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Using Token Ring Interfaces

This document describes the Token Ring configuration and monitoring commands. It includes

Displaying the Token Ring Prompts

To display the TKR config> prompt,

1. Enter list interfaces at the Config> prompt to display a list of interfaces.

2. Enter network followed by the number of the Token Ring interface.

Config>network
What is the network number [0]? 2
Token-Ring interface configuration

TKR config>

To display the TKR> prompt,

1. Enter interface at the Monitor> prompt to display a list of interfaces configured on the router.

2. Enter network followed by the number of the Token Ring interface.

Monitor>network 2
TKR>

Token Ring Commands

Table 1 summarizes and the following sections explain the Token Ring commands.

Press Space twice after you type a command to display the available parameters for each command for your router. Enter help for information about using the command line interface.

[C] means the command is available at the TKR config> prompt.

[M] means the command is available at the TKR> prompt.

Table 1 Token Ring Commands

Command Function

Dump [M] Displays a dump of the RIF cache.

Exit [C] [M] Returns to the previous prompt.

List [C] Displays the selected Token Ring interface configuration.

LLC [C] [M] Displays the LLC configuration or monitoring prompt.

Media [C] Sets the media-type as shielded or unshielded.

Packet-Size [C] Changes packet-size for all Token Ring networks.

Set [C] Sets the aging timer for the RIF cache and the MAC address.

Source-routing [C] Enables or disables source-routing on the interface.

Speed [C] Sets the interface speed in MB/sec.

SRT-STAT [M] Displays statistical information for transparent bridging.

Table 1 Token Ring Commands
Command	Function
Dump [M]	Displays a dump of the RIF cache.
Exit [C] [M]	Returns to the previous prompt.
List [C]	Displays the selected Token Ring interface configuration.
LLC [C] [M]	Displays the LLC configuration or monitoring prompt.
Media [C]	Sets the media-type as shielded or unshielded.
Packet-Size [C]	Changes packet-size for all Token Ring networks.
Set [C]	Sets the aging timer for the RIF cache and the MAC address.
Source-routing [C]	Enables or disables source-routing on the interface.
Speed [C]	Sets the interface speed in MB/sec.
SRT-STAT [M]	Displays statistical information for transparent bridging.

Dump [M]

When you enable source routing on the Token Ring interface, dump requests a dump of the RIF cache contents. The dump command applies to protocols only. It does not apply to DLSw or bridging.

Syntax: dump

Example: TKR>dump

MAC address     State     Usage     RIF
0000C90B1A57    ON_RING   Yes       0220


MAC address	MAC address of the Token Ring interface.
State	Displays one of the following states: On_ring— a RIF was found for a node on the ring. Have_route— a RIF was found for a node on a remote ring. No_route— displayed for a brief period of time as an explorer frame is sent out and the router is waiting for a return. Discovering— the router sent an explorer frame to rediscover the RIF. St_route— a route obtained from a Spanning tree explorer.
Usage	A RIF was used in a packet. The number is arbitrary and has no functional significance.
RIF	Displays a code that indicates the RIF in hexadecimal.

Exit [C] [M]

Returns to the previous prompt.

Syntax: exit

Example: exit

List [C]

Displays the current configuration for the Token Ring interface.

Syntax: list

Example: list

Token Ring configuration:

Packet size (INFO field:     2052
Speed:                       16 Mb/sec
Media:                       Unshielded

RIF Aging Timer              120
Source Routing:              Disabled
MAC Address:                 000000000000

LLC [C] [M]

Displays the LLC configuration prompt (LLC config>) or monitoring prompt (LLC>). LLC configuration is required to pass packets over an SNA network. See LLC Commands for a description of these commands.

Syntax: llc

Example: llc

LLC user configuration

LLC config>

Media [C]

Changes the network media type. The default is shielded twisted pair. The options are shielded and unshielded.

Some routers also provide auto-config as a media option. This option automatically selects the media type.

Syntax: media shielded or unshielded

Example: media unshielded

Packet-Size [C]

Changes packet-size for all Token Ring networks. Changing packet size can greatly increase buffer memory requirements.

Table 2 shows valid packet sizes for 4 Mbps and 16 Mbps networks.

