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LLC2 and SDLC Commands

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:

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:

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.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

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.

Example

The following example configures an SDLC interface:

interface serial 2/6
no ip address
encapsulation sdlc
Related Command

sdlc role

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
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already 
interface serial 0
encapsulation sdlc-primary
sdlc address c1
sdlc address c2
Related Commands

encapsulation sdlc-secondary
sdlc address
show interfaces

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
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example establishes the router as a secondary SDLC station:

interface serial 0
encapsulation sdlc-secondary
Related Commands

encapsulation sdlc-primary
sdlc address
show interfaces

llc2 ack-delay-time

Use the llc2 ack-delay-time interface 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
milliseconds Number of milliseconds the software allows incoming information frames to stay unacknowledged. The minimum is
1 ms and the maximum is 60000 ms. The default is 100 ms.
Default

100 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software allows a 100-ms delay before I-frames must be acknowledged:

! enter a global command, if you have not already
interface tokenring 0
! sample ack-max command 
llc2 ack-max 3
! allow a 100 millisecond delay before I-frames must be acknowledged
llc2 ack-delay-time 100

At 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 ms, 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

llc2 ack-max
show llc2

llc2 ack-max

Use the llc2 ack-max interface 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 127 packets. The default is 3 packets.
Default

3 packets

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface tokenring 0
! receive up to seven frames before sending an acknowledgment
llc2 ack-max 7
! sample delay-time command
llc2 ack-delay-time 100
Related Commands

llc2 ack-delay-time
llc2 local-window
show llc2

llc2 idle-time

Use the llc2 idle-time interface configuration command to control the frequency of polls during periods of idle time (no traffic).

llc2 idle-time milliseconds
Syntax Description
milliseconds Number of milliseconds that can pass with no traffic before the LLC2 station sends a Receiver Ready frame. The minimum is 1 ms and the maximum is 60000 ms. The default is 10000 ms.
Default

10000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the Cisco IOS software waits 20000 ms before sending a Receiver Ready ("are you there") frame:

! enter a global command, if you have not already
interface tokenring 0
! wait 20000 ms before sending receiver-ready frames
llc2 idle-time 20000 
Related Commands

llc2 tbusy-time
llc2 tpf-time
show llc2

llc2 local-window

Use the llc2 local-window interface 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 
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.
Default

7 packets

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface tokenring 1
llc2 local-window 30 
Related Commands

llc2 ack-max
show llc2

llc2 n2

Use the llc2 n2 interface 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 
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.
Default

8 retries

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface tokenring 1
! retry value of 8 
llc2 n2 8 
Related Commands

llc2 t1-time
llc2 tbusy-time
llc2 trej-time
show llc2

llc2 t1-time

Use the llc2 t1-time interface 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
milliseconds Number of milliseconds the software waits before resending unacknowledged information frames. The minimum is 1 ms and the maximum is 60000 ms. The default is 1000 ms.
Default

1000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software will wait 4000 ms before resending an unacknowledged frame through Token Ring interface 2:

! enter a global command, if you have not already
interface tokenring 2
! wait 4000 ms before retransmitting a frame through tokenring 2
llc2 t1-time 4000
Related Commands

llc2 n2
llc2 tpf-time
llc2 xid-retry-time
show llc2

llc2 tbusy-time

Use the llc2 tbusy-time interface 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 ms and the maximum is 60000 ms. The default is 9600 ms.
Default

9600 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software will wait up to 12000 ms 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 already
interface tokenring 0
! wait 12000 ms before polling a station through tokenring 0
llc2 tbusy-time 12000
Related Commands

llc2 n2
llc2 idle-time
show llc2

llc2 tpf-time

Use the llc2 tpf-time interface 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 
Syntax Description
milliseconds Number of milliseconds the software waits for a final response to a poll frame before resending the poll frame. The minimum is 1 ms and the maximum is 60000 ms. The default is 1000 ms.
Default

