Nways Multiprotocol Access Services Software User's Guide Version 3.3

Using the 10/100-Mbps Ethernet Network Interface

This chapter describes how to use the 10/100-Mbps Ethernet interface. It includes the following section:

• "Displaying 10/100-Mbps Ethernet Statistics"
• "Auto-negotiation on the 10/100-Mbps Ethernet Interface"
• "Configuring Values Other than Auto for Duplex"
• "Configurations That May Result in Link Activation Failure on the IBM 2216"
• "Configurations That May Result in Mismatched Duplex Modes During Operation"

Displaying 10/100-Mbps Ethernet Statistics

You can use the interface command from the GWCON environment to display the following statistics.

 
+i 0
                                             Self-Test  Self-Test Maintenance
Net   Net'   Interface   Slot-Port              Passed     Failed      Failed
0     0      Eth/0       Slot: 1   Port: 1           1          0           0
 
  Ethernet/IEEE 802.3 MAC/data-link on 10/100-Ethernet interface
 
  Physical address         002035030008
  PROM address             002035030008
  Actual address           002035030008
  Adapter Level            0                                              
  Configured Duplex:       Auto-Negotiation
  Actual Duplex:           Half Duplex***
  Configured Speed:        Auto-Negotiation
  Actual Speed:            100 Mbps
 
  Input statistics:
   failed, packet too long        0   failed, CRC error            0
   failed, alignment error        0   failed, receive overflow     0
  *receive collision              0  *missed  frame                0
 **frames  filtered               0   receive underrun             0
 
   Output statistics:
   one retry                      0   single collision             0
   multiple collisions            0   failed, transmit underflow   0
   failed, excess collisions      0   failed, loss of carrier      0
   late collisions                0   more than one retry          0
   buffer error                   0   total collisions             0
   excessive deferral             0   deferred                     0
   memory error                   0
 
*  cannot be cleared.
** cleared automatically when read.
*** CAUTION: MAY BE DIFFERENT ON THE SWITCH/HUB PORT. 

These statistics have the following meaning:

Nt

Global network number.

Nt'

This field is for the serial interface card. Disregard the output.

Interface

Interface name and its instance number.

Self-Test: Passed

Number of self-tests that succeeded.

Self-Test: Failed

Number of self-tests that failed.

Maintenance: Failed

Number of maintenance failures.

Physical address

The Ethernet address of the device currently in use. This may be the PROM address or an address overwritten by some other protocol.

PROM address

The permanent unique Ethernet address in the PROM for this Ethernet interface.

Actual address

Adapter level

Configured duplex

The value configured for duplex. Values can be Half Duplex, Full Duplex, or Auto-Negotiation.

Actual duplex

The value at which the adapter is presently operating. It might be different from the value configured, depending on the switch capability. If the adapter is not Up, the value displayed will be Unknown. Otherwise the value can be Half Duplex or Full Duplex.

Whenever the link partner (switch or hub) does not participate during the negotiation phase, *** will follow the actual duplex mode value. When *** is indicated the operational duplex value should be verified on the switch or hub for consistency.

Most hubs (unlike switches) can only support half-duplex mode, and are not capable of negotiation. As such the *** indication will usually be displayed when the interface is connected to a hub.

A message will also be logged via the ELS system whenever a possibility of a mis-match in duplex mode exists.

Note:

If the link partner (switch or hub) to which the interface is connected does not respond during the negotiation phase, the two may result in operating in different duplex modes. That is, the interface may be operating in half-duplex, while the switch port is operating in full duplex mode. A mismatch in the duplex mode can result in severe performance degradation. See "10/100-Mbps Ethernet Configuration Commands" for important information regards speed and duplex configurations.

Configured speed

The value configured for speed. Values can be 10 Mbps, 100Mbps, or Auto-Negotiation.

Actual speed

The speed at which the adapter is presently operating.If the adapter is not Up, the value displayed will be Unknown. Otherwise the value can be 10 Mbps or 100 Mbps.

Input statistics:

failed, packet too long or failed, frame too long

The Failed, Packet Too Long counter increments when the interface receives a packet that is larger than the maximum size of 1518 bytes for an Ethernet frame. This data is exported via SNMP as the dot3StatsFrameTooLongs counter.

failed, CRC error or failed, FCS (Frame Check Sequence) error

The Failed, CRC (Cyclic Redundancy Check) Error counter increments when the interface receives a packet with a CRC error. This data is exported via SNMP as the dd3StatsFCSErrors counter.

failed, alignment error

The Failed, Framing Error counter increments when the interface receives a packet where the length in bits is not a multiple of eight.

failed, receive overflow

Overflow error indicates that the receiver has lost all or part of the incoming frame, due to an inability to move data from the receive FIFO into memory buffer before the internal FIFO overflowed.

receive collision

Indicates the total number of collisions encountered by the receiver support on the adapter.

Note:

This counter cannot be cleared by the clear statistics command because it is maintained on the adapter. The test network command is the only way to reset this counter.

missed frame

Indicates the number of incoming receive frames lost due to unavailability of a receive buffer in the system. This error indicates that the system is not processing received frames as fast as they are being received from the local network.

Note:

This counter cannot be cleared by the clear statistics command because it is maintained on the adapter. The test network command is the only way to reset this counter.

frames filtered

Indicates the number of incoming frames that were discarded by the adapter. This counter is updated only when bridging is enabled.

