Problems With Span - Cisco Nexus 1000V Troubleshooting Manual

Problems with SPAN

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Problems with SPAN
The following are symptoms, possible causes, and solutions for problems with SPAN.
Symptom
You observe issues with VM
traffic after configuring a
session with Ethernet
destinations.
A session state is up and the
packets are not received at
the destination ports.
The session displays an error. —
The ERSPAN session is up,
but does not see packets at
the destination.
Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
18-2
The following are required for a running SPAN session:
The limit of 64 SPAN sessions is not exceeded.
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At least one operational source is configured.
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At least one operational destination is configured.
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The configured source and destination are on the same host.
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The session is enabled with the no shut command.
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A session is stopped if any of the following occurs:
All the source ports go down or are removed.
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All the destination ports go down or are removed.
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All the source and destination ports are separated by VMotion.
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The session is disabled by a shut command.
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Possible Causes
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The ERSPAN ID is not
configured.
An ERSPAN-enabled
VMKernel NIC is not
configured on the host or
VEM.
The ERSPAN-enabled
VMKernel NIC is not
configured with a proper IP,
gateway, or both.
Solution
Ensure that the Ethernet destination is not connected to the
same uplink switch. The SPAN packets might cause problems
with the IP tables, the MAC tables, or both on the uplink
switch, which can cause problems with the regular traffic.
Verify that the correct VLANs are allowed on the trunk
destination ports.
1. Make sure that VSM-VEM connectivity is working
correctly.
2. Force reprogramming of the session on the VEM.
shut
no shut
Make sure that the ERSPAN ID is configured at the
destination.
Make sure that you create a VMKernel NIC on the host using
a port profile configured for ERSPAN.
Ping the ERSPAN IP destination from the host VMKernel
NIC.
vmkping dest-id
Use the vempkt command to capture packets on the
VMKernel NIC LTL and ensure ERSPAN packets are being
sent. Use the vemlog debug sfspan d command so that the
ERSPAN packets appear in the vempkt capture log.
Chapter 18 SPAN
OL-31593-01