1000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

While you generally will not want to change the transmit-poll-frame time, this example sets the TPF time to 3000 ms. 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 already
interface tokenring 0
! send a poll bit set through tokenring 0 after a 3000 ms delay
llc2 tpf-time 3000 
! wait 1500 ms for an acknowledgment before resending I-frames
llc2 t1-time 1500
Related Commands

llc2 idle-time
llc2 n2
llc2 t1-time
show llc2

llc2 trej-time

Use the llc2 trej-time interface 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
milliseconds Number of milliseconds the software waits for a resend of a rejected frame before sending a reject command to the remote station. The minimum is 1 ms and the maximum is 60000 ms. The default is 3200 ms.
Default

3200 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software will wait up to 1000 ms 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 already
interface tokenring 0
! wait 1000 ms before resending a reject message through tokenring 0
llc2 trej-time 1000 
Related Commands

llc2 n2
show llc2

llc2 xid-neg-val-time

Use the llc2 xid-neg-val-tim interface configuration command to control the frequency of exchange of identification (XID) transmissions by the Cisco IOS software.

llc2 xid-neg-val-time milliseconds 
Syntax Description
milliseconds Number of milliseconds after which the software sends XID frames to other LLC2-speaking stations. The minimum is 0 ms and the maximum is 60000 ms. The default is 0 ms.
Default

0 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example shows how to reset the frequency of XID transmissions to the default of
0 ms:

! enter a global command, if you have not already
interface tokenring 0
! set the frequency of XID transmissions to 0 
llc2 xid-neg-val-time 0 
Related Commands

llc2 xid-retry-time
show llc2

llc2 xid-retry-time

Use the llc2 xid-retry-time interface 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 
Syntax Description
milliseconds Number of milliseconds the software waits for a reply to XID frames before dropping a session. The minimum is 1 ms and the maximum is 60000 ms. The default is 60000 ms.
Default

60000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example sets the software to wait up to 60000 ms 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 already
interface tokenring 0
! wait 60000 ms for a reply to XID frames 
llc2 xid-retry-time 60000 
Related Commands

llc2 t1-time
llc2 xid-neg-val-time
show llc2

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]
no sdlc address hexbyte

Syntax Description
hexbyte Hexadecimal number (base 16) indicating the address of the serial link.
echo (Optional) Treats nonecho and echo SDLC addresses as the same address.
Default

No secondary stations are assigned.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 0
encapsulation sdlc-primary
sdlc address c1
sdlc address c2
Related Commands

encapsulation sdlc-primary
encapsulation sdlc-secondary
show interfaces

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 Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

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 FFas a regular (not a broadcast) address.

Example

The following example enables local acknowledgment of SDLC address FF:

stun peer-name xxx.xxx.xxx.xxx
stun protocol-group 1 sdlc
interface serial 1
encapsulation stun
stun group 1
stun sdlc-role secondary
sdlc address c1
sdlc address ff ack-mode
stun route address c1 tcp yyy.yyy.yyy.yyy local-ack
stun route address ff tcp yyy.yyy.yyy.yyy local-ack
Related Command

A dagger (+) indicates that the command is documented outside this chapter.

stun route address tcp +

sdlc dlsw

Use the sdlc dlsw interface configuration command to attach SDLC addresses to DLSw+. Use the no form of this command to cancel the configuration.

sdlc dlsw sdlc-address sdlc-address ...
no sdlc dlsw sdlc-address sdlc-address ...

Syntax Description
sdlc-address SDLC address in hexadecimal. The valid range is 1 to FE.
Default

No correspondence is defined.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

Example

The following command attaches SDLC address D2 to DLSw+:

sdlc dlsw d2
Related Commands

encapsulation sdlc
sdlc address
sdlc role

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.
Default

10 units (approximately 50 microseconds)

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use this command on an interface that is in half-duplex mode and that has been configured for DTE.

Example

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 100
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

half-duplex +
half-duplex timer +

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 framer-disable

Syntax Description

This command has no arguments or keywords.

