Zoning Best Practice; Tcam Regions - Cisco MDS 9000 Series Configuration Manual

Configuring and Managing Zones
system default zone gs read-write
system default zone smart-zone disabled
See the
command output.

Zoning Best Practice

A Cisco Multilayer Director Switch (MDS) uses a special kind of memory called Ternary Content Addressable
Memory (TCAM) on its Fibre Channel (FC) linecards. This special memory provides an Access Control List
(ACL) type of function for Cisco MDS. The process that controls this functionality is called the ACLTCAM.
The E/TE ports (Inter Switch Links - ISLs) and F (Fabric) ports have their own programming, which is unique
to their respective port types.

TCAM Regions

TCAM is divided into several regions of various sizes. The main regions and the type of programming contained
in each region are described in
Table 11: TCAM Regions
Region
Region 1 - TOP SYS
Region 2 - SECURITY
Region 3 - Zoning
Region 4 - Bottom
2
TCAM regions are automatically configured and cannot be changed. TCAM is allocated on a per-module and
per-forwarding engine (fwd-eng) basis.
TCAM space on MDS 9148S and MDS 9250i fabric switches is significantly less than that on the director-class
Fibre Channel modules and newer fabric switches such as MDS 9396S, MDS 9132T, and the switches that
will be launched in the future.
When a port comes online, some amount of basic programming is needed on that port. This programming
differs according to the port type. This basic programming is minimal and does not consume many TCAM
entries. Typically, programming is performed on inputs such that frames entering the switch are subject to
this programming and frames egressing the switch are not.
ACL TCAM Alerting
Starting from Cisco MDS NX-OS Release 8.3(1), ACL TCAM usage alerting syslog messages were introduced
on all Cisco MDS switches except on Cisco MDS 9148S and MDS 9250i switches. From Cisco MDS NX-OS
Release 8.3(2), ACL TCAM usage alerting syslog messages were introduced on Cisco MDS 9148S and MDS
9250i switches.
Cisco MDS 9000 Series Command Reference
Table 11: TCAM Regions , on page
Programming Type
Fabric-Login, Port-Login, Diagnostics features (10%-20%)
Security, Interop-Mode-4 features, IVR ELS capture (5%-10%)
Zoning features, including IVR and SAN Analytics (50%-75%)
2
PLOGI,ACC, and FCSP trap, ISL, ECHO-permit (10%-20%)
When a hard-zoning failure occurs, Region 4 (bottom region) is used to program wildcard entries to
allow any-to-any communication.
for the description of the information displayed in the
137:
Cisco MDS 9000 Series Fabric Configuration Guide, Release 8.x
Zoning Best Practice
137