This chapter describes the Class of Service (CoS) for IP feature.
CoS for IP is supported for the adapters and operating systems listed
in the following table.
|
| Windows NT 3.51, 4.0 | Windows 95, 98, 2000 | Windows 3.x (using IBM LAN Client) | OS/2 Warp 3.0 and later | Novell NetWare Server (4.11 and higher) |
|---|---|---|---|---|---|
| IBM 16/4 Token-Ring CardBus Adapter | Supported (Windows NT 4.0 only) | Supported | Not supported | Supported | Not supported |
| IBM 16/4 Token-Ring PCI Management Adapter | Supported | Supported | Not supported | Supported | Supported |
| IBM High-Speed 100/16/4 Token-Ring PCI Adapter | Supported | Supported | Supported | Supported | Supported |
| IBM 16/4 Token-Ring PCI Adapter 2 | |||||
| IBM 16/4 Token-Ring PCI Adapter 2 with Wake on LAN | |||||
| PCI Token-Ring Adapter | |||||
| PCI Wake on LAN Token-Ring Adapter | |||||
| Turbo 16/4 Token-Ring PC Card | Supported | Supported | Not supported | Not supported | Supported |
| Turbo 16/4 Token-Ring PC Card 2 |
Special note regarding token-ring PCI adapters
The IBM token-ring PCI adapters are enabled with advanced technology that lets higher-priority traffic expedite through the adapter, thus preventing this traffic from being held up behind lower-priority traffic.
The adapter includes multiple transmit paths for use by the device drivers. This multiple transmit path capability lets the driver pass a high-priority frame to the adapter and have this frame transmitted before a previously queued normal priority frame. This eliminates any traffic delays for the high-priority traffic from the moment the traffic is deemed to be high-priority in the device driver.
This advanced function exists in all IBM token-ring PCI adapters.
The ability to assign relative priorities, or degrees of importance, to traffic as it traverses a network has existed in token-ring networks since the inception of the token-ring standard. Unfortunately, there has never been a method to assign the priorities to the traffic as the frames were transmitted. CoS for IP solves this problem by allowing network managers to assign priorities to IP traffic transmitted by an IP host.
With the use of CoS for IP, you can categorize your IP traffic on the network and assign a degree of importance in the network to certain types of IP traffic. This prevents traffic considered to be of low importance from taking valuable network bandwidth away from important traffic. The backing up of a server farm or a session of a computer game will no longer adversely impact the streaming of an educational video session or a real-time video conference.
CoS for IP makes use of a traffic prioritization mechanism that has always existed in the token-ring architecture but has never been exploited by higher-layer protocols and applications. CoS for IP does not rely on any special enablement to the infrastructure of the network. That is, the switches and bridges of the network do not necessarily need to know that CoS for IP is being used. Even though the network is not aware of this traffic prioritization mechanism, CoS for IP allows the traffic that has been assigned a high priority to maintain this high-priority status from the time that the traffic enters the network to its final destination.
In addition, CoS for IP does not require new protocol stacks and applications that are aware of traffic prioritization. In fact, the traffic being treated as high priority is up to the network manager and does not even have to be multimedia related. If performing a backup of a server is considered a high priority then this traffic can be deemed more important by the network manager than other traffic on the network.
Because CoS for IP uses a token-ring mechanism for implementing traffic prioritization, the best results occur when the traffic that has been given a priority status is sent through a Layer 2 switched, or bridged, path and travels entirely on token-ring networks. IBM's Route Switching function solves this requirement by establishing the Layer 2 path even when the two end stations reside on different subnets. With the advent of Web-based networking and intranet-based IP networks, intersubnet communications is becoming more the normal situation. Route Switching and CoS for IP work together to resolve growing network performance problems not just for high-priority traffic but for all traffic in the network.
CoS for IP can be used to ensure that time-sensitive traffic, such as streaming audio or video, arrives at the destination computer within the required time. To make use of CoS for IP, a network manager would determine the protocol and the port range being used by the server application and configure CoS for IP with these values on the server. For example, a network manager might have a server running a RealNetworks streaming audio server application that is sending audio traffic to clients using UDP port ranges, 26992 through 29040. The network manager would configure CoS for IP for these values and assign a priority level for this range.
CoS for IP can be managed using LAN Adapter Management Agent. The following values can be displayed:.
