Chapter 18 Span; Information About Span; Span Session Guidelines - Cisco Nexus 1000V Troubleshooting Manual

SPAN
This chapter describes how to identify and resolve problems that relate to SPAN and includes the
following topics:
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Information About SPAN

The Switched Port Analyzer (SPAN) feature (sometimes called port mirroring or port monitoring)
selects network traffic for analysis by a network analyzer. The network analyzer can be a Cisco
SwitchProbe or other Remote Monitoring (RMON) probe.
The Cisco Nexus 1000V supports two types of SPAN:
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For detailed information about how to configure local SPAN or ERSPAN, see the Cisco Nexus 1000V
System Management Configuration Guide.

SPAN Session Guidelines

The following are SPAN session guidelines:
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OL-31593-01
Information About SPAN, page 18-1
Problems with SPAN, page 18-2
SPAN Troubleshooting Commands, page 18-3
SPAN (local SPAN) that can monitor sources within a host or VEM.
Encapsulated remote SPAN (ERSPAN) that can send monitored traffic to an IP destination.
When a SPAN session contains multiple transmit source ports, packets that these ports receive might
be replicated even though they are not transmitted on the ports. Examples include the following:
Traffic that results from flooding
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– Broadcast and multicast traffic
For VLAN SPAN sessions with both receive and transmit configured, two packets (one from receive
and one from transmit) are forwarded from the destination port if the packets get switched on the
same VLAN.
After VMotion, the following might occur:
A session is stopped if the source and destination ports are separated.
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A session resumes if the source and destination ports end up on the same host.
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C H A P T E R
Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
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