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Cisco IOS Release 12.0 Bridging and IBM Networking Command Reference
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About the Cisco IOS Software Documentation
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Using Cisco IOS Software
- Part 1: Bridging
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Part 2: IBM Networking
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Remote Source-Route Bridging Commands
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DLSw+ Commands
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Serial Tunnel and Block Serial Tunnel Commands
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LLC2 and SDLC Commands
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IBM Network Media Translation Commands
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DSPU and SNA Service Point Commands
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SNA Frame Relay Access Commands
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APPN Configuration Commands
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Cisco Database Connection Commands
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NCIA Server Configuration Commands
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Cisco Mainframe Channel Connection Commands
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Airline Product Set Commands
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- Part 3: Appendix
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Table Of Contents
LLC2 and SDLC Commands
Logical Link Control, type 2 (LLC2) protocol provides connection-oriented service and is widely used in LAN environments, particularly among IBM communication systems connected by Token Ring. The Cisco IOS software supports LLC2 connections over Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI).
The LLC2 commands provide operations that support the following features:
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Local acknowledgment in remote source-route bridging (RSRB)
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SDLC is used as the primary Systems Network Architecture (SNA) link-layer protocol for WAN links. SDLC defines two types of network nodes: primary and secondary. Primary nodes poll secondary nodes in a predetermined order. Secondaries then transmit if they have outgoing data. When configured as primary and secondary nodes, routers are established as SDLC stations.
The SDLC commands described in this chapter pertain to routers configured as SDLC stations. This is in contrast to a device configured for SDLC Transport where the router is not configured as an SDLC station, but acts as an intermediary, passing SDLC frames between two SDLC stations across a mixed-media, multiprotocol environment.
The SDLC commands support the following features:
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Use the commands in this chapter to adjust the LLC2 and SDLC parameters. For LLC2 and SDLC parameter configuration information and examples, refer to the "Configuring LLC2 and SDLC Parameters" chapter in the Bridging and IBM Networking Configuration Guide.
encapsulation sdlc
Use the encapsulation sdlc interface configuration command to configure an SDLC interface.
encapsulation sdlc
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
The encapsulation sdlc command must be used to configure an SDLC interface if you plan to implement DLSw+ or Frame Relay access support.
SDLC defines two types of network nodes: primary and secondary. Primary nodes poll secondary nodes in a predetermined order. Secondaries then transmit if they have outgoing data. When configured as primary and secondary nodes, our routers are established as SDLC stations. Use the sdlc role interface configuration command to establish the role as primary or secondary.
In the IBM environment, a front-end processor (FEP) is the primary station and establishment controllers (ECs) are secondary stations. In a typical scenario, an EC may be connected to dumb terminals and to a Token Ring network at a local site. At the remote site, an IBM host connects to an IBM FEP, which can also have links to another Token Ring LAN. Typically, the two sites are connected through an SDLC leased line.
If a router is connected to an EC, it takes over the function of the FEP, and must therefore be configured as a primary SDLC station. If the router is connected to a FEP, it takes the place of the EC, and must therefore be configured as a secondary SDLC station.
Examples
The following example configures an SDLC interface:
interface serial 2/6no ip addressencapsulation sdlcRelated Commands
encapsulation sdlc-primary
Use the encapsulation sdlc-primary interface configuration command to configure the router as the primary SDLC station if you plan to configure the SDLLC media translation feature.
encapsulation sdlc-primary
no encapsulation sdlc-primary
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
The encapsulation sdlc-primary or encapsulation sdlc-secondary command must be used to configure an SDLC interface. To use the encapsulation sdlc-primary command, first select the interface on which you want to enable SDLC. Then establish the router as a primary station. Next, assign secondary station addresses to the primary station using the sdlc address command.
SDLC defines two types of network nodes: primary and secondary. Primary nodes poll secondary nodes in a predetermined order. Secondaries then transmit if they have outgoing data. When configured as primary and secondary nodes, our routers are established as SDLC stations.
In the IBM environment, a front-end processor (FEP) is the primary station and establishment controllers (ECs) are secondary stations. In a typical scenario, an EC may be connected to dumb terminals and to a Token Ring network at a local site. At the remote site, an IBM host connects to an IBM FEP, which can also have links to another Token Ring LAN. Typically, the two sites are connected through an SDLC leased line.
If a router is connected to an EC, it takes over the function of the FEP, and must therefore be configured as a primary SDLC station. If the router is connected to an FEP, it takes the place of the EC, and must therefore be configured as a secondary SDLC station.
Examples
The following example shows configures serial interface 0 on your router to allow two SDLC secondary stations to attach through a modem-sharing device (MSD) with addresses C1 and C2:
! enter a global command if you have not alreadyinterface serial 0encapsulation sdlc-primarysdlc address c1sdlc address c2Related Commands
encapsulation sdlc-secondary
Use the encapsulation sdlc-secondary interface configuration command to configure the router as a secondary SDLC station if you plan to configure the SDLLC media translation feature.
encapsulation sdlc-secondary
no encapsulation sdlc-secondary
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
An encapsulation sdlc-primary or encapsulation sdlc-secondary command must be used to configure an SDLC interface. To use the encapsulation sdlc-secondary command, first select the interface on which you want to enable SDLC. Then establish the router as a secondary station. Next, assign secondary station addresses to the primary station using the sdlc address command.
SDLC defines two types of network nodes: primary and secondary. Primary nodes poll secondary nodes in a predetermined order. Secondaries then transmit if they have outgoing data. When configured as primary and secondary nodes, our devices are established as SDLC stations.
