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The enhancements for the TN3270 server include the following:
Cisco provides full RFC 1646 printer support in the TN3270 server. There are no configuration tasks or other options required in the CIP to take advantage of this support. Prior versions of the TN3270 server feature provided RFC 1647 support.
The Function Management Header (FMH) support is provided in the context of providing printer support for the Kanji character set. There are no configuration tasks or other options required in the CIP to take advantage of this support.
When a client does not support FMH and the host sends an FMH, the client will report a bad datastream or print random data. Prior to TN3270 server support of FMH, when a host sent an FMH the session would be unbound.
With suitable host and client software, you can now print double-byte character set characters over an LU type 1 session.
The TN3270 server now translates the host SNA character string (SCS) to 3270DS. In the initial release of TN3270 server, you were required to set up the host to provide either SCS or 3270 data stream (DS) data, depending on the needs of the client. That requirement no longer exists.
The system services control point (SSCP)-to-LU session from the host typically uses SCS even when the terminal is a 3270 device and expects to receive 3270DS data. However, only the LU-LU session uses 3270DS. With the USSTAB conversion feature, the SCS-to-3270DS data is converted automatically, even for clients that always require 3270DS data. There are no configuration tasks or other options required in the CIP to take advantage of this support.
The TN3270 server supports IP type of service (TOS) precedence setting. TOS is used in router networks to make routing decisions for the generated IP packets. The TN3270 server generates packets that comply to IP TOS and IP precedence values. (Refer to RFC 1349 for a description of IP TOS and IP precedence.)
The Cisco implementation of IP precedence allows values of 0 to 7 while TOS allows values from 0 to 15. You must choose appropriate values for TN3270 screens and printers consistent with your organization's policy.
At the protocol level, IP precedence allows a router network to discriminate between different types of traffic by giving different priorities to them. IP TOS allows router networks to discriminate between different types of traffic by giving different routing characteristics to them. Precedence and TOS values complement one another and provide flexibility in managing your network traffic.
In TN3270 server, two types of TN3270 clients connect: interactive screens or printers. Screens are interactive while printers need bulk data transfer. IP TOS and IP precedence allows you to discriminate between those two types of sessions and assign different precedence values to the interactive connection and the bulk data connection.
IP TOS and IP precedence values can be specified either at the TN3270 server command level or on the individual PU command level. Values can be specified on both levels, in which case siftdown will be used to determine value on individual PU. Siftdown is used when you configure values in TN3270 server configuration mode that apply to all entities in the server, yet you still can configure individual PUs at the PU configuration mode to alternative values. PU values not specifically changed use the values configured at the TN3270 server configuration mode. This flexibility provides a powerful, yet efficient, way to manage the values.
This feature is supported on the following platforms:
This section describes the following configuration tasks that are associated with the IP TOS and IP precedence feature:
To configure IP precedence, perform the following task in TN3270 server or TN3270 PU configuration mode:
| Task | Command |
|---|---|
| Configure the IP level. | ip precedence {screen | printer} value |
Use the no ip precedence screen or the no ip precedence printer commands to return the precedence value to a default of 0.
To configure IP TOS, perform the following task in TN3270 server or TN3270 PU configuration mode:
| Task | Command |
|---|---|
| Configure the IP TOS delay level. | ip tos {screen | printer} value |
Use the no ip tos screen or the no ip tos printer commands to return the precedence value to a default of 0.
This section provides sample configurations for configuring the IP TOS and IP precedence feature. Refer to the following configuration examples:
The following example changes IP precedence and IP TOS to different values under the TN3270 server for both the screen and printer. Note that any PUs defined under this configuration will inherit these values unless the corresponding parameter is specifically changed for that PU.
interface channel 3/2 tn3270-server ip precedence screen 6 ip precedence printer 3 ip tos screen 8 ip tos printer 4
In the following example, the PU PUS1 uses the IP TOS and IP precedence screen and printer values from the values provided in TN3270 server configuration mode. PUS2 uses the IP TOS screen and printer values defined in TN3270 server configuration mode. However, different values for IP precedence are provided for PUS2 under PU configuration mode.
