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Voice, IP, and ATM MPLS Features

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: May 17, 2002.

Commands for Verifying Voice Connections

This section describes the commands you use to verify voice connections in the MGX network:

  • tstcon—Tests a connection's continuity

  • tstdelay—Tests a connection's continuity and the round-trip delay

  • dspconcnt—Lists a channel's statistics counters

  • dspmngcidcnt—Lists an endpoint's managed CID counters

Test Connection Command

The tstcon command tests continuity on MGX network connections. If connection segments are failed or misconfigured, the tstcon command fails. The tstcon command does not test quality of service or connectivity beyond the MGX network.

Here is the tstcon command syntax:

tstcon <channel number>

The tstcon command has some limitations:

  • It works only for local connections or connections in a tiered MGX network with BPX or MGX 8850-PXM45 backbone switches.

  • It should be issued from both ends to completely verify connectivity.

  • A passing result of the test does not guarantee the connection's end-to-end performance.

Test Delay Command

The tstdelay command is similar to the tstcon command in that it checks connection continuity. The tstdelay command also measures the round-trip delay through the network. The results are output on the CLI. The most recent delay measurement is also reported in the dspcon output.

Here is the tstdelay command syntax:

tstdelay <channel number>

The tstdelay output is shown in Example 22-12.

Example 22-12 tstdelay Output

smoke.1.3.VISM8.a > tstdelay 131

test type is..... 2

TestDelay in progress.

TestDelay Passed with 54 us.


The limitations on the tstcon command also apply to the tstdelay command.

Display Connection Count Command

The dspconcnt command lists historical connection statistics counters on the VISM. Use this command to learn how much traffic has been sent, received, or dropped on the voice connection. The cells reported in the dspconcnt output are counted at the segmentation and reassembly (SAR) processor in the VISM. Example 22-13 shows the dspconcnt output.

Example 22-13 dspconcnt Output

smoke.1.3.VISM8.a > dspconcnt 131

ChanNum:          131
Chan State:        okay
Chan XMT ATM State:    Normal
Chan RCV ATM State:    Normal
OAM Lpb Lost Cells:         0
AAL2 HEC Errors:          0
AAL2 CRC Errors:          0
AAL2 Invalid OSF Cells:       0
AAL2 Invalid Parity Cells:     0
AAL2 CPS Packet Xmt:        70327
AAL2 CPS Packet Rcv:        124971
AAL2 Invalid CID CPS:        0
AAL2 Invalid UUI CPS:        0
AAL2 Invalid Len. CPS:       0
AAL5 Invalid CPI:          0
AAL5 oversized SDU PDU:       0
AAL5 Invalid Len. PDU:       0
AAL5 PDU CRC32 Errors:       0
AAL5 Reassembly Timer expired PDU: 0

The dspconcnt output shows the following information:

  • Channel state—okay or failed.

  • Channel transmit ATM state—The channel state as reported to the ATM network and the remote end of the connection. For example, if the local line fails, the connection sends Operation, Administration, and Maintenance (OAM) alarm indicator signal (AIS) cells to the remote end (VISM or ATM interface) of the connection.

  • Channel receive ATM state—The channel state reported from the ATM network.

  • OAM loopback lost cells—The number of cells dropped while an OAM loopback was in progress.

  • HEC errors—The number of cells with incorrect header error check (HEC) values.

  • CRC errors—Cyclic Redundancy Check errors. This is a process that is used to check the integrity of a block of data. CRC is a common method of establishing that data was received correctly.

  • Invalid OSF cells—The number of cells with an invalid offset field (OSF) in the start field of the common part sublayer protocol data unit (CPS-PDU).

  • Invalid CID CPS—The number of cells with invalid CIDs in the CPS packet header.

  • Invalid UUI CPS—The number of cells with invalid User-to-User Interface (UUI) fields in the CPS packet header.

  • Invalid length—The number of cells with a payload length that does not match the length indicator (LI) in the CPS packet header.

  • Invalid CPI—Invalid computer-to-PBX interface.

  • Length Indicator (LI)—The number of cells with a payload length that does not match the LI in the CPS packet header.

  • Sequence Number (SN)—The order in which the queues are serviced. It is strongly recommended that you do not change this value. 1 to 16.

  • Parity (P)—The process of detecting whether bits of data were altered during transmission of that data.

  • Oversize SDU PDU—Oversized service data unit (interface information that is unchanged from layer to layer) protocol data unit (packet).

  • Invalid length PDU—Invalid protocol data unit (packet) length.

  • PDU CRC32 errors—Protocol data unit for CRC errors.

  • Reassembly timer expired PDU—A PDU can span multiple ATM cells. If the remainder of the PDU does not arrive within a set time period, the reassembly timer expires, and the PDU is discarded.

Display Managed CID Counter Command

Use the dspmngcidcnt command to display the managed CID count for a specified endpoint. Example 22-14 shows the dspmngcidcnt output.

Example 22-14 dspmngcidcnt Output

smoke.1.3.VISM8.a > dspmngcidcnt 50

 EndptNum:      50
 Lcn:        131
 Cid:        9
 SentPkts:      76843
 RcvdPkts:      76844
 SentOctets:     3301527
 RcvdOctets:     3301570
 LostPkts:      0
 Jitter:       0
 Latency:      0
 Ext AIS Rcvd:    0
 Ext RAI Rcvd:    0
 Ext Conn AIS Rcvd: 0
 Ext Conn RDI Rcvd: 0

The dspmngcidcnt output includes the following information:

  • Sent packets—The number of packets sent to the network.

  • Received packets—The number of packets received from the network.

  • Sent octets—The number of octets sent to the network.

  • Received octets—The number of octets received from the network.

  • Lost packets—The number of packets lost during transmission.

  • Jitter—The phase shift of digital pulses over a transmission medium.

  • Latency—The time it takes to get information through a network; waiting time or time delay.

  • External AIS received—The number of alarm indicator signals received from the line.

  • External RAI received—The number of remote alarm indicators (RAIs) received from the line.

  • External connection AIS received—An external connection AIS has been received.

  • External connection RAI received—An external connection RAI has been received.

13. Introduction to Multiprotocol Label Switching | Next Section Previous Section

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