In the IBM environment, a front-end processor (FEP) is the primary station and establishment controllers (ECs) are secondary stations. In a typical scenario, an EC may be connected to dumb terminals and to a Token Ring network at a local site. At the remote site, an IBM host connects to an IBM FEP, which can also have links to another Token Ring LAN. Typically, the two sites are connected through an SDLC leased line.
If a router is connected to an EC, it takes over the function of the FEP, and must therefore be configured as a primary SDLC station. If the router is connected to a FEP, it takes the place of the EC, and must therefore be configured as a secondary SDLC station.
Examples
The following example establishes the router as a secondary SDLC station:
interface serial 0encapsulation sdlc-secondaryRelated Commands
llc2 ack-delay-time
Use the llc2 ack-delay-time internal adapter configuration command to set the amount of time the Cisco IOS software waits for an acknowledgment before sending the next set of information frames.
llc2 ack-delay-time milliseconds
Syntax Description
Defaults
100 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
Upon receiving an information frame, each LLC2 station starts a timer. If the timer expires, an acknowledgment will be sent for the frame, even if the llc2 ack-max number of received frames has not been reached. Experiment with the value of the llc2 ack-delay-time command to determine the configuration that balances acknowledgment network overhead and quick response time (by receipt of timely acknowledgments).
Use this command in conjunction with the llc2 ack-max command to determine the maximum number of information frames the Cisco IOS software can receive before sending an acknowledgment.
Examples
In the following example, the software allows a 100-millisecond delay before I-frames must be acknowledged:
! enter a global command, if you have not alreadyinterface tokenring 0! sample ack-max commandllc2 ack-max 3! allow a 100 millisecond delay before I-frames must be acknowledgedllc2 ack-delay-time 100At time 0, two information frames are received. The llc2 ack-max amount of three has not been reached, so no acknowledgment for these frames is sent. If a third frame, which would force the software to send an acknowledgment, is not received in 100 milliseconds, an acknowledgment will be sent anyway, because the llc2 ack-delay timer expires. At this point, because all frames are acknowledged, the counter for the ack-max purposes will be reset to zero.
Related Commands
Controls the maximum amount of information frames the Cisco IOS software can receive before it must send an acknowledgment.
Displays the LLC2 connections active in the router.
llc2 ack-max
Use the llc2 ack-max internal adapter configuration command to control the maximum amount of information frames the Cisco IOS software can receive before it must send an acknowledgment.
llc2 ack-max packet-count
Syntax Description
packet-count
Maximum number of packets the software will receive before sending an acknowledgment. The minimum is 1 packet and the maximum is 255 packets. The default is 3 packets.
Defaults
3 packets
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
An LLC2-speaking station can send only a predetermined number of frames before it must wait for an acknowledgment from the receiver. If the receiver waits until receiving a large number of frames before acknowledging any of them, and then acknowledges them all at once, it reduces overhead on the network.
For example, an acknowledgment for five frames can specify that all five have been received, as opposed to sending a separate acknowledgment for each frame. To keep network overhead low, make this parameter as large as possible.
However, some LLC2-speaking stations expect this to be a low number. Some NetBIOS-speaking stations expect an acknowledgment to every frame. Therefore, for these stations, this number is best set to 1. Experiment with this parameter to determine the best configuration.
Examples
In the following example, the software is configured to receive up to seven frames before it must send an acknowledgment. Seven frames is the maximum allowed by SNA before a reply must be received:
! enter a global command, if you have not alreadyinterface tokenring 0! receive up to seven frames before sending an acknowledgmentllc2 ack-max 7! sample delay-time commandllc2 ack-delay-time 100Related Commands
llc2 idle-time
Use the llc2 idle-time internal adapter configuration command to control the frequency of polls during periods of idle time (no traffic).
llc2 idle-time milliseconds
Syntax Description
Defaults
10000 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
Periodically, when no information frames are being transmitted during an LLC2 session, LLC2 stations are sent a Receiver Ready frame to indicate they are available. Set the value for this command low enough to ensure a timely discovery of available stations, but not too low, or you will create a network overhead with too many Receiver Ready frames.
Examples
In the following example, the Cisco IOS software waits 20000 milliseconds before sending a Receiver Ready ("are you there") frame:
! enter a global command, if you have not already interface tokenring 0! wait 20000 milliseconds before sending receiver-ready framesllc2 idle-time 20000Related Commands
llc2 local-window
Use the llc2 local-window internal adapter configuration command to control the maximum number of information frames the Cisco IOS software sends before it waits for an acknowledgment.
llc2 local-window packet-count
no llc2 local-window packet-count
Syntax Description
packet-count
Maximum number of packets that can be sent before the software must wait for an acknowledgment. The minimum is 1 packet and the maximum is 127 packets. The default is 7 packets.
Defaults
7 packets
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
An LLC2-speaking station can send only a predetermined number of frames before it must wait for an acknowledgment from the receiver. Set this number to the maximum value that can be supported by the stations with which the router communicates. Setting this value too large can cause frames to be lost, because the receiving station may not be able to receive all of them.
Examples
In the following example, the software will send as many as 30 information frames through Token Ring interface 1 before it must receive an acknowledgment:
! enter a global command, if you have not alreadyinterface tokenring 1llc2 local-window 30Related Commands
Controls the maximum amount of information frames the Cisco IOS software can receive before it must send an acknowledgment.