LAN Adapter Transmit Priority Information Displays the general transmit priority capabilities of the adapter. For example, this attribute displays the number of physical transmit channels supported by the adapter hardware.
LAN Adapter Transmit Priority Distribution Shows the frame count and byte count for each priority level. Displaying these values will indicate the priority at which traffic is being sent.
LAN Adapter Class of Service Information Displays the number of port ranges defined for each protocol.
LAN Adapter Class of Service TCP Port Ranges Displays each of the defined port ranges for the TCP protocol. Displaying these values will confirm that the port ranges configured have been accepted and are being used by the CoS for IP support.
LAN Adapter Class of Service UDP Port Ranges Displays each of the defined port ranges for the UDP protocol. Displaying these values will confirm that the port ranges configured have been accepted and are being used by the CoS for IP support.
There are no special requirements for the machines that will make use of CoS for IP other than having a supported IBM adapter and the correct level of device driver.
CoS for IP makes use of the priority bits defined by the token-ring architecture. Because of the use of these Layer 2 bit fields, traffic being assigned a higher-than-normal priority should be traversing only a Layer 2 path in order to achieve the full effects of CoS for IP. Route Switching complements CoS for IP by attempting to establish a Layer 2 connection for all IP traffic that would otherwise traverse Layer 3 devices.
Installation and configuration information are particular to each adapter and are explained in the installation guide for your adapter. Go to http://www.ibm.com/networking and view the installation books for your adapter.
CoS for IP uses the destination port number of outbound TCP and UDP traffic to determine the Class of Service, or priority, of the traffic. Once the range of port numbers used for a particular TCP- or UDP-based application has been determined, this port range is simply passed to the CoS for IP function within the device driver through the following configuration parameters.
CoS for IP is enabled in the device drivers by simply defining one or more TCP or UDP port ranges. A port range is defined by a starting port value and an ending port value. Each of these values is inclusive, meaning the port values that make up a port range include the starting and ending values. For each port range defined, you must select a priority value from 1 to 6. You can define a maximum of 15 port ranges for each of the two protocols. When configuring CoS for IP in either the OS/2 or Novell Server environments, define these port range parameters in the following format:
ParmValue := <PortRange>[<PortRange><PortRange>] PortRange := <PortNumber><PortNumber><PriorityValue> PortNumber := a 4-character hexadecimal value. PriorityValue := a 1-character value from 1 to 6.
A bridging device in a token-ring network will forward traffic at a priority of 4 when necessary. If CoS for IP is being used in a network made up of bridges this fact must be taken into account. It might be necessary to make use of only priorities 5 and 6 when defining port ranges in order to keep the traffic at a higher priority than the bridged traffic. When the higher-priority traffic travels across a bridging function the bridge should maintain the frame priority. For example, a network manager has defined certain UDP traffic to be priority 6 and this traffic is to flow across a number of bridges as it travels from a server to a client. When this traffic is forwarded onto subsequent rings by the bridges, the bridges will now forward it with a priority of 6 instead of 4.
Each of the following installation and configuration sections assumes that the adapter is already installed and configured. The following sections define only the steps required to enable CoS for IP. If the adapter is not installed, refer to the installation manual for the adapter you are using.
If you are using a token-ring PCI adapter on Windows 95 OSR2, Windows 98, Windows NT, or Windows 2000, use the instructions in Token-ring PCI adapters (on Windows 95 OSR2, Windows 98, Windows NT, and Windows 2000) to set CoS for IP parameters.
If you are using the IBM Turbo 16/4 Token-Ring PC Card 2, use the instructions in IBM Turbo 16/4 Token-Ring PC Card 2 to set CoS for IP parameters.
Otherwise, use the instructions in this section.
To set the CoS for IP parameters, perform the following steps:
| Note: | Class of Service for IP supports a maximum of 15 defined port ranges for each protocol. |
To set the CoS for IP parameters, perform the following steps:
| Note: | Class of Service for IP supports a maximum of 15 defined port ranges for each protocol. |
To set the CoS for IP parameters, perform the following steps:
| Note: | Class of Service for IP supports a maximum of 15 defined port ranges for each protocol. |
To set the CoS for IP parameters, perform the following steps:
For Class of Service configuration:
To set the CoS for IP parameters, perform the following steps:
| Note: | To install LCINST.EXE to a hard disk from the LAN Client diskettes, insert LAN Client diskette 1 in drive A and enter install. |
To set the CoS for IP parameters, perform the following steps: