VxBlock: Guidelines for TCAM Usage with Cisco Nexus Switch
Summary: This article explains guidelines for a TCAM usage issue.
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Instructions
Facts:
Information:
TCAM Usage issue:
Example: A customer wants to create MAC PACLs to support the HSRP isolation. When they attempt to assign TCAM space to the mac-ifacl region, they receive the below error:
Current Default TCAM utilization of customer:
Recommendation 1:
The mac-ifacl feature that is required is a double-sized block. This requires two slices of either 256 or 512 bytes.
From the current configuration, notice that we are not using IPv4 Port QoS [qos]. We can take that double size feature and assign it to mac-ifacl with two commands:
Recommendation 2:
Take the two 512 slices from RACL and assign that space to mac-ifacl. This gives us an available 256 slice so we can assign that available slice to any other single-width feature.
Recommendation 3:
Another possibility is to set SPAN to 0. This leaves us with two 256-bytes slices that we can allocate to the double-width feature mac-ifacl.
- Cisco Nexus 9000
- TCAM
Information:
TCAM Usage issue:
Example: A customer wants to create MAC PACLs to support the HSRP isolation. When they attempt to assign TCAM space to the mac-ifacl region, they receive the below error:
# hardware access-list tcam region mac-ifacl 256
ERROR: Aggregate TCAM region configuration exceeded the available Ingress TCAM slices. Please re-configure.
Current Default TCAM utilization of customer:
# sh sys int acce globals | egrep -i '[0-9]+ +[0-9]+ +[1-9][0-9]+|--' --------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------- IPV4 PACL [ifacl]( 1) 3 0 512 1 IPV4 Port QoS [qos]( 4) 6 3072 256 2 IPV4 VACL [vacl]( 13) 15 512 512 1 IPV4 RACL [racl]( 19) 21 1024 512 1 Ingress System( 37) 1 2048 256 2 SPAN [span]( 39) 2 3584 256 1 Ingress COPP [copp]( 40) 40 2560 256 2 Redirect [redirect]( 44) 46 1536 512 1 VPC Convergence/ES-Multi Home [vpc-convergence]( 54) 57 4096 256 1
Recommendation 1:
The mac-ifacl feature that is required is a double-sized block. This requires two slices of either 256 or 512 bytes.
From the current configuration, notice that we are not using IPv4 Port QoS [qos]. We can take that double size feature and assign it to mac-ifacl with two commands:
# hardware access-list tcam region qos 0 WARNING: On module 1, 4 entries are in use in the region IPV4 Port QoS [qos] on instance 0, but carving size is 0 [0*2]. Warning: Please save config and reload the system for the configuration to take effect
# hardware access-list tcam region mac-ifacl 256
Warning: Please save config and reload the system for the configuration to take effectAfter the reload:
9396-a# sh sys int acce globals | egrep -i '[0-9]+ +[0-9]+ +[1-9][0-9]+|--' IPV4 PACL [ifacl]( 1) 3 0 512 1 MAC PACL [mac-ifacl]( 3) 5 3072 256 2 IPV4 VACL [vacl]( 13) 15 512 512 1 IPV4 RACL [racl]( 19) 21 1024 512 1 Ingress System( 37) 1 2048 256 2 SPAN [span]( 39) 2 3584 256 1 Ingress COPP [copp]( 40) 40 2560 256 2 Redirect [redirect]( 44) 46 1536 512 1 VPC Convergence/ES-Multi Home [vpc-convergence]( 54) 57 4096 256
Both features are configured. Follow this template to achieve the goal.
Recommendation 2:
Take the two 512 slices from RACL and assign that space to mac-ifacl. This gives us an available 256 slice so we can assign that available slice to any other single-width feature.
Recommendation 3:
Another possibility is to set SPAN to 0. This leaves us with two 256-bytes slices that we can allocate to the double-width feature mac-ifacl.
Produse afectate
VxBlock and Vblock Systems, NetworkingProprietăți articol
Article Number: 000207091
Article Type: How To
Ultima modificare: 20 Nov 2025
Version: 2
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