Displays the LLC2 connections active in the router.
llc2 n2
Use the llc2 n2 internal adapter configuration command to control the amount of times the Cisco IOS software retries sending unacknowledged frames or repolls remote busy stations.
llc2 n2 retry-count
no llc2 n2
Syntax Description
retry-count
Number of times the software retries operations. The minimum is 1 retry and the maximum is 255 retries. The default is 8 retries.
Defaults
8 retries
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
An LLC2 station must have some limit to the number of times it will resend a frame when the receiver of that frame has not acknowledged it. After the software is told that a remote station is busy, it will poll again based on the retry-count value. When this retry count is exceeded, the LLC2 station terminates its session with the other station. Set this parameter to a value that balances between frame checking and network performance.
Examples
In the following example, the software will resend a frame up to four times through Token Ring interface 1 before it must receive an acknowledgment. Because you generally do not need to change the retry limit, this example shows you how to reset the limit to the default of 8.
! enter a global command, if you have not alreadyinterface tokenring 1! retry value of 8llc2 n2 8Related Commands
llc2 nw
To increase the window size for consecutive good I-frames received, use the llc2 nw internal adapter configuration command. To revert to the default setting, use the no form of this command.
llc2 nw window-size-increase
no llc2 nw
Syntax Description
window-size-increase
Number of frames to increase the window size for consecutive good I-frames received (0 is disabled). The default is 0.
Defaults
0 (disabled)
Command Modes
Internal adapter configuration
Command History
Examples
In the following example, the window size for Token Ring interface 1 is increased by 1 frame when consecutive good I-frames are received:
! enter a global command, if you have not alreadyinterface tokenring 1! increase window size by 1llc2 nw 1Related Commands
llc2 recv-window
To control the number of frames in the receive window, use the llc2 recv-window internal adapter configuration command. To revert to the default setting, use the no form of this command.
llc2 recv-window frame-count
no llc2 recv-window
Syntax Description
Defaults
7 frames
Command Modes
Internal adapter configuration
Command History
Examples
In the following example, the receive window for Token Ring interface 1 contains 11 frames:
! enter a global command, if you have not alreadyinterface tokenring 1! 11 frames in the receive windowllc2 recv-window 11Related Commands
llc2 send-window
To control the number of frames in the send window, use the llc2 send-window internal adapter configuration command. To revert to the default setting, use the no form of this command.
llc2 send-window frame-count
no llc2 send-window
Syntax Description
Defaults
7 frames
Command Modes
Internal adapter configuration
Command History
Examples
In the following example, the send window for Token Ring interface 1 contains 11 frames:
! enter a global command, if you have not alreadyinterface tokenring 1! 11 frames in the send windowllc2 send-window 11Related Commands
llc2 t1-time
Use the llc2 t1-time internal adapter configuration command to control the amount of time the Cisco IOS software will wait before resending unacknowledged information frames.
llc2 t1-time milliseconds
Syntax Description
Defaults
1000 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
Use this command in conjunction with the llc2 n2 command to provide a balance of network monitoring and performance. Ensure that enough time is allowed to account for the round trip between the router and its LLC2-speaking stations under heavy network loading conditions.
Examples
In the following example, the software will wait 4000 milliseconds before resending an unacknowledged frame through Token Ring interface 2:
! enter a global command, if you have not alreadyinterface tokenring 2! wait 4000 milliseconds before retransmitting a frame through tokenring 2llc2 t1-time 4000Related Commands
llc2 tbusy-time
Use the llc2 tbusy-time internal adapter configuration command to control the amount of time the Cisco IOS software waits until repolling a busy remote station.
llc2 tbusy-time milliseconds
Syntax Description
milliseconds
Number of milliseconds the software waits before repolling a busy remote station. The minimum is 1 millisecond and the maximum is 60000 milliseconds. The default is 9600 milliseconds.
Defaults
9600 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
An LLC2 station has the ability to notify other stations that it is temporarily busy, so the other stations will not attempt to send any new information frames. The frames sent to indicate this are called Receiver Not Ready (RNR) frames. Change the value of this parameter only to increase the value for LLC2-speaking stations that have unusually long busy periods before they clear their busy status. Increasing the value will prevent the stations from timing out.
Examples
In the following example, the software will wait up to 12000 milliseconds before attempting to poll a remote station through Token Ring interface 0 to learn the station's status:
! enter a global command, if you have not alreadyinterface tokenring 0! wait 12000 milliseconds before polling a station through tokenring 0llc2 tbusy-time 12000Related Commands
llc2 tpf-time
Use the llc2 tpf-time internal adapter configuration command to set the amount of time the Cisco IOS software waits for a final response to a poll frame before resending the poll frame.
llc2 tpf-time milliseconds
no llc2 tpf-time milliseconds
Syntax Description
Defaults
1000 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
When sending a command that must receive a response, a poll bit is sent in the frame. This is the receiving station's clue that the sender is expecting some response from it, be it an acknowledgment of information frames or an acknowledgment of more administrative tasks, such as starting and stopping the session. Once a sender gives out the poll bit, it cannot send any other frame with the poll bit set until the receiver replies with a frame containing a final bit set. If the receiver is faulty, it may never return the final bit to the sender. Therefore, the sender could be waiting for a reply that will never come. To avoid this problem, when a poll-bit-set frame is sent, a transmit-poll-frame (TPF) timer is started. If this timer expires, the software assumes that it can send another frame with a poll bit.
Usually, you will not want to change this value. If you do, the value should be larger than the T1 time, set with the llc2 t1-time command. The T1 time determines how long the software waits for receipt of an acknowledgment before sending the next set of frames.