Default

Support of FRMRs or error indications

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software is set to drop the serial line when it receives a protocol error:

interface serial 0
sdlc frmr-disable
Related Command

show interfaces

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  
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.
Default

200 packets

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface serial 0
! use SDLC encapsulation
encapsulation sdlc-primary
! establish address of SDLC station off serial 0 as c1
sdlc address c1
! change the output hold queue length to 30 frames on the SDLC station
sdlc holdq c1 30
Related Command

show interfaces

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  
Syntax Description
window-size Local send window size. The minimum is 1 frame. The maximum is 7 frames, which is the default.
Default

7 frames

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface tokenring 0
!send up to 5 frames, then wait for acknowledgment 
sdlc k 5 
Related Commands

sdlc n1
show interfaces

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
rate Clockrate in bits per second.
Default

No default rate

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the SDLC line-speed rate is set to rate:

sdlc line-speed rate
Related Commands

sdlc n2
sdlc t1

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 is 12000 bits, which is the default.
Default

12000 bits

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use with the sdlc k command to reduce network overhead while continuing to check frame transmission.

Example

In the following example, the Cisco IOS software rejects frames larger than 10000 bits:

! enter a global command, if you have not already
interface tokenring 0
! reject frames larger than 10000 bits
sdlc n1 10000 
Related Commands

sdlc k
show interfaces

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  
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.
Default

20 retries

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use with the sdlc t1 command to reduce network overhead while continuing to check transmission.

Example

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 0
sdlc n2 5
Related Commands

sdlc t1
show interfaces

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 
no sdlc partner mac-address sdlc-address 

Syntax Description
mac-address The 48-bit Media Access Control (MAC) address of the Token Ring host.
sdlc-address SDLC address of the serial device that will communicate with the Token Ring host. The valid range is 1 to FE.
Default

No partner is defined.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

Example

The following command establishes the correspondence between an SDLC and QLLC connection:

sdlc partner 1000.5aed.1f53 d2
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

encapsulation sdlc
sdlc dlsw 
+
sdlc vmac

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.
Default

1 time

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

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 already
interface serial 4
no ip address
! use stun encapsulation 
encapsulation stun
! establish stun group 4 on interface serial 4
stun group 4
stun sdlc-role primary
! poll the router up to two times before polling the next station 
sdlc poll-limit-value 2 
Related Commands

sdlc poll-pause-timer
show interfaces

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 ms.
Default

10 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software pauses 2000 ms before sending a series of poll frames through serial interface 4:

! enter a global command, if you have not already
interface serial 4
no ip address
! use STUN encapsulation 
encapsulation stun
! establish stun group 4 on interface serial 4
stun group 4
!
stun sdlc-role primary
! wait 2000 ms before sending each series of poll frames 
sdlc poll-pause-timer 2000
Related Commands

sdlc poll-limit-value
show interfaces

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
Syntax Description
milliseconds Number of milliseconds the software will wait for a poll from the primary station before timing out the connection to the primary station. The minimum is 10 ms and the maximum is 64000 ms. The default is 10000 ms.
Default

10000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example specifies that the local software will wait an interval of 63000 ms for a poll from a primary station before timing out:

! sample stun peer-name global command
stun peer-name 150.136.134.86
! sample protocol-group command
stun protocol-group 4 sdlc
!
interface serial 0
! sample ip address command
no ip address
! sample encapsulation stun command
encapsulation stun
! place interface serial0 in previously defined STUN group 4
stun group 4
! must enter the next command to use the sdlc poll-wait-timeout command
stun sdlc-role secondary
! set timeout period for polls from primary station to 63000 ms.
sdlc poll-wait-timeout 63000
! list the addresses of the sdlc stations on the link
sdlc address C1
sdlc address C2
! provide stun route command
stun route address C2 tcp 150.136.134.58
stun route address C1 tcp 150.136.134.58
Related Commands

sdlc poll-limit-value
sdlc poll-pause-timer

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.
Default

No correspondence is defined.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Example

The following command establishes the correspondence between an SDLC and QLLC connection:

sdlc qllc-prtnr 4000.0122.0001 c1
Related Command

show interfaces

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}
no sdlc role {none | primary | secondary | prim-xid-poll}

