This document describes how to troubleshoot permanent virtual circuit (PVC) problems in a Cisco IGX 8400 or BPX 8600 series switch running 9.1 Switch Software or later.
There are no specific requirements for this document.
The information in this document is based on this software and hardware:
Switch Software 9.1 and later
IGX 8400 Universal Switching Module (UXM)
BPX 8600 Broadband Switch Module (BXM)
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
For more information on document conventions, refer to the Cisco Technical Tips Conventions.
UXM and BXM modules support ATM Forum compliant traffic between user and network equipment and within Cisco networks. Both modules display statistics for connections whether they are operating in line mode or trunk mode. Based on this functionality, the UXM and BXM can display statistics at each point in a connection path.
Connections are referred to as channels for statistics collection using the dspchstats command. Channel statistics provide information to help troubleshoot network connectivity problems such as excessive delay or one-way traffic on customer premise equipment (CPE). Connections that traverse an IGX or BPX are known as via connections. The diagram below provides an oversimplified example of the terminating and via segments of a connection traversing BPX BXMs.
The dspchstats command identifies discards on a connection and requires the connection number or trunk identifier to display useful information. The dspchstats command syntax depends upon the connection type as described here:
|terminating||dspchstats module_slot.line.vpi.vci , where vpi = virtual path identifier; vci = virtual channel identifier.|
|via||dspchstats module_slot.trunk.lcn , where lcn = logical channel number.|
This section assumes that the dspchstats module_slot.line.vpi.vci command does not display discards or congestion at either terminating segment. It also assumes that end-to-end connectivity is slow or successful in only one direction. The connection could be experiencing discards or a stuck-module queue at the via segments.
Complete these steps to isolate the source of the problem:
Identify all connections via segment logical channel numbers.
The service-level dcct slot.port.vpi.vci command contains multiple screens of information about a specific connection, including six screens for local connections and seven screens for connections routed across a network. The command output depends upon the switch type. The table below provides the equivalent fields for the IGX 8400 and BPX 8600 series switches.
IGX 8400 BPX 8600 Master Lcon Index Mstr LCon Idx Master Node Number Master Node# Slot.port Trunk LCN This Chan
Use the dcct slot.port.vpi.vci command and record the following information to evaluate the via segments of the ATM connection used in this example:
Logical connection (LCON) number . The LCON is unique per node. A connection only has one pair of LCONs representing the master and slave ends.
Master Node Number. Indicated by a 1 in the Master field on the first screen or in the Master Node Number field on the last screen of the dcct slot.port.vpi.vci command. A connection only has one master end representing the node on which the connection was built.
Trunk information (slot.port). The trunk information is specific to each end of the trunk.
Logical channel number (LCN). The logical number assigned to the connection on the card. A connection has one LCN per card and two LCNs per trunk.
g4static TN StrataCom IGX 8420 9.2.23 May 18 2000 1131 GMT Slot 11 Port 1 VPI.VCI 100.1 LCON# 16 &31875AC4 VC# 16 &3193FA88 Alloc 1 Bundled 0 MS Cmax,SM 10,10 mir 384000,384000 Exists 1 Never rtd 0 COS 0 peak 768000,768000 Master 1 No DC fnd 0 Hops 2 Cmax 200,200 Local 0 Failed 0 Src dc 10 %Utl 100,100 Pref only 0 Down,pend 0,0 Snk dc 10 FSTsts 1 No rt fnd 0 Cur route PREF Frst Pt,oe 3,3 Route wait 329493477 Path fail 0 BW needed No Bndl Sz,OE 0,0 Cdt reason None Derouted 0 baddr type 1 Group num 0 MS PLU,SM 2400,2400 RrtReq L,G 0,0 acc dev vx 0 VC count 1 MS CLU,SM 1000,1000 Route CDT 0 Max cost 100 VC index 16 Line rstr NONE RR Group # 10 Path 63/5 66/4 64 Prev LCON 17 Pref 63/5 66/4 64 Next LCON 65535 Slot 11 Port 1 VPI.VCI 100.1LCON# 16 &31875AC4 VC# 16 &3193FA88 !--- Five screens were skipped because they are not used in this document. XLAT DB Ptr 30D2FC5C XLAT Entry Ptr 30D0064C Slot.port.index 11.5.2 Sequence Number 6 State USED LTrk/OE LTrk 6 / 255 LCN/OE LCN 262 / 0 xmt/rcv baddr 1 / 2 (Note add 0x1000 for CBA) VPC 0 Conid 4102 Master Node Number 64 Master Lcon Index 16 Vc Index 16 Last Command dcct 220.127.116.11
Use the dspnds +n command to translate from node number to node name.