Table 2 Valid Token Ring Packet Sizes

Speed Values (# of bytes)

4 Mbps
1470, 2052, 4399*

16 Mbps
1470, 2052, 4399
8130, 11407, 17749

*Configuring a packet size greater than 4399 forces
the software to set the packet size at 4399.

Table 2 Valid Token Ring Packet Sizes
Speed	Values (# of bytes)
4 Mbps	1470, 2052, 4399*
16 Mbps	1470, 2052, 4399 8130, 11407, 17749
*Configuring a packet size greater than 4399 forces the software to set the packet size at 4399.

Syntax: packet-size

Example: packet-size

Packet (MSDU) size(1470,2052,4399,8130,11407, 17749)[2052]? 4399

Set [C]

Sets the Routing Information Field (RIF) timer and the physical (MAC) address.

Syntax: set

physical-address
rif-timer

physical address address

Sets the MAC address that is placed in the RIF by nodes running DNA phase IV with AMA. Entering zero (0) causes the router to use the factory station address. The default is to use the factory station address.

Example: set physical-address

MAC address in 00:00:00:00:00:00 []?

rif-timer # of seconds

Amount of time in seconds the router maintains information in the RIF before it is refreshed. The default is 120.

Example: set rif-timer

RIF aging timer value [120]?  120

Source-routing [C]

Enables or disables end station source routing. This is the process by which end stations determine the source route to use to cross source routing bridges. It allows the IP, IPX, and AppleTalk to reach nodes on the other side of the source routing bridge.

This switch is completely independent of whether this interface is providing source routing via the SRT forwarder. The default is enabled.

Some stations cannot properly receive frames with a Source Routing RIF on them. This is especially common among NetWare drivers. Disabling source routing in this situation allows you to communicate with these stations.

You should enable source routing only if there are source routing bridges on this ring through which you want to bridge IP, IPX, or AppleTalk packets.

Syntax: source-routing

enable
disable

Example: source-routing enable

Speed [C]

Changes the data speed. The options are 4 or 16. The default speed is 4 Mbps. Although you can enter this command for all Token Ring interfaces, the software accepts only entries for ProNET-4/16 interfaces.

Syntax: speed Mbps

Example: speed 16

SRT-STAT [M]

Displays information specific to transparent bridging configured on this interface. Srt-stat applies only to hardware that contains Content Addressable Memory (CAM) chips.

Syntax: srt-stat

Example: srt-stat

LLC Commands

LLC configuration is required to pass packets over an SNA network. Enter configuration commands at the LLC config> prompt, which you display by entering llc at the TKR config> prompt. Enter monitoring commands at the LLC> prompt, which you display by entering llc at the TKR> prompt.

Table 3 summarizes and the following sections explain the LLC commands.

Table 3 LLC Commands

Command Function

Clear-Counters [M] Clears all statistical counters.

Exit [C] [M] Returns to the previous prompt.

List [C] [M] Displays the selected LLC configuration. At monitoring prompt, displays interface, SAP, and session information.

Set [C] [M] Sets the timers associated with LLC, and the size of the transmit and receive windows.

Table 3 LLC Commands
Command	Function
Clear-Counters [M]	Clears all statistical counters.
Exit [C] [M]	Returns to the previous prompt.
List [C] [M]	Displays the selected LLC configuration. At monitoring prompt, displays interface, SAP, and session information.
Set [C] [M]	Sets the timers associated with LLC, and the size of the transmit and receive windows.

Clear-Counters [M]

Clears all the LLC statistical counters.

Syntax: clear-counters

Example: clear-counters

Exit [C] [M]

Returns to the previous prompt.

Syntax: exit

Example: exit

List [C] [M]

Displays information at the configuration and monitoring prompts as described below.

List [C]

Displays the current LLC configuration.

Syntax: list

Example: list

Reply Timer (T1):                 1 seconds
Receive ACK Timer (T2):           100 milliseconds
Inactivity Timer (Ti):            30 seconds
Max Retry value (N2):             8
Rcvd I-frames before ACK (N3):    1
Transmit Window (Tw):             2
Receive Window (Rw):              2
Acks needed to increment Ww (Nw): 1

List [M]

At the monitoring prompt, list displays interface, service access point (SAP), and session information.

