Cisco Cisco Nexus 9000v Switch Troubleshooting Guide
Contents
Introduction
Background Information
Terminology
ACL TCAM Regions
Defaults
Nexus 9500 Series TCAM Allocation
Nexus 9300 Series TCAM Allocation
Configuration
Example Scenario
Verification Commands
Errors and Solutions
Design Guidelines and Limitations
Related Information
Introduction
This document explains how Nexus 9000 ternary content-addressable memory (TCAM) carving
works. It cover the current and most common concepts, configuration, and error messages.
works. It cover the current and most common concepts, configuration, and error messages.
This document is not comprehensive - there are too many TCAM carving combinations to cover.
The purpose of this document is to help users understand how the TCAM allocation works so they
can come up with valid configurations that meet their needs.
The purpose of this document is to help users understand how the TCAM allocation works so they
can come up with valid configurations that meet their needs.
Background Information
If you want to use a non-default feature for Nexus 9000 Series switches, you must manually carve
out TCAM space for the features. By default all TCAM space is allocated.
out TCAM space for the features. By default all TCAM space is allocated.
Terminology
Feature Width - There are single-width and double-width features. A single-width feature
requires at minimum one slice. A double-width feature at minimum requires two slices. For
both single- and double-width features, the total size, if greater than 256, must be a multiple of
512. A slice can be allocated to one region only. For example, you cannot use a 512-size
slice in order to configure two features of size 256 each nor can you use a 512-size slice in
order to configure a single double-width feature.
requires at minimum one slice. A double-width feature at minimum requires two slices. For
both single- and double-width features, the total size, if greater than 256, must be a multiple of
512. A slice can be allocated to one region only. For example, you cannot use a 512-size
slice in order to configure two features of size 256 each nor can you use a 512-size slice in
order to configure a single double-width feature.
●
Slice - A unit of memory allocation. Slices can be of size 256 or of size 512, measured in
bytes.
bytes.
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TCAM - Ternary Content Addressable Memory. This is the space in hardware where access-
lists (ACLs) are stored. This is a specialized piece of memory that stores complex tabular
data and supports very rapid parallel lookups.
lists (ACLs) are stored. This is a specialized piece of memory that stores complex tabular
data and supports very rapid parallel lookups.
●
ACL TCAM Regions