Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Packet Flow Issues

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This article describes how to troubleshoot packet flow issues for Cisco NX-OS.
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{| align="right" border="1"
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|align="center"|'''Guide Contents'''
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|[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Overview|Troubleshooting Overview ]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Installs, Upgrades, and Reboots|Troubleshooting Installs, Upgrades, and Reboots]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Licensing|Troubleshooting Licensing]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting VDCs|Troubleshooting VDCs]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting CFS|Troubleshooting CFS]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Ports|Troubleshooting Ports]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting vPCs|Troubleshooting vPCs]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting VLANs|Troubleshooting VLANs]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting STP|Troubleshooting STP]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Routing|Troubleshooting Routing]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Unicast Traffic|Troubleshooting Unicast Traffic]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting WCCP|Troubleshooting WCCP]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Memory|Troubleshooting Memory]]<br>''Troubleshooting Packet Flow Issues(this section)''<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting FCoE|Troubleshooting FCoE]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Before Contacting Technical Support|Before Contacting Technical Support]]<br>[[Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Troubleshooting Tools and Methodology|Troubleshooting Tools and Methodology]]
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==Packet Flow Issues==
==Packet Flow Issues==

Latest revision as of 22:14, 13 March 2013

This article describes how to troubleshoot packet flow issues for Cisco NX-OS.

Guide Contents
Troubleshooting Overview
Troubleshooting Installs, Upgrades, and Reboots
Troubleshooting Licensing
Troubleshooting VDCs
Troubleshooting CFS
Troubleshooting Ports
Troubleshooting vPCs
Troubleshooting VLANs
Troubleshooting STP
Troubleshooting Routing
Troubleshooting Unicast Traffic
Troubleshooting WCCP
Troubleshooting Memory
Troubleshooting Packet Flow Issues(this section)
Troubleshooting FCoE
Before Contacting Technical Support
Troubleshooting Tools and Methodology

Contents





Packet Flow Issues

Packets could be dropped for the following reasons :

  • Software switched packets could be received from the interface, but dropped by the supervisor because of rate limits.
  • Packets could be dropped because of a QoS policy.
  • Hardware switched packets could be dropped by the hardware because of a bandwidth limitation.


Packets Dropped Because of Rate Limits

Use the show hardware rate-limit command to determine if packets are being dropped because of a rate limit.

dctl-n7010-7# show hardware rate-limit copy 

Units for Config: packets per second
Allowed, Dropped & Total: aggregated since last clear counters

Rate Limiter Class                       Parameters
------------------------------------------------------------
copy                                     Config    : 30000          
                                         Allowed   : 13651778            
                                         Dropped   : 228295 <-- caused by ICMP redirect or OSPF Hello       
                                         Total     : 13880073
dctl-n7010-7(config)# show hardware rate-limit module 1 

Units for Config: packets per second
Allowed, Dropped & Total: aggregated since last clear counters

Rate Limiter Class                       Parameters
------------------------------------------------------------
layer-3 mtu                              Config    : 500            
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

layer-3 ttl                              Config    : 500            
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

layer-3 control                          Config    : 10000          
                                        Allowed   : 17020000            
                                        Dropped   : 88790262  <---HSRP, OSPF hello         
                                        Total     : 105810262           

layer-3 glean                            Config    : 100            
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

layer-3 multicast directly-connected     Config    : 3000           
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   
 
layer-3 multicast local-groups           Config    : 3000           
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

layer-3 multicast rpf-leak               Config    : 500            
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

layer-2 storm-control                    Config    : Disabled

access-list-log                          Config    : 100            
                                        Allowed   : 0                   
                                        Dropped   : 0                   
                                        Total     : 0                   

copy                                     Config    : 30000          
                                        Allowed   : 552173              
                                        Dropped   : 0                   
                                        Total     : 552173              

receive                                  Config    : 30000          
                                        Allowed   : 85134               
                                        Dropped   : 0                   
                                        Total     : 85134               

layer-2 port-security                    Config    : Disabled

Packets Dropped Because of a QoS Policy

Use the show policy-map interface control-plane command to determine if packets are being dropped because of a QoS policy.