Syntax: list

interface
sap
session

interface

Displays all SAPs opened on this interface.

Example: list interface

SAP     Number of Sessions
F4      1

SAP sap_number

Displays information for the specified SAP on the interface.

Example: list sap

SAP value in hex (0-FE) [1]? F4

Interface                     0, TKR/0
Reply Timer (T1)              1 sec
Receive ACK Timer (T2)        100 millisec
Inactivity Timer (Ti)         30 sec
MAX Retry Value (N2)          8
MAX I-Field Size (N1)         2052
Rcvd I-frames before ACK (N3) 1
Transmit Window Size (Tw)     2
Acks Needed to Inc Ww (Nw)    1

Frame              Xmt        Rcvd
UI-frames          4          5
TEST-frames        0          1
XID-frames         0          0
I-frames           291        26
RR-frames          81         291
RNR-frames         0          0
REJ-frames         0          0
SABME-frames       1          0
UA-frames          0          1
DISC-frames        0          0
DM-frames          0          0
FRMR-frames        0          0
I-frames discarded by LLC                 0
I-frames Refused by LLC user              0
Cumulative number of sessions             1
Number of active sessions                 1

Session ID                                       Remote
(int-sap-id) Local MAC          Remote MAC         SAP     State
00-F4-0000   00:00:C9:08:41:DB  10:00:5A:F1:02:37   F4     OPENED


SAP value in hex (0-FE)	The SAP value of the session.
Interface	The interface number and type over which the session is running.
Reply Timer (T1)	Time it takes for this timer to expire when the LLC fails to receive an acknowledgment or response from the other LLC station.
Receive ACK Timer (T2)	Time delay the LLC uses before sending an acknowledgment for a received I-frame.
Inactivity Timer (Ti)	Time the LLC waits during inactivity before issuing an RR.
MAX Retry Value (N2)	Maximum number of retries by the LLC protocol.
MAX I-Field Size (N1)	Data (in bytes) allowed in the I-field of an LLC2 frame.
Rcvd I-frame before ACK (N3)	Value that is used with T2 timer to reduce acknowledgment traffic for received I-frames.
Transmit Window Size (Tw)	I-frames that can be sent before receiving an RR.
Acks Needed to Inc Ww (Nw)	I-frames that the LLC must receive before incrementing Ww by 1.
Frames-Xmt and Rcvd	Frame types transmitted (Xmt) and (Rcvd).
I-frames discarded by LLC	I-frames discarded by the LLC, usually because the sequence number is out of sequence.
I-frames refused by LLC user	I-frames discarded by the software above the LLC. For example, LNM (LAN Network Manager) and DLSw (Data Link Switching).
Cumulative number of sessions	Sessions that were opened over this SAP.
Number of active sessions	Currently active sessions running over the interface.
Session ID (int-sap-id)	Session ID for the interface.
Local MAC	Router's LLC MAC address.
Remote MAC	Remote router's LLC MAC address.
Remote SAP	Remote router's SAP address for the LLC connection.
Remote State	The finite state(s) that results from interaction between the LLC peers. There are 21 states that are described below. Link_Closed— The remote LLC peer is not known to the local LLC peer and is considered as not existing. Disconnected— The local LLC peer is known to the other peer. This LLC peer can send and receive XID, TEST, SABME, and DISC commands; and XID TEST, UA, and DM responses. Link_Opening— The state of the local LLC peer after sending a SABME or UA in response to a received SABME. Disconnecting— The state of the local LLC after sending a DISC command to the remote LLC peer. FRMR_Sent— The local LLC peer has entered the frame reject exception state and has sent a FRMR response across the link. Link_Opened— The local LLC peer is in the data transfer phase. Local_Busy— The local LLC peer is unable to receive additional I-frames. Rejection— A local LLC peer has received one or more out-of-sequence I-frames.
	Checkpointing— The local LLC peer has sent a poll to the remote LLC peer and is waiting for an appropriate response. CKPT_LB— Combination of checkpointing and local busy states. CKPT_REJ— Combination of checkpointing and rejection states. Resetting— The local LLC peer has received a SABME and is re-establishing the link. Remote_Busy— An RNR was received from the remote LLC peer. LB_RB— Combination of local_busy and remote_busy states. REJ_LB— Combination of rejection and local_busy states. REJ_RB— Combination of rejection and remote_busy states. CKPT_REJ_LB— Combination of checkpointing, rejection, and local_busy states. CKPT_CLR— Combination state resulting from the termination of a local_busy condition while the LLC peer is CKPT_LB. CKPT_REJ_CLR— A combination state resulting from the transfer of an unconfirmed local busy clear while the link station is in the CKPT_REJ_LB state. REJ_LB_RB— A combination of the rejection, local_busy, and remote_busy states. FRMR_Received— The local LLC peer has received an FRMR response from the remote LLC peer.