Examples
While you generally will not want to change the transmit-poll-frame time, this example sets the TPF time to 3000 milliseconds. Because the TPF time should be larger than the LLC2 T1 time, this example shows the TPF time as double the LLC2 T1 time.
! enter a global command, if you have not alreadyinterface tokenring 0! send a poll bit set through tokenring 0 after a 3000 ms delayllc2 tpf-time 3000! wait 1500 milliseconds for an acknowledgment before resending I-framesllc2 t1-time 1500Related Commands
llc2 trej-time
Use the llc2 trej-time internal adapter configuration command to control the amount of time the Cisco IOS software waits for a correct frame after sending a reject command to the remote LLC2 station.
llc2 trej-time milliseconds
Syntax Description
Defaults
3200 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
When an LLC2 station sends an information frame, a sequence number is included in the frame. The LLC2 station that receives these frames will expect to receive them in order. If it does not, it can reject a frame and indicate which frame it is expecting to receive instead. Upon sending a reject, the LLC2 station starts a reject timer. If the frames are not received before this timer expires, the session is disconnected.
Examples
In the following example, the software will wait up to 1000 milliseconds to receive a previously rejected frame before resending its reject message to the station that sent the frame:
! enter a global command, if you have not alreadyinterface tokenring 0! wait 1000 milliseconds before resending a reject message through tokenring 0llc2 trej-time 1000Related Commands
Controls the number of times the Cisco IOS software retries sending unacknowledged frames or repolls remote busy stations.
Displays the LLC2 connections active in the router.
llc2 xid-neg-val-time
Use the llc2 xid-neg-val-tim internal adapter configuration command to control the frequency of exchange of identification (XID) transmissions by the Cisco IOS software.
llc2 xid-neg-val-time milliseconds
no llc2 xid-neg-val-time milliseconds
Syntax Description
Defaults
0 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
Do not change the llc2 xid-neg-val-time parameter unless requested by your technical support representative.
LLC2-speaking stations can communicate exchange of identification (XID) frames to each other. These frames identify the stations at a higher level than the MAC address and also can contain information about the configuration of the station. These frames are typically sent only during setup and configuration periods when it is deemed that sending them is useful. The greatest frequency at which this information is transferred is controlled by this timer.
Examples
The following example shows how to reset the frequency of XID transmissions to the default of
0 milliseconds:! enter a global command, if you have not alreadyinterface tokenring 0! set the frequency of XID transmissions to 0llc2 xid-neg-val-time 0Related Commands
Sets the amount of time the Cisco IOS software waits for a reply to XID frames before dropping the session.
Displays the LLC2 connections active in the router.
llc2 xid-retry-time
Use the llc2 xid-retry-time internal adapter configuration command to set the amount of time the Cisco IOS software waits for a reply to exchange of identification (XID) frames before dropping the session.
llc2 xid-retry-time milliseconds
no llc2 xid-retry-time milliseconds
Syntax Description
Defaults
60000 milliseconds
Command Modes
Internal adapter configuration
Command History
Usage Guidelines
Set this value greater than the value of the T1 time, or the time the software waits for an acknowledgment before dropping the session. T1 time is set with the llc2 t1-time command.
Examples
The following example sets the software to wait up to 60000 milliseconds for a reply to XID frames it sent to remote stations (which resets the value to its default):
! enter a global command, if you have not alreadyinterface tokenring 0! wait 60000 milliseconds for a reply to XID framesllc2 xid-retry-time 60000Related Commands
sdlc address
Use the sdlc address interface configuration command to assign a set of secondary stations attached to the serial link. Use the no form of this command to remove an assigned secondary station.
sdlc address hexbyte [echo] [switched]
no sdlc address hexbyte [echo] [switched]
Syntax Description
Defaults
No secondary stations are assigned.
Command Modes
Interface configuration
Command History
Usage Guidelines
Before using this command, first select the interface on which you want to enable SDLC. Then establish the router as a primary station with the encapsulation sdlc-primary command. Next, assign secondary station addresses to the primary station using the sdlc address command. The addresses are given in hexadecimal (base 16) and are given one per line.
The optional keyword echo is valid only for TG interfaces. When you use the echo keyword, hexbyte is the nonecho SDLC address.
Examples
The following example shows how to configure serial interface 0 to have two SDLC secondary stations attached to it through a modem-sharing device with addresses C1 and C2:
interface serial 0encapsulation sdlc-primarysdlc address c1sdlc address c2Related Commands
sdlc address ff ack-mode
Use the sdlc address ff ack-mode interface configuration command to configure the IBM reserved address ff as a valid local address.
sdlc address ff ack-mode
Syntax Description
This command has no arguments or keywords.
Command Modes
Interface configuration
Command History
Usage Guidelines
The sdlc address ff ack-mode command is used to support applications that require local termination of an SDLC connection with address FF. This command should be used only if you use the SDLC address FF as a regular (not a broadcast) address.
Examples
The following example enables local acknowledgment of SDLC address FF:
stun peer-name xxx.xxx.xxx.xxxstun protocol-group 1 sdlcinterface serial 1encapsulation stunstun group 1stun sdlc-role secondarysdlc address c1sdlc address ff ack-modestun route address c1 tcp yyy.yyy.yyy.yyy local-ackstun route address ff tcp yyy.yyy.yyy.yyy local-ackRelated Commands
stun route address tcp
Specifies TCP encapsulation and optionally establishes SDLC local acknowledgment (SDLC transport) for STUN.
sdlc dte-timeout
Use the sdlc dte-timeout interface configuration command to adjust the amount of time a data terminal equipment (DTE) interface waits for the data circuit-terminating equipment (DCE) to assert a Clear To Send (CTS) signal before dropping a Request To Send (RTS).
sdlc dte-timeout unit
Syntax Description
unit
Timeout wait interval in microseconds. The valid range is 10 to 64000. Each unit is approximately 5 microseconds. The default is 10 units.