g4static TN Service IGX 8420 9.2.31 Aug. 28 2000 13:48 GMT NodeName J/ Num g5static /63 g4static /64 b4static /66 Last Command: dspnds +n
Important information from the dcct command is highlighted in bold. The Master Node Number and the Master Lcon Index number are required to identify relevant LCNs on a via node. The LCON of a connection on the master node is the Master Lcon Index for the connection through the network. Each connection has many LCNs, including ones for each card it travels through, but only one master LCON.
The last screen of the dcct slot.port.vpi.vci command for the BPX 8600 platform presents different information:
b4static VT StrataCom BPX 8620 9.2.23 May 18 2000 1145 GMT Slot 5 Port 0 VPI 0 VCI 99 LCON# 23 &31CD2CC2VC# 23 &3216D6DE Base XLT ptr 31133648 Xlat ptr 310C792C Cur,Nxt Indx 2, 0 SEQ Number 10 State USED Trunk 7(5.3.255) !--- in the BPX, this is the Slot.port. OE Trunk 255(5.3.255) Out Trk Chan 0 This Chan 273 !--- in the BPX, this is the LCN. VPC(N) Conid 4351 Master Node# 66 Mstr LCon Idx 23 Last Command dcct 18.104.22.168
Use the dspchstats slot.port.lcn command to view the connection status of an IGX 8400 trunk using the information collected from the dcct command.
g4static TN StrataCom IGX 8420 9.2.23 May 18 2000 1135 GMT Trunk Channel Statistics 11.5 Lcn 262 Collection Time 0 day(s) 000013 Clrd 05/18/00 113533 Type Count Traffic Rate (cps) Cells Received from Port 1 From port 0 Cells Transmitted to Network 2 To network 0 Cells Received from Network 2 From network 0 Cells Transmitted to Port 2 To port 0 EOF Cells Received from Port 0 Cells Received with CLP=1 0 Cells Received with CLP=0 1 Non-Compliant Cells Received 0 Average Rx VCq Depth in Cells 0 Average Tx Vcq Depth in Cells 0 Ingress Vsvd Allowed Cell Rate 0 Egress Vsvd Allowed Cell Rate 0 Cells Rx with CLP=0 from Network 2 Cells Rx with CLP=1 from Network 0 Cells TX with CLP=0 to Port 2 Cells TX with CLP=1 to Port 0 Non-Comp Cells Rx w/CLP=0 dropped 0 Non-Comp Cells Rx w/CLP=1 dropped 0 Overflow Cells Rx w/CLP=0 dropped 0 Overflow Cells Rx w/CLP=1 dropped 0 OAM state (0OK,1FERF,2AIS) 0 Good Pdu's Received by the Sar 0 Good Pdu's Transmitted by the Sar 0 Rx pdu's discarded by the Sar 0 TX pdu's discarded by the Sar 0 Invalid CRC32 pdu rx by the sar 0 Invalid Length pdu rx by the sar 0 Shrt-Lgth Fail detected by the sar 0 Lng-Lgth Fail detected by the sar 0 This Command dspchstats 11.5.262 1 !--- The 1 is for a one-second screen refresh rate.