session

Displays information on the specified LLC session that is open on the interface.

Example: list session

Session Id: [0]? 00-F4-0000
Interface                     0, TKR/0
Remote MAC addr               10:00:5A:F1:02:37
Source MAC addr               00:00:C9:08:35:47
Remote SAP                    F4
Local SAP                     F4
RIF                           (089E 0101 0022 0010)
Access Priority               0
State                         LINK_OPENED
Replay Timer                  1 sec
Receive ACK Timer (T2)        100 millisec
Inactivity Timer (Ti)         80 sec
MAX I-Field Size (N1)         2052
MAX Retry Value (N2)          8
Rcvd I-frames before ACK (N3) 1
Transmit Window Size (Tw)     2
Working Transmit Size (Ww)    2
Acks Needed to Inc Ww (Nw)    1
Current Send Seq (Vs)         9
Current Rcv Seq (Vr)          7
Last ACK'd sent frame (Va)    9
No. of frames in ACK pend q   0
No. of frames in Tx pend q    0
Local Busy                    NO
Remote Busy                   NO
Poll Retry count              8
Appl output flow stopped      NO
Send process running          YES

Frame           Xmt            Rcvd
I-frames        1456           2678
RR-frames       502             403
RNR-frames      0               0
REJ-frames      0               0 
I-frames discarded by LLC                 0
I-frames Refused by LLC user              0


Session Id	Session ID number.
Interface	Interface over which this session is running.
Remote MAC addr	MAC address of the remote LLC peer.
Source MAC addr	MAC address of the local LLC.
Remote SAP	Remote router's SAP address for the LLC connection.
Local SAP	Local router's SAP for the LLC connection.
RIF	RIF of the frame.
Access Priority	Priority of the packet. 0-7 for upper layer control.
State	The finite state(s) that results from interaction between the LLC peers. See list sap for more information.
Receive ACK timer (T2)	Time delay the LLC uses before sending an acknowledgment for a received I-frame.
Inactivity timer (Ti)	Time the LLC waits during inactivity before issuing an RR.
MAX I-field size (N1)	Maximum size of the data field (in bytes) of a frame. Default is the size of the interface.
MAX Retry Value (N2)	Number of times the LLC transmits an RR without receiving an acknowledgment
Rcvd I-frames before ACK (N3)	Value that is used with T2 timer to reduce acknowledgment traffic for received I-frames.
Transmit window size (Tw)	Number of I-frames that can be sent before receiving an RR.
Working transmit size (Ww)	Number of I-frames that are sent before receiving an RR. This can be less than Tw during the dynamic window algorithm.
Acks Needed to Inc Ww (Nw)	Number of I-frames that the LLC must receive before incrementing Ww by 1.
Current send seq (Vs)	Send state variable (Ns value for the next I-frame to be transferred).
Current Rcv seq (Vr)	Receive state variable (next in-sequence Ns to be accepted).
Last ACK'd sent frame (Va)	Acknowledged state variable (last valid Nr received).
No. of frames in ACK pend q	Transmitted I-frames waiting for acknowledgment.
No. of frames in transmit pend q	Number of frames waiting to be transmitted.
Local Busy	The local router's LLC connection is sending RNRs.
Remote Busy	The remote router's LLC is receiving RNRs.
Poll Retry count	Current value of the retry of the counter (counts down) in the LLC protocol.
Appl output flow stopped	LLC has told the application to stop giving it outgoing data frames.
Send process running	This process runs concurrently with all other frame actions and takes I-frames in the transmit queue and sends them.
Frames -Xmt and Rcvd	Displays the total number of frame types transmitted (Xmt) and (Rcvd).
I-frames discarded by LLC	I-frames discarded by the LLC, usually because the sequence number is wrong.
I-frames refused by LLC user	I-frames discarded by the software above the LLC. For example, LNM (LAN Network Manager) and DLSw (Data Link Switching).