interface channel 3/2 tn3270-server ip precedence screen 6 ip precedence printer 3 ip tos screen 8 ip tos printer 4 pu PUS1 05D18009 172.28.1.101 token-adapter 0 AC rsap 08 pu PUS2 05D18071 172.28.1.99 token-adapter 0 A4 rmac 4000.7470.00e7 ip precedence screen 7 ip precedence printer 0
This section documents new commands. All other commands used with this feature are documented in the Cisco IOS Release 11.2 command references. The following commands have been added as a result of feature enhancements:
Use the ip precedence TN3270 server command to specify the precedence level for IP traffic in the TN3270 server. The no form of this command removes the precedence value.
ip precedence {screen | printer} value| screen | Specifies the precedence is for the screen device. |
| printer | Specifies the precedence is for the printer device. |
| value | Sets the precedence priority. A value between 0 and 7, with 7 being the highest priority. The default is 0. |
The default is a precedence value of 0 for both screen and printer.
TN3270 server configuration mode
TN3270 PU configuration mode
This command first appeared in Cisco IOS Release 11.2 F.
Precedence values applied in TN3270 PU configuration mode override values applied in TN3270 server configuration mode.
You can enter new or different values for IP precedence without first using the no form of this command.
During initial Telnet negotiations to establish, or bind, the session an IP precedence value of 0 and IP TOS value of 0 is used. These values are used until the bind takes place. When the session is a type 2 bind, the TN3270 client is assumed to be screen; otherwise the client is assumed to be printer.
The following example assigns a precedence value of 3 to the printer:
ip precedence printer 3
You can use the index or search online to find documentation of related commands.
Use the ip tos TN3270 server command to specify the TOS level for IP traffic in the TN3270 server. The no form of this command removes the TOS value.
ip tos {screen | printer} value| screen | Specifies the TOS is for the screen device. |
| printer | Specifies the TOS is for the printer device. |
| value | Sets the TOS priority. A value between 0 and 15. The default is 0. |
The default is a TOS value of 0 for both screen and printer.
TN3270 server configuration mode
TN3270 PU configuration mode
This command first appeared in Cisco IOS Release 11.2 F.
TOS values applied in TN3270 PU configuration mode override values applied in TN3270 server configuration mode.
The default TOS values for screen and printer are 0. However, RFC 1349 recommends different default values. Specifically, the RFC recommends a default minimize screen delay value of 8 and a default maximize printer throughput value of 4. You must configure these values using the ip tos command if you want to comply to the defaults as stated in the RFC. Table 4 shows the values described in RFC 1349.
| Value | Definition | Action |
|---|---|---|
| 0 | All normal. | Use default metric. |
| 8 | Minimize delay. | Use delay metric. |
| 4 | Maximize throughput. | Use default metric. |
| 2 | Maximize reliability. | Use reliability metric. |
| 1 | Minimize monetary cost. | Use cost metric. |
| Other | Not defined. | Reserved for future use. |
During initial Telnet negotiations to establish, or bind, the session, an IP precedence value of 0 and IP TOS value of 0 is used. These values are used until the bind takes place. When the session is a type 2 bind, the TN3270 client is assumed to be screen; otherwise the client is assumed to be printer.
When you use the no form of the command, the TOS value is either set to 0 for that configuration mode or the value set at a previous (higher) configuration mode is used. For example, if you are at the TN3270 PU configuration mode and issue a no ip tos screen command, any value you configured previously at the TN3270 server configuration mode will take effect.
You can enter new or different values for TOS without first using the no form of this command.
In the following example, the TN3270 server TOS screen value is set to 10 and a specific PU TOS screen value is set to 0:
interface channel 3/2 tn3270-server ip tos screen 8 ip tos printer 4 pu PUS2 ip tos screen 0
You can use the index or search online to find documentation of related commands.
Support for the following Cisco proprietary MIBs has been enhanced:
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