Syntax Description
none Establishes the router as either a primary or secondary station, depending on the end stations.
primary Establishes the router as a primary station.
secondary Establishes the router as a secondary station.
prim-xid-poll Establishes the router as a primary station when the end station is configured as a secondary NT2.1.
Default

No default role is assigned.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

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:

Example

The following example configures the router as a primary SDLC station:

interface serial 2/6
no ip address
encapsulation sdlc
fras map sdlc c1 serial 2/0 frame-relay 32 4 4
sdlc role primary
sdlc address c1
sdlc xid c1 01700001
Related Command

encapsulation sdlc

sdlc 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.
Default

The default largest I-frame is 265 bytes.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Example

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 4 
sdlc sdlc-largest-frame c6 265

sdlc 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]
Syntax Description
full-datamode (Optional) Enables the primary station to send data to and receive data from the polled secondary station.
half-datamode (Optional) Prohibits the primary station from sending data to the polled secondary station.
Default

Two-way simultaneous mode is disabled.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

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-datamode

The following example enables all secondary stations to send or receive data at the same time:

sdlc simultaneous half-datamode
Related Commands

encapsulation sdlc-primary
show interfaces

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
seconds Amount of time in seconds.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example enables the slow-poll capability:

interface serial 0
sdlc slow-poll
Related Commands

sdlc poll-limit-value
sdlc poll-pause-timer
show interfaces

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
Syntax Description
milliseconds Number of milliseconds that the software waits. The minimum is 1 ms and the maximum is 64000 ms. The default is 3000 ms.
Default

3000 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

In the following example, the software waits up to 4000 ms for a reply to a frame or sequence of frames:

! enter a global command, if you have not already
interface tokenring 0
sdlc t1 4000 
Related Commands

sdlc n2
show interfaces

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
serial number Serial interface on which the test frame is to be sent out.
address SDLC address (in hexadecimal) of the end station to receive the test frame.
iterations (Optional) Number of test frames to be sent. The valid range is 1 to 25 frames. The default is 10 frames.
continuous (Optional) Sends frames continuously until the sdlc test serial command is issued with the stop keyword.
stop (Optional) Halts the sending of test frames.
string string (Optional) Specifies a string of characters as data within the test frame. If this option is not specified, the default test string is ABCDEFGHIJKLMNOPQRSTUVWXYZ.
Defaults

The sdlc test serial command is not active.

The default test string is "ABCDEFGHIJKLMNOPQRSTUVWXYZ."

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

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.

Sample Displays

The following are variations of the sdlc test serial command, followed by the response for each:

Router# sdlc test serial 0 c1
SDLC Test for address C1 completed
Frames sent=10 Frames received=10
Router# sdlc test serial 0 c1 255
SDLC Test for address C1 completed
Frames sent=255 Frames received=255
Router# sdlc test serial 0 C1 stop
SDLC Test for address C1 completed
Frames sent=44 Frames received=44
Router# sdlc test serial 0 c1 string HeyMrPUareyouthere
SDLC Test for address C1 completed
Frames sent=10 Frames received=10
Related Command

show interfaces

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
mac-address 48-bit MAC address of the Token Ring host.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

This command must be configured if you plan to configure DLSw+. The last byte of the address must be 00.

Example

The following example specifies a MAC address for the serial interface:

sdlc vmac 1234.3174.0000
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

encapsulation sdlc
sdlc dlsw 
+

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
address Address of the SDLC station associated with this interface.
xid XID the Cisco IOS software will use to respond to XID requests the router receives. This value must be 4 bytes (8 digits) in length and is specified with hexadecimal digits.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

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.

