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.
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 ***