Defaults
10 units (approximately 50 microseconds)
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command on an interface that is in half-duplex mode and that has been configured for DTE.
Examples
The following example sets the amount of time that the DTE waits for the DCE to assert a CTS to 100 units (approximately 500 microseconds):
sdlc dte-timeout 100Related Commands
sdlc frmr-disable
Use the sdlc frmr-disable interface configuration command to indicate that secondary stations on a particular serial link do not support Frame Rejects (FRMRs) or error indications. Use the no form of this command to specify that the secondary station does support FRMRs.
sdlc frmr-disable
no sdlc frmr-disable
Syntax Description
This command has no arguments or keywords.
Defaults
Support of FRMRs or error indications
Command Modes
Interface configuration
Command History
Usage Guidelines
FRMRs are error indications that can be sent to an SDLC station indicating that a protocol error has occurred. Not all SDLC stations support FRMRs. If this command is enabled, when the Cisco IOS software receives an error, it drops the line by sending a disconnect request to the remote station.
Examples
In the following example, the software is set to drop the serial line when it receives a protocol error:
interface serial 0sdlc frmr-disableRelated Commands
sdlc holdq
Use the sdlc holdq interface configuration command to control the maximum number of packets that can be held in a buffer before being transmitted to a remote SDLC station.
sdlc holdq address queue-size
no sdlc holdq address queue-size
Syntax Description
address
SDLC address for which you are specifying a queue size.
queue-size
Local send window size. The minimum is 1 packet. No maximum value has been established. The default is 200 packets.
Defaults
200 packets
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is particularly useful with the SDLLC feature that allows an LLC2-speaking SNA station on a Token Ring to communicate with an SDLC-speaking SNA station on a serial link. Frame sizes and window sizes on Token Rings are often much larger than those acceptable for serial links. The fact that serial links are often much slower than Token Rings often makes this problem worse. Therefore, temporary backlogs can exist in periods of high data transfer from the Token Ring station to the serial station. A buffer creates a holding place for backlogged frames awaiting transmission on the serial link. This command is specified for each SDLC address, and therefore, for each SDLC secondary station on the serial link.
Examples
The following example shows how to change the output hold queue length to 30 frames on an SDLC station of address C1 off serial interface 0:
! enter a global command, if you have not alreadyinterface serial 0! use SDLC encapsulationencapsulation sdlc-primary! establish address of SDLC station off serial 0 as c1sdlc address c1! change the output hold queue length to 30 frames on the SDLC stationsdlc holdq c1 30Related Commands
sdlc k
Use the sdlc k interface configuration command to set the window size in order to control the maximum number of information frames the Cisco IOS software transmits before it must stop transmitting and wait for an acknowledgment from the receiving router.
sdlc k window-size
no sdlc k window-size
Syntax Description
window-size
Local send window size. The minimum is 1 frame. The maximum is 7 frames, which is the default.
Defaults
7 frames
Command Modes
Interface configuration
Command History
Usage Guidelines
When the Cisco IOS software is communicating with SDLC, it must have a parameter that controls the maximum number of information frames it will send before it must stop sending and wait for an acknowledgment. The k parameter controls this window of acceptable frames. Use this command in conjunction with the sdlc n1 command to create a balance between frame checking and network performance.
Examples
In the following example, the software can send up to five frames before it must receive an acknowledgment:
! enter a global command, if you have not alreadyinterface tokenring 0!send up to 5 frames, then wait for acknowledgmentsdlc k 5Related Commands
Controls the maximum size of an incoming frame.
Displays the LLC2 connections active in the router.
sdlc line-speed
Use the sdlc line-speed interface configuration command to enable adaptive SDLC T1.
sdlc line-speed rate
no sdlc line-speed rate
Syntax Description
Defaults
No default rate
Command Modes
Interface configuration
Command History
Usage Guidelines
This feature is used to calculate the adjusted SDLC T1 value. The adjusted T1 is used to compensate for the delay between the time the system software passes a packet to the microcode, and the time the packet is actually sent out on the line. For a DCE device, this should be equal to the clockrate on the interface. For a DTE device, it should be equal to the clockrate on the DCE device to which the DTE is connected.
Examples
In the following example, the SDLC line-speed rate is set to rate:
sdlc line-speed rateRelated Commands
sdlc n1
Use the sdlc n1 interface configuration command to control the maximum size of an incoming frame.
sdlc n1 bit-count
Syntax Description
bit-count
Number indicating bit size. Frames that exceed this size are rejected. The minimum is 1 bit. The maximum value depends on the configured maximum MTU value for the interface.
Defaults
12000 bits
Command Modes
Interface configuration
Command History
Usage Guidelines
Use with the sdlc k command to reduce network overhead while continuing to check frame transmission.
The formula for determining the maximum allowed value for the bit-count argument is the maximum MTU value of the interface + 2 bytes (for the SDLC header) multiplied by 8 (to convert from bytes to bits). For example, if the maximum MTU of the interface is 1500 bytes, then the largest value for the bit-count argument is (1500+2)*8=12016 bits. Usually, the default maximum MTU size is 1500 bytes, but it can be configured as high as 18000 bytes.