dctl-n7010-7# sh policy-map interface control-plane 
   class-map copp-system-class-exception (match-any)
     match exception ip option
     match exception ip icmp unreachable
     police cir 360 kbps , bc 250 ms 
     module 1 :
       conformed 0 bytes; action: transmit 
       violated 0 bytes; action: drop 

     module 2 :
       conformed 0 bytes; action: transmit 
       violated 0 bytes; action: drop 

     module 3 :
       conformed 0 bytes; action: transmit 
       violated 0 bytes; action: drop 

     module 4 :
       conformed 0 bytes; action: transmit 
       violated 0 bytes; action: drop 

     module 10 :
       conformed 11614462878 bytes; action: transmit 
       violated 3097405384908 bytes; action: drop

Packets Dropped in Hardware

Use the following show hardware commands to determine if packets are being dropped by the hardware.

  • show hardware internal statistics rates
  • show hardware internal statistics pktflow all

show hardware internal statistics rates

dctl-n7k-dist-1# sh hardware internal statistics rates 
 + ============================= 
 + R2D2 Instance 0
 + ============================= 
 |
 |-- Ingress IN
 |   |--- Packets/sec
 |   |   |---    sum: 0
 |   |
 |   |--- Bytes/sec
 |   |   |---    sum: 0
 |
 |-- Ingress OUT
 |   |--- Packets/sec
 |   |   |---    sum: 0
 |   |
 |
 |-- Egress IN
 |   |--- Packets/sec
 |   |   |---    sum: 0
 |   |
 |
 |-- Egress OUT
 |   |--- Packets/sec
 |   |   |---    sum: 0
 |   |
 |   |--- Bytes/sec
 |   |   |---    sum: 0
 |
 |
 |
 + ============================= 
 + Metropolis Instance 0
 + ============================= 
 |
 |-- Ingress IN
 |   |--- Packets/sec
 |   |   |---     I1: 2
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |   |
 |
 |-- Ingress OUT
 |   |--- Packets/sec
 |   |   |---     I1: 2
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |   |
 |   |--- Bytes/sec
 |   |   |---     I1: 1166
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |
 |-- Egress IN
 |   |--- Packets/sec
 |   |   |---     I1: 0
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |   |
 |   |--- Bytes/sec
 |   |   |---     I1: 0
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |
 |-- Egress OUT
 |   |--- Packets/sec
 |   |   |---     I1: 0
 |   |   |---    sum: 0
 |   |
 |
 |
 |

show hardware internal statistics pktflow all

This command displays per ASIC statistics, including packets into and out of the ASIC. This command helps to identify where packet loss is occurring.

dctl-n7k-dist-1# show hardware internal statistics pktflow all
bhv_bitmask:0
|------------------------------------------------------------------------|
| Device:R2D2                     Role:MAC                               |
| Packets
|------------------------------------------------------------------------|
 Instance: 0                     Ports:-
|----------|-------------------|------------------|
|          |        IN         |       OUT        |
|----------|-------------------|------------------|
|Ingress   | 00000000014a40c0  | 00000000014a40c0 |
|----------|-------------------|------------------|
|Egress    | 000000000007e9dc  | 000000000007e9dc |
|----------|-------------------|------------------|

|------------------------------------------------------------------------|
| Device:Metropolis               Role:REWR                              |
| Packets
|------------------------------------------------------------------------|
 Instance: 0                     Ports:-
|----------|-------------------|------------------|
|          |        IN         |       OUT        |
|----------|-------------------|------------------|
|Ingress   | 00000000014a40c0  | 0000000001498ccc |
|----------|-------------------|------------------|
|Egress    | 000000000007e9dc  | 000000000007e9dc |
|----------|-------------------|------------------|

|------------------------------------------------------------------------|
| Device:Octopus                  Role:QUE                               |
| Packets
|------------------------------------------------------------------------|
 Instance: 0                     Ports:-
|----------|-------------------|------------------|
|          |        IN         |       OUT        |
|----------|-------------------|------------------|
|Ingress   | 0000000001498ccc  | 0000000001498cc6 |
|----------|-------------------|------------------|
|Egress    | 000000000007e9c5  | 000000000007e9dc |
|----------|-------------------|------------------|

 *** Counters above represent packets combined into a larger one ***

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