Note:

This counter is maintained on the adapter, and is cleared every time it is read. This counter will be cleared by the interface statistics and the test network commands.

receive underrun

Indicates the number of times the adapter did not have a second buffer to store a long frame (requiring more than one buffer).

Output statistics:

one retry

Indicates that exactly one retry was needed to transmit a frame. This data is exported via SNMP as the dot3StatsDeferredTransmissions counter.

single collision

The Single Collision counter increments when a packet has a collision on the first transmission attempt, and then successfully sends the packet on the second transmission attempt. This data is exported via SNMP as the dot3StatsSingleCollisionFrames counter.

multiple collisions

The Multiple Collisions counter increments when a packet has multiple collisions before being successfully transmitted. This data is exported via SNMP as the dot3MultipleCollisionFrames counter.

failed, transmit underflow

Transmit underrun indicates that transmitter has truncated a message because it could not read data from the memory fast enough. It also indicates that the FIFO on the adapter has emptied out before the end of the frame was reached. IFO into memory buffer before the internal FIFO overflowed.

failed, excess collisions

The Failed, Excess Collisions counter increments when a packet transmission fails due to 16 successive collisions. This error indicates a high volume of network traffic or hardware problems with the network. This data is exported via SNMP as the dot3StatsExcessiveCollisions counter.

failed, loss of carrier

Loss of carrier is set when the carrier is lost during transmission. The adapter does not retry upon loss of carrier. It will continue to transmit the whole frame until done.

late collisions

A late collision indicates that a collision has occurred after the first channel slot time has elapsed. The adapter does not retry on late collisions.

more than one retry

More than one retry indicates that more than one retry was needed to transmit a frame.

buffer error

Buffer error occurs if there is a memory corruption problem in the system, or under certain FIFO underflow conditions on the adapter.

total collisions

The Total Collisions counter increments by the number of collisions a packet incurs.

excessive deferral

Excessive deferral indicates that the transmitter on the adapter has experienced Excessive Deferral on this a transmit frame, where Excessive Deferral is defined in the ISO 8802-3 (IEEE/ANSI 802.3) standard.

deferred

Deferred indicates the number of times the adapter had to defer while trying to transmit a frame. This condition occurs if the DMA channel is busy when the adapter is ready to transmit.

memory error

Memory errors occur when the adapter is not given access to the system interface bus within the programmable length of time. This error will normally occur during transmit operations, indicating transmit underrun.

Auto-negotiation on the 10/100-Mbps Ethernet Interface

Specifying values other than auto for speed or duplex on the 10/100 Ethernet interface or its link partner (switch port) can result in duplex mode mismatch or link activation failures.

Link activation failures due to configuration mismatches will occur on the IBM 2216 whenever the speed configured at both ends are not identical.

When either speed or duplex value is auto-negotiate, both speed and duplex will be negotiated with the link partner and its configured speed or duplex will be used.

Configuring Values Other than Auto for Duplex

The IBM 2216 10/100-Mbps Ethernet interfaces will alert you whenever there is a possibility of a mismatch in the duplex mode between the switch and the router. When auto-negotiation is not configured on both ends, there is no definite way for either end to determine the duplex mode in use at the remote end, and the switch and the router interface can be operating with non-identical duplex modes.

Depending on the switch implementation, the switch port may operate at half duplex, when you have configured full duplex. As such, there is always a possibility of a mismatch to occur between the switch port and the router interface. The IBM 2216 will alert you whenever there is such a possibility, but some switches do not give such an indication.

Configurations That May Result in Link Activation Failure on the IBM 2216

The primary cause of the link activation failure is mis-atched speeds.

To avoid link activation failure, configure auto for speed and duplex on the IBM 2216 and the switch port.

Note:

These results may vary depending on the switch manufacturer and model.

Table 35. Configurations That May Result in Link Failure on the IBM 2216

IBM 2216	Hub/Switch
Auto 10	HDX* 100
Auto 10	FDX* 100
Auto 100	HDX 10
Auto 100	FDX 10
HDX 10	HDX 100
HDX 10	FDX 100
HDX 100	HDX 10
HDX 100	FDX 10
FDX 10	HDX 100
FDX 10	FDX 100
FDX 100	HDX 10
FDX 100	FDX 10

* HDX = Half Duplex   FDX = Full Duplex

Configurations That May Result in Mismatched Duplex Modes During Operation

The primary cause of the mismatched duplex modes is the disabling of auto-negotiation on the switch port and/or the IBM 2216 interface.

To avoid mismatches in duplex mode, configure auto for speed and duplex on the IBM 2216 and the switch port.

Note:

These results may vary depending on the switch manufacturer and model.

Table 36. Configurations That May Result in Mismatched Duplex Modes During Operation

Configuration		Result
IBM 2216	Hub/Switch	IBM 2216	Hub/Switch
Auto Auto	FDX* 10	HDX* 10	FDX 10
Auto Auto	FDX 100	HDX 100	FDX 100
HDX Auto	FDX 10	HDX 10	FDX 10
HDX Auto	FDX 100	HDX 100	FDX 100
Auto 10	FDX 10	HDX 10	FDX 10
Auto 100	FDX 100	HDX 100	FDX 100
HDX 10	FDX 10	HDX 10	FDX 10
FDX Auto	HDX 10	FDX 10	HDX 10
FDX Auto	HDX 100	FDX 100	HDX 100
HDX 100	FDX 100	HDX 100	FDX 100
FDX 10	HDX 10	FDX 10	HDX 10
FDX 100	HDX 100	FDX 100	HDX 100

* HDX = Half Duplex   FDX = Full Duplex