Guidelines And Limitations For Span And Erspan Sampling; Span And Erspan Truncation; Guidelines And Limitations For Span And Erspan Truncation; Creating Or Deleting A Span Session - Cisco Nexus 3548 series Configuration Manual

Configuring SPAN
source packets will be spanned. Similarly, if you configure the range as 1023, 1 out of every 1023 packets
will be spanned. This method provides an accurate count of SPAN or ERSPAN source packets, but it does
not include any time-related information about the spanned packets.
By default, SPAN and ERSPAN sampling are disabled. To use sampling, you must enable it for each SPAN
or ERSPAN session.

Guidelines and Limitations for SPAN and ERSPAN Sampling

SPAN and ERSPAN sampling have the following guidelines and limitations:
• Sampling is only supported for local and ERSPAN-src sessions.
• Sampling is not supported for ERSPAN-dst sessions.
• Sampling is not supported for Warp SPAN sessions.
• The supported sampling range is from 2 to 1023.

SPAN and ERSPAN Truncation

Cisco NX-OS Release 6.0(2)A4(1) introduces truncation of source packets for each SPAN or ERSPAN session
based on the size of their MTU. Truncation helps reduce SPAN or ERSPAN bandwidth by reducing the size
of packets monitored. MTU truncation can be set from 64 bytes to 1518 bytes. Any SPAN or ERSPAN packet
that is larger than the configured MTU size is truncated to the given size with a 4-byte offset. For example,
if you configure the MTU as 300 bytes, the maximum size of the replicated packet is 304 bytes.
By default, SPAN and ERSPAN truncation are disabled. To use truncation, you must enable it for each SPAN
or ERSPAN session.

Guidelines and Limitations for SPAN and ERSPAN Truncation

SPAN and ERSPAN truncation have the following guidelines and limitations:
• Truncation is only supported for local and ERSPAN-src sessions.
• Truncation is not supported for ERSPAN-dst sessions.
• Truncation is not supported for Warp SPAN sessions.
• The supported MTU range is from 64 bytes to 1518 bytes.

Creating or Deleting a SPAN Session

You create a SPAN session by assigning a session number using the monitor session command. If the session
already exists, any additional configuration information is added to the existing session.
Cisco Nexus 3548 Switch NX-OS System Management Configuration Guide, Release 7.x
Guidelines and Limitations for SPAN and ERSPAN Sampling
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