Example

The following example specifies an XID value of 01720002 at address C2:

interface serial 0
sdlc xid c2 01720002
Related Command

encapsulation sdlc

show interfaces

Use the show interfaces privileged EXEC command to display the SDLC information for a given SDLC interface.

show interfaces
Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Sample Display

The following is sample output from the show interfaces command for an SDLC primary interface supporting the SDLLC function:

Router# show interfaces
Serial 0 is up, line protocol is up
 Hardware is MCI Serial
 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
 Encapsulation SDLC-PRIMARY, loopback not set
      Timers (msec): poll pause 100 fair poll 500. Poll limit 1
      [T1 3000, N1 12016, N2 20, K 7] timer: 56608 Last polled device: none
      SDLLC [ma: 0000.0C01.14--, ring: 7 bridge: 1, target ring: 10
             largest token ring frame 2052]
SDLC addr C1 state is CONNECT
       VS 6, VR 3, RCNT 0, Remote VR 6, Current retransmit count 0
       Hold queue: 0/12 IFRAMEs 77/22 RNRs 0/0 SNRMs 1/0 DISCs 0/0
       Poll: clear, Poll count: 0, chain: p: C1 n: C1
       SDLLC [largest SDLC frame: 265, XID: disabled]
  Last input 00:00:02, output 00:00:01, output hang never
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  Five minute input rate 517 bits/sec, 30 packets/sec
  Five minute output rate 672 bits/sec, 20 packets/sec
       357 packets input, 28382 bytes, 0 no buffer
       Received 0 broadcasts, 0 runts, 0 giants
       0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
       926 packets output, 77274 bytes, 0 underruns
       0 output errors, 0 collisions, 0 interface resets, 0 restarts
       2 carrier transitions

Table 36 shows the timer fields relevant to all SDLC connections.


Table 36: Timer Fields and Descriptions when SDLC is Enabled
Field Description
Timers (msec): Lists the timers and their current values.
poll pause, fair poll, Poll limit Current values of these timers, as described in the individual command sections in this chapter.
T1, N1, N2, K Current values for these timers, as described in the individual command sections in this chapter.

Table 37 shows other data given for each SDLC secondary station configured to be attached to this interface.


Table 37: SDLC Field Descriptions
Field Description
addr Address of this secondary SDLC station.
state is Current state of this connection. The possible values are:

  • DISCONNECT--No communication is being attempted to this secondary.

  • CONNECT--A normal connect state exists between this router and this secondary.

  • DISCSENT--This router has sent a disconnect request to this secondary and is awaiting its response.

  • SNRMSENT--This router has sent a connect request (SNRM) to this secondary and is awaiting its response.

  • THEMBUSY--This secondary has told this router that it is temporarily unable to receive any more information frames.

  • USBUSY--This router has told this secondary that it is temporarily unable to receive any more information frames.

  • BOTHBUSY--Both sides have told each other that they are temporarily unable to receive any more information frames.

  • ERROR--This router has detected an error, and is waiting for a response from the secondary acknowledging this.

VS

Sequence number of the next information frame this station sends.
VR Sequence number of the next information frame from this secondary that this station expects to receive.
Remote VR Last frame transmitted by this station that has been acknowledged by the other station.
Current retransmit count Number of times the current I-frame or sequence of I-frames has been retransmitted.
Hold queue: Number of frames in hold queue/Maximum size of hold queue.
IFRAMEs, RNRs, SNRMs,

DISCs

Sent/received count for these frames.
Poll: "Set" if this router has a poll outstanding to the secondary; "clear" if it does not.
Poll count: Number of polls, in a row, given to this secondary station at this time.
chain: Shows the previous (p) and next (n) secondary address on this interface in the round robin loop of polled devices.
Related Commands

encapsulation sdlc-primary
encapsulation sdlc-secondary
sdlc frmr-disable
sdlc holdq
sdlc n1
sdlc n2
sdlc poll-limit-value
sdlc poll-pause-timer

show 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 Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Sample Display

The following is sample output from the show llc2 command:

Router# show llc2
TokenRing0 DTE=1000.5A59.04F9,400022224444 SAP=04/04, State=NORMAL
V(S)=5, V(R)=5, Last N(R)=5, Local window=7, Remote Window=127
ack-max=3, n2=8, Next timer in 7768
xid-retry timer 0/60000 ack timer 0/1000
p timer 0/1000 idle timer 7768/10000
rej timer 0/3200 busy timer 0/9600
ack-delay timer 0/3200
CMNS Connections to:
 Address 1000.5A59.04F9 via Ethernet2
 Protocol is up
 Interface type X25-DCE RESTARTS 0/1
 Timers: T10 1 T11 1 T12 1 T13 1

The 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 38 describes significant fields shown in the display.


