Cisco Cisco Nexus 5010 Switch Libro bianco

 

 

© 2014 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information. 

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Figure 1.    Latency Monitoring 

 

In Figure 1, when a packet enters the source port, it is marked with a time stamp (t0). When it exits the destination 

port, the time stamp is marked again (t1). The latency monitoring tool essentially provides the time (t1 - t0). 

Switch Latency Measurement Modes 

The following modes can be configured between ingress and egress port pairs: 

● 

Instantaneous mode: This is the mode enabled by default. No configuration is needed to see latency values 

in this mode. This mode is useful for getting a quick snapshot of port-pair latency. 

● 

Linear Histogram mode: This mode is useful for seeing the number of packets that had the user-configured 

latency value. 

● 

Exponential Histogram mode: This mode provides an exponential view of the linear histogram mode. 

● 

Custom Histogram mode: This mode displays the number of packets that are in the low-latency range and 

the number of packets that are in the high-latency range. 

In Instantaneous mode, the minimum, maximum, and average latency can be collected. This mode is enabled by 

default. No configuration is required. 

Following is a sample of latency measurement output in Instantaneous mode. Eth 1/1 is the egress port and 1/6 is 

the ingress port. 

-------------------------------------------------------------------------------- 

Egress Port: Ethernet1/1 Ingress Port: Ethernet1/6 Mode: Inst 

-------------------------------------------------------------------------------- 

|          |       Minimum       |       Maximum         |     Average         | 

-------------------------------------------------------------------------------- 

|  cnt  |                   890 |                      1020|           960     | 

--------------------------------------------------------------------------------