Examples
In the following example, the Cisco IOS software rejects frames larger than 10000 bits:
interface serial 0sdlc n1 10000Related Commands
sdlc n2
Use the sdlc n2 interface configuration command to determine the number of times that the Cisco IOS software resends a frame before terminating the SDLC session.
sdlc n2 retry-count
no sdlc n2 retry-count
Syntax Description
retry-count
Number of retry attempts. When this number is exceeded, the SDLC station terminates its session with the other station. The minimum is 1 and the maximum is 255. The default is 20 retries.
Defaults
20 retries
Command Modes
Interface configuration
Command History
Usage Guidelines
Use with the sdlc t1 command to reduce network overhead while continuing to check transmission.
Examples
In the following example, the software is set to drop an SDLC station after five unsuccessful attempts to receive an acknowledgment for a frame:
interface serial 0sdlc n2 5Related Commands
Controls the amount of time the Cisco IOS software waits for an acknowledgment to a frame or sequence of frames.
Displays the LLC2 connections active in the router.
sdlc partner
Use the sdlc partner interface configuration command to specify the destination address with which an LLC session is established for the SDLC station. Use the no form of this command to cancel the configuration.
sdlc partner mac-address sdlc-address inbound outbound
no sdlc partner mac-address sdlc-address inbound outbound
Syntax Description
Defaults
No partner is defined.
Command Modes
Interface configuration
Command History
11.0
This command was introduced.
11.2
This command was updated to include the inbound and outbound parameters.
Usage Guidelines
The inbound keyword prevents unwanted messages on the host operator console from inbound XID's to inactive VTAM Switched Major Nodes. It directs SDLC to not send Test or XID frames to the host, FEP, or 3172 even after the connection to a downstream PU2 is complete. The inbound keyword is required for System88 support. The outbound keyword TBD.
Examples
The following example establishes the correspondence between an SDLC and QLLC connection:
sdlc partner 1000.5aed.1f53 d2 inbound outboundRelated Commands
Configures an SDLC interface.
sdlc dlsw
Attaches SDLC addresses to DLSw+.
Configures a MAC address for the serial interface.
sdlc poll-limit-value
Use the sdlc poll-limit-value interface configuration command to control how many times a single secondary station can be polled for input before the next station must be polled. Use the no form of this command to retrieve the default value.
sdlc poll-limit-value count
no sdlc poll-limit-value count
Syntax Description
count
Number of times the Cisco IOS software can poll one secondary station before proceeding to the next station. The minimum is 1 time, which is the default. The maximum is 10 times.
Defaults
1 time
Command Modes
Interface configuration
Command History
Usage Guidelines
As is typical for the primary station of an SDLC connection, if a secondary station sends its full possible window of input to the primary router or access server, the Cisco IOS software immediately will re-poll the same secondary for more data in an attempt to capture the complete transaction at one time. The sdlc poll-limit-value command indicates how many times this can happen before the next station in the poll loop must be polled.
Increasing the value allows for smoother transaction processing but can delay polling of other stations or giving output to other stations.
Examples
The following example specifies that the router can be polled two times before the next station in the poll list must be polled:
! enter a global command, if you have not alreadyinterface serial 4no ip address! use stun encapsulationencapsulation stun! establish stun group 4 on interface serial 4stun group 4stun sdlc-role primary! poll the router up to two times before polling the next stationsdlc poll-limit-value 2Related Commands
sdlc poll-pause-timer
Use the sdlc poll-pause-timer interface configuration command to control how long the Cisco IOS software pauses between sending each poll frame to secondary stations on a single serial interface. Use the no form of this command to retrieve the default value.
sdlc poll-pause-timer milliseconds
no sdlc poll-pause-timer milliseconds
Syntax Description
milliseconds
Number of milliseconds that the software waits before sending the poll frame to a single serial interface. This is a number in the range 1 to 10000. The default is 10 milliseconds.
Defaults
10 milliseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
As is typical for the primary station of an SDLC connection, the software generates polls periodically to each of the secondary stations to solicit their input. After polling each station on a single serial interface, the software will pause before beginning to poll the next station.
Because the secondaries cannot transmit data until they are polled, increasing this timer can increase response time to the users. However, making this parameter too small can flood the serial link with unneeded polls and require the secondary stations to spend wasted CPU time processing them.
Examples
In the following example, the software pauses 2000 milliseconds before sending a series of poll frames through serial interface 4:
! enter a global command, if you have not alreadyinterface serial 4no ip address! use STUN encapsulationencapsulation stun! establish stun group 4 on interface serial 4stun group 4!stun sdlc-role primary! wait 2000 milliseconds before sending each series of poll framessdlc poll-pause-timer 2000Related Commands
Controls how many times a single secondary station can be polled for input before the next station must be polled.
Displays the LLC2 connections active in the router.
sdlc poll-wait-timeout
Use the sdlc poll-wait-timeout interface configuration command when the router has been configured for local acknowledgment and some form of SDLC communication (SDLLC or STUN, for example) to specify the interval the Cisco IOS software will wait for polls from a primary node before timing out that connection.
sdlc poll-wait-timeout milliseconds
no sdlc poll-wait-timeout milliseconds
Syntax Description
Defaults
10000 milliseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
This command can be used on an interface that has been configured as a secondary node, but is not to be used on an interface that has been configured as a primary node.
In a locally acknowledged multidrop environment, the polls the primary node sends to the router can be delayed because the primary node is busy polling other secondary nodes. In such situations, this command can be used to extend the timeout, thus reducing the likelihood the Cisco IOS software times out the connection to the primary node.