Set [C] [M]

Configures the LLC. At the monitoring prompt, dynamically configures the LLC parameters on the current LLC session. Changes that you make are effective for the life of session.

CAUTION:
Changing LLC parameters from the defaults can affect how the LLC protocol works.

Syntax: set

n2-max-retry
n3-frames-rcvd-before-ack
nw-acks-to-inc-window
rw-receive-window
t1-reply-timer
t2-receive-ack-timer
ti-inactivity-timer
tw-transmit-window

n2-max-retry value

Maximum number of times the LLC transmits an RR without receiving an acknowledgment when the inactivity timer expires. The range is 1 to 127. The default is 8.

Example: set n2-max-retry

Max Retry value (N2) [8]?

n3-frames-rcvd-before-ack value

This counter works with the T2 timer to reduce acknowledgment traffic for received I-frames. Each time the router receives an I-frame, this value decreases by one. When this counter reaches 0 or when the T2 timer expires, the router sends an acknowledgment The range is 1 to 255. The default is 1.

Example: set n3-frames-rcvd-before-ack

Number I-frames received before sending ACK(N3) [1]?

rw-receive-window value

Maximum number of unacknowledged sequentially numbered I-frames that an LLC can receive from a remote LLC peer. This value must be equal to or less than 127. This parameter is not available at the LLC monitoring prompt.

Example: set rw-receive-window

Receive Window (Rw), 127 Max. [2]?

nw-acks-to-inc-ww value

When the ability to send I-frames is not working, LLC goes into a mode where the working window (Ww) is set back to 1, and then slowly increased back to its normal size (Tw). This is known as the dynamic window algorithm. This value is the number of I-frames that the LLC must receive before incrementing Ww by 1. The range is 1 to 127. The default is 1.

Example: set nw-acks-to-inc-ww

Acks needed to increment Ww (Nw) [1]?

t1-reply-timer #-of-seconds

This timer expires when the LLC fails to receive a required acknowledgment or response from the other LLC station. When this timer expires, an RR is sent with the poll bit set and T1 is started again. If the LLC receives no response after the configured maximum number of retries (N2), the link underneath is declared inoperative. The range is 1 to 256. The default is 1.

Example: set t1-reply-timer

Reply Timer (T1) in sec. [1]?

t2-receive-ack-timer #-of-milliseconds

Delays acknowledging an I-format frame. This timer starts when the router receives an I-frame, and it is reset when the router sends an acknowledgment. If this timer expires, LLC2 sends an acknowledgment as soon as possible. Set t2-receive-ack-timer to a value less than t1-inactivity-timer to insure that the remote LLC2 peer receives the delayed acknowledgment before the T1 timer expires. The range is 1 to 2560. The default is 1 (100 ms), which disables the timer.

Example: set t2-receive-ack-timer

Receive Ack timer (T2) in 100 millisec. [1]?

ti-inactivity-timer #-of-seconds

This timer expires when the LLC does not receive a frame for a specified time period. When this timer expires, the LLC transmits an RR until the other LLC responds or the N2 retry count is exceeded. The range is 1 to 256. Default is 30 seconds.

Example: set ti-inactivity-timer

Inactivity Timer (Ti) in sec. [30]?

tw-transmit-window value

Maximum number of I-frames that the router can send before receiving an RR. If the other end of the LLC session can receive this many consecutive I-frames, and the router has enough heap memory to keep copies of these frames until it receives an acknowledgment, increasing this value may increase the throughput. The range is 1 to 127. The default is 2.

Example: set tw-transmit-window

Transmit Window (Tw), 127 Max. [2]?

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