- Address Resolution Protocol Cache
- Boot Configuration File
- BOOTP Relay Agent
- Class of Service
- Denial of Service Defenses
- 802.1x Port-Based Network Access Control
- Enhanced Stacking
- Ethernet Protection Switching Ring (EPSR) Snooping
- Event Logs
- GVRP
- IGMP Snooping
- Internet Protocol Version 4 Packet Routing
- MAC Address-based Port Security
- MAC Address Table
- Management Access Control List
- Manager and Operator Account
- Multicast Listener Discovery Snooping
- Public Key Infrastructure
- Port Settings
- RJ-45 Serial Terminal Port
- Router Redundancy Protocol Snooping
- Server-based Authentication (RADIUS and TACACS+)
- Simple Network Management Protocol
- Simple Network Time Protocol
- Spanning Tree Protocols (STP, RSTP, and MSTP)
- Secure Shell Server
- Secure Sockets Layer
- System Name, Administrator, and Comments Settings
- Telnet Server
- Virtual Router Redundancy Protocol
- VLANs
- Web Server
- Appendix B
- SNMPv3 Configuration Examples
- Appendix C
- Features and Standards
- 10/100/1000Base-T Twisted Pair Ports
- Denial of Service Defenses
- Ethernet Protection Switching Ring Snooping
- Fiber Optic Ports (AT-9408LC/SP Switch)
- File System
- DHCP and BOOTP Clients
- Internet Protocol Multicasting
- Internet Protocol Version 4 Routing
- MAC Address Table
- Management Access and Security
- Management Access Methods
- Management Interfaces
- Management MIBs
- Port Security
- Port Trunking and Mirroring
- Spanning Tree Protocols
- System Monitoring
- Traffic Control
- Virtual LANs
- Virtual Router Redundancy Protocol
- Appendix D
- MIB Objects
- Index

Chapter 13: Quality of Service
146 Section II: Advanced Operations
Policies
QoS policies consist of a collection of user defined traffic classes. A policy
can be assigned to more than one port, but a port may only have one
policy.
Note that the switch can only perform error checking of parameters and
parameter values for the policy and its traffic classes and flow groups
when the policy is set on a port.
QoS controls are applied to ingress traffic on ports. Therefore, to control a
particular type of traffic, an appropriate QoS policy must be attached to
each port that type of traffic ingresses.
Although a policy can be applied to an egress port, the classifiers and the
QoS controls are actually applied by the switch on the ingress ports of the
traffic. This means the parameters used to classify the traffic and the
actions specified by the policy are checked and applied on the ingress
traffic of every port, before the traffic reaches an egress queue. As a
consequence, a policy is never applied to the whole aggregated traffic of a
designated egress port, but rather to the individual ingress flows destined
to the port.
The effects of this behavior become evident when using the maximum
bandwidth feature of QoS. Here is an example. Suppose you have a policy
that assigns 5 Mbps of maximum bandwidth to an egress port. Now
assume there are 10 ports on the switch where ingress traffic matches the
criteria specified in the classifier assigned to the policy of the egress port.
Since the policy considers each ingress flow separately, the result would
be a maximum bandwidth of 50 Mbps (10 x 5 Mbps) on the egress port,
because there are 10 flows, one from each ingress port, directed to the
egress port.
An additional factor to consider when specifying an egress port in a policy
is that if the destination MAC address of the traffic flow has not been
learned by the egress port or, alternatively, added as a static address to
the port, the policy remains inactive. This is because the ingress ports
consider the traffic as unknown traffic and flood the traffic to all the ports.
This applies equally to unknown unicast and unknown multicast traffic, as
well as broadcast traffic.