Table 38: Show LLC2 Field Descriptions
Field Description
TokenRing0 Name of interface on which the session is established.
DTE=1000.5A59.04F9, 400022224444 Address of the station to which the router is talking on this session. (The address is the MAC address of the interface on which the connection is established, except when Local Acknowledgment or SDLLC is used, in which case the address used by the Cisco IOS software is shown as in this example, following the DTE address and separated by a comma.)
SAP=04/04 Other station's and the router's (remote/local) service access point (SAP) for this connection. The SAP is analogous to a "port number" on the router and allows for multiple sessions between the same two stations.
State=NORMAL Current state of the LLC2 session. The possible values are:

  • ADM--Asynchronous Disconnect Mode--A connection is not established, and either end can begin one.

  • SETUP--Request to begin a connection has been sent to the remote station, and this station is waiting for a response to that request.

  • RESET--A previously open connection has been reset because of some error by this station, and this station is waiting for a response to that reset command.

  • D_CONN--This station has requested a normal, expected, end of communications with the remote, and is waiting for a response to that disconnect request.

  • ERROR--This station has detected an error in communications and has told the other station of this. This station is waiting for a reply to its posting of this error.

  • NORMAL--Connection between the two sides is fully established, and normal communication is occurring.

  • BUSY--Normal communication state exists, except busy conditions on this station make it such that this station cannot receive information frames from the other station at this time.

  • REJECT--Out-of-sequence frame has been detected on this station, and this station has requested that the other resend this information.

  • AWAIT--Normal communication exists, but this station has had a timer expire, and is trying to recover from it (usually by resending the frame that started the timer).

  • AWAIT_BUSY--A combination of the AWAIT and BUSY states.

  • AWAIT_REJ--A combination of the AWAIT and REJECT states.

V(S)=5

Sequence number of the next information frame this station will send.
V(R)=5 Sequence number of the next information frame this station expects to receive from the other station.
Last N (R)=5 Last sequence number of this station's transmitted frames acknowledged by the remote station.
Local Window=7 Number of frames this station may send before requiring an acknowledgment from the remote station.
Remote Window=127 Number of frames this station can accept from the remote.
ack-max=3, n2=8 Value of these parameters, as given in the previous configuration section.
Next timer in 7768 Number of milliseconds before the next timer, for any reason, goes off.
xid-retry timer 0/60000.... Series of timer values in the form of next-time/time-between, where "next-time" is the next time, in milliseconds, that the timer will wake, and "time-between" is the time, in milliseconds, between each timer wakeup. A "next-time" of zero indicates that the given timer is not enabled, and will never wake.
CMNS Connections to: List of values that affect the interface if CMNS is enabled.
Address 1000.5A59.04F9 via Ethernet2 MAC address of remote station.
   Protocol is up Up indicates the LLC2 and X.25 protocols are in a state where incoming and outgoing Call Requests can be made on this LLC2 connection.
   Interface type X25-DCE One of X25-DCE, X25-DTE, or X25-DXE (both DTE and DCE).
  RESTARTS 0/1 Restarts sent/received on this LLC2 connection.
  Timers: T10, T11, T12, T13 (or T20, T21, T22, T23 for DTE); these are Request packet timers. These are similar in function to X.25 parameters of the same name.
Related Commands

llc2 ack-delay-time
llc2 ack-max
llc2 idle-time
llc2 local-window
llc2 n2
llc2 t1-time
llc2 tbusy-time
llc2 tpf-time
llc2 trej-time
llc2 xid-neg-val-time
llc2 xid-retry-time

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