Examples
The following example specifies that the local software will wait an interval of 63000 milliseconds for a poll from a primary station before timing out:
! sample stun peer-name global commandstun peer-name 150.136.134.86! sample protocol-group commandstun protocol-group 4 sdlc!interface serial 0! sample ip address commandno ip address! sample encapsulation stun commandencapsulation stun! place interface serial0 in previously defined STUN group 4stun group 4! must enter the next command to use the sdlc poll-wait-timeout commandstun sdlc-role secondary! set timeout period for polls from primary station to 63000 milliseconds.sdlc poll-wait-timeout 63000! list the addresses of the sdlc stations on the linksdlc address C1sdlc address C2! provide stun route commandstun route address C2 tcp 150.136.134.58stun route address C1 tcp 150.136.134.58Related Commands
sdlc qllc-prtnr
To establish correspondence between an SDLC and QLLC connection, use the sdlc qllc-prtnr interface configuration command.
sdlc qllc-prtnr virtual-mac-address sdlc-address
Syntax Description
virtual-mac-address
The virtual Media Access Control (MAC) address in the form h.h.h.
sdlc-address
SDLC address in hexadecimal. The valid range is 1 to FE.
Defaults
No correspondence is defined.
Command Modes
Interface configuration
Command History
Examples
The following example establishes the correspondence between an SDLC and QLLC connection:
sdlc qllc-prtnr 4000.0122.0001 c1Related Commands
sdlc role
Use the sdlc role interface configuration command to establish the router to be either a primary or secondary SDLC station. Use the no form of this command to cancel the designation.
sdlc role {none | primary | secondary | prim-xid-poll}
Syntax Description
Defaults
No default role is assigned.
Command Modes
Interface configuration
Command History
Usage Guidelines
If the role is none, the router can be either primary or secondary, depending on the end stations. The SDLC end station must be configured as negotiable or primary NT2.1. When the end stations are configured as Physical Unit type 2 (PU 2), you can set the role of the interface to primary or secondary. When the end station is configured as secondary NT2.1, you must set the role of the interface to prim-xid-poll.
To configure an SDLC multidrop line (downstream), configure the SDLC role as follows:
•
•
Examples
The following example configures the router as a primary SDLC station:
interface serial 2/6no ip addressencapsulation sdlcfras map sdlc c1 serial 2/0 frame-relay 32 4 4sdlc role primarysdlc address c1sdlc xid c1 01700001Related Commands
sdlc saps
To set up SDLC-to-LLC sessions with respect to the SSAP and DSAP on the LAN-connected device (LLC), use the sdlc saps interface configuration command. To return to the default setting, use the no form of this command.
sdlc saps address ssap dsap
no sdlc saps address ssap dsap
Syntax Description
Defaults
The default value for both the ssap and dsap arguments is 04.
Command Modes
Interface configuration
Command History
Examples
The following example configures SDLC address 01, SSAP 08, and DSAP 08.
sdlc saps 01 08 08sdlc sdlc-largest-frame
Use the sdlc sdlc-largest-frame interface configuration command to indicate the largest information frame (I-frame) size that can be sent or received by the designated SDLC station. Use the no form of this command to return to the default value.
sdlc sdlc-largest-frame address size
no sdlc sdlc-largest-frame address size
Syntax Description
address
Address of the SDLC station that will communicate with the router.
size
Largest frame size that can be sent or received. The default is 265 bytes.
Defaults
The default largest I-frame is 265 bytes.
Command Modes
Interface configuration
Command History
Examples
In the following example, the Cisco IOS software can send or receive a frame as large as 265 bytes (the default) from the SDLC station at address C6. Any frames larger will be fragmented by the software.
interface serial 4sdlc sdlc-largest-frame c6 265sdlc simultaneous
To enable an interface configured as a primary SDLC station to operate in two-way simultaneous mode, use the sdlc simultaneous interface configuration command.
sdlc simultaneous [full-datamode | half-datamode]
no sdlc simultaneous [full-datamode | half-datamode]
Syntax Description
Defaults
Two-way simultaneous mode is disabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
By default, the SDLC driver supports alternative mode. This means that in a multidrop environment, the primary station cannot send data to another secondary station until it receives a response (F bit) from the secondary station with which it is currently communicating.
In contrast, two-way simultaneous mode enables the interface configured as a primary SDLC station to send data to a second secondary station, even when it is receiving data from another secondary station. This capability improves utilization of a full-duplex serial line.
Examples
The following example enables all primary stations to send and receive data at the same time:
sdlc simultaneous full-datamodeThe following example enables all secondary stations to send or receive data at the same time:
sdlc simultaneous half-datamodeRelated Commands
Configures the router as the primary SDLC station if you plan to configure the SDLLC media translation feature.
Displays the LLC2 connections active in the router.
sdlc slow-poll
Use the sdlc slow-poll interface configuration command to enable the slow-poll capability of the router as a primary SDLC station. Use the no form of this command to disable slow-poll capability.
sdlc slow-poll seconds
no sdlc slow-poll
Syntax Description
Defaults
10 seconds
Command Modes
Interface configuration
Command History
Usage Guidelines
You can use this command to improve the performance of a multidropped SDLC configuration when one or more of the secondary stations are inactive.
When slow-poll is enabled, if the router acting as a primary station detects that a secondary SDLC station is not responding, it polls that secondary SDLC station less frequently. The router spends less time waiting for the inactive secondary station to respond, thereby minimizing the performance degradation on the active secondary SDLC stations on the multidropped line.