Use the dspchstats command to view the connection status of a BPX 8600 trunk using the information collected from the dcct command.
b4static VT StrataCom BPX 8620 9.2.23 May 18 2000 1146 GMT Trk Channel Statistics for 5.3.273 Cleared May 18 2000 1146 (\) PCR 0/0 cps Collection Time 0 day(s) 000017 Corrupted NO Traffic Cells CLP Avg CPS %util Chan Stat Addr 30F69634 From Port 0 0 0 0 To Network 0 --- 0 0 From Network 0 0 0 0 To Port 0 0 0 0 Rx Frames Rcv 0 NonCmplnt Dscd 0 Rx Q Depth 0 TX Q Depth 0 Rx CLP0 0 Rx Nw CLP0 0 Igr VSVD ACR 0 Egr VSVD ACR 0 TX Clp0 Port 0 Rx Clp0+1 Port 0 NCmp CLP0 Dscd 0 NCmp CLP1 Dscd 0 Oflw CLP0 Dscd 0 Oflw CLP1 Dscd 0 This Command dspchstats 5.3.273 1 !--- The 1 is for a one-second screen refresh rate.
This section shows an example of a via node discarding traffic.
Use the dspcon slot.port.vpi.vci command at the master end to determine the connection route through the network and examine the PVC segment at a via node. Then use these commands:
vt node_name — To connect to the next node in the connection path.
dnvc master_node_name master_Lcon_number — To collect the LCN information for each trunk card the connection traverses on the via node. The dnvc command is a service-level command whose output depends upon which switch type is used.
network2 VT StrataCom IGX 8420 9.1.16 Dec. 13 1999 0135 G+01 NW Lcon Ptr=317EA384, Vc Offset=0, MS Indx=175, SM Indx=177, GW=1 TRUNK XLAT INFO (MS) 4 (15.1) TRUNK XLAT INFO (SM) 2 (6.1) XLAT dB ptr 30ACF070 XLAT dB ptr 30ACF170 XLAT ptr 30AB4518 XLAT ptr 30ACC188 Cur Indx(d) 175 Cur Indx(d) 177 Nxt Indx(d) 0 Nxt Indx(d) 0 SEQ Number(d) 41 SEQ Number(d) 41 State, U State, U RCV,XMT dc(H) 10,10 RCV,XMT dc(H) 10,10 RCV,XMT ch(H) 12,11 RCV,XMT ch(H) 11,12 LCN(d) 175 LCN(d) 177 Master Node# 220 Master Node# 220 Mstr LCon Indx 1 Mstr LCon Indx 1 Mstr VC Indx 1 Mstr VC Indx 1 Last Command: dnvc network1 1
Use the dspchstats command to view the IGX connection status on a trunk using the information collected from the dnvc command.
network2 VT StrataCom IGX 8430 9.1.16 Dec. 14 1999 2340 GMT Trunk Channel Statistics 15.1 Lcn 175 Collection Time 0 day(s) 000037 Clrd 12/14/99 233956 Type Count Traffic Rate (cps) Cells Received from Port 40 From port 1 Cells Transmitted to Network 0 To network 0 Cells Received from Network 16 From network 0 Cells Transmitted to Port 16 To port 0 EOF Cells Received from Port 0 Cells Received with CLP=1 0 Cells Received with CLP=0 40 Non-Compliant Cells Received 0 Average Rx VCq Depth in Cells 4093 Average TX Vcq Depth in Cells 3 Cells Transmitted with EFCI=1 0 Cells Transmitted with EFCI=0 16 This Command: dspchstats 15.1.175
In this example, the dspchstats command isolated the problem to IGX 8400 switch network2 trunk 15.1. In this example, a UXM defect caused the transmit queue to fill and not play out cells. After the UXM transmit queue filled, subsequent traffic was discarded.
Avoid using disruptive commands such as the resetcd slot_number h command, unless all network traffic has been routed from the offending trunk. Use the cnfpref connection_number command to restore data service by routing the connection around the offending trunk.
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.