Examples
The following example enables the slow-poll capability:
interface serial 0sdlc slow-pollRelated Commands
sdlc t1
Use the sdlc t1 interface configuration command to control the amount of time the Cisco IOS software waits for an acknowledgment to a frame or sequence of frames.
sdlc t1 milliseconds
no sdlc t1 milliseconds
Syntax Description
milliseconds
Number of milliseconds that the software waits. The minimum is 1 millisecond and the maximum is 64000 milliseconds. The default is 3000 milliseconds.
Defaults
3000 milliseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
When an SDLC station sends a frame, it waits for an acknowledgment from the receiver that the frame has been received. The sending station cannot wait indefinitely for a response. When the frame is sent, a timer is started. To be consistent with the original specification of SDLC, this timer is called the T1 timer and is controlled by this parameter. If this timer reaches its limit before the acknowledgment is received, the software will try again and resend the frame.
Examples
In the following example, the software waits up to 4000 milliseconds for a reply to a frame or sequence of frames:
! enter a global command, if you have not alreadyinterface tokenring 0sdlc t1 4000Related Commands
Determines the number of times that the Cisco IOS software resends a frame before terminating the SDLC session.
Displays the LLC2 connections active in the router.
sdlc test serial
Use the sdlc test serial EXEC command to determine the status of end stations. Use the sdlc test serial command with the stop keyword to halt the sending of the test frames.
sdlc test serial number address [iterations | continuous | stop | string string]
Syntax Description
Defaults
The sdlc test serial command is not active.
The default test string is "ABCDEFGHIJKLMNOPQRSTUVWXYZ."
Command Modes
EXEC
Command History
Usage Guidelines
The command will pre-check for correct interface and SDLC address. The results of the test frames sent can be viewed after the frames have been sent or an sdlc test serial command with the stop keyword has been issued.
Examples
The following are variations of the sdlc test serial command, followed by the response for each:
Router# sdlc test serial 0 c1SDLC Test for address C1 completedFrames sent=10 Frames received=10Router# sdlc test serial 0 c1 255SDLC Test for address C1 completedFrames sent=255 Frames received=255Router# sdlc test serial 0 C1 stopSDLC Test for address C1 completedFrames sent=44 Frames received=44Router# sdlc test serial 0 c1 string HeyMrPUareyouthereSDLC Test for address C1 completedFrames sent=10 Frames received=10Related Commands
sdlc vmac
Use the sdlc vmac interface configuration command to configure a MAC address for the serial interface. Use the no form of this command to disable the configuration.
sdlc vmac mac-address
no sdlc vmac mac-address
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
This command must be configured if you plan to configure DLSw+. The last byte of the address must be 00.
Examples
The following example specifies a MAC address for the serial interface:
sdlc vmac 1234.3174.0000Related Commands
sdlc xid
Use the sdlc xid interface configuration command to specify an exchange ID (XID) value appropriate for the designated SDLC station associated with this serial interface. Use the no form of this command to disable XID processing for this address.
sdlc xid address xid
no sdlc xid address xid
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
XID requests and responses are usually exchanged before sessions are started. Be sure that the XID value configured in the Cisco IOS software matches the IDBLK and IDNUM parameters configured on the host. The XID response to an XID request will contain the information you configured in the sdlc xid command. The host will check the XID response it receives with the IDBLK and IDNUM parameters (that are configured in the VTAM). If they match, the host will initiate a session with the router. If they do not match, the host will not initiate a session.
Examples
The following example specifies an XID value of 01720002 at address C2:
interface serial 0sdlc xid c2 01720002Related Commands
sdlc xid-pause-timer
To control the frequency of XID retries between a router and an upstream VTAM, use the sdlc xid-pause-timer interface configuration command. To restore the default timer value, use the no form of this command.
sdlc xid-pause-timer time
no sdlc xid-pause-timer time
Syntax Description
time
Length of time the router is to wait, in seconds, before sending the next retry XID. The valid range is 10 to 300 seconds. The default is 10 seconds.
Defaults
The default XID pause timer value is 10 seconds.
Command Modes
Interface configuration
Command History
Usage Guidelines
When a router attempts to send an XID upstream to VTAM, and the switched major node is down, the router continues to send retry XIDs at 10 second intervals. If many other routers are also attempting to send retry XIDs to VTAM, the resulting XID flood can cause problems. The sdlc xid-pause-timer command enables you to control the interval between router XID retries.
Examples
The following example specifies an XID pause timer value of 60 seconds:
interface serial 0sdlc xid-pause-timer 60show llc2
Use the show llc2 privileged EXEC command to display the LLC2 connections active in the router.
show llc2
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
Examples
The following is sample output from the show llc2 command:
Router# show llc2TokenRing0 DTE=1000.5A59.04F9,400022224444 SAP=04/04, State=NORMALV(S)=5, V(R)=5, Last N(R)=5, Local window=7, Remote Window=127ack-max=3, n2=8, Next timer in 7768xid-retry timer 0/60000 ack timer 0/1000p timer 0/1000 idle timer 7768/10000rej timer 0/3200 busy timer 0/9600ack-delay timer 0/3200CMNS Connections to:Address 1000.5A59.04F9 via Ethernet2Protocol is upInterface type X25-DCE RESTARTS 0/1Timers: T10 1 T11 1 T12 1 T13 1The display includes a CMNS addendum, indicating LLC2 is running with CMNS. When LLC2 is not running with CMNS, the show llc2 command does not display a CMNS addendum.
Table 37 describes significant fields shown in the display.
Related Commands