Information About MAC/ARP Hardware Resource Carving Template
On the Cisco Nexus device, the IPv4/IPv6 and unicast/multicast entries share the same tables. In addition, the same tables are shared by Station Table Management (STM) and the Host Route Table (HRT). STM is the part of the host table that holds the MAC entries. HRT is the part of the host table that holds ARP, IPv6 ND, and /32 host routes. The STM/HRT template profile feature is specific to the Cisco Nexus device. This feature provides you with a flexibility to carve STM & HRT table sizes per their requirements. The total table size is 256k. You can apply any of the following four pre-defined templates:
Template Profiles | Specifications |
---|---|
hrt-128-stm-128 |
HRT size: 128k, STM size: 128k (default size) |
hrt-96-stm-160 |
HRT size: 96k, STM size: 160k |
hrt-64-stm-192 |
HRT size: 64k, STM size: 192k |
hrt-32-stm-224 |
HRT size: 32k, STM size: 224k |
Note |
The hrt-96-stm-160 and hrt-32-stm-224 template profiles are not recommended in the presence of IPv6 entries. This is because these two profiles result in an odd number of SRAMs available for the HRT table. Insertion of IPv6 entries need free spaces in 2 consecutive SRAMs. The recommended maximum ARP percentage of the configured value is 50%. The recommended maximum MAC percentage of the configured value is 90%. For example, if the profile is set to hrt-96-stm-160, 50% of 96k (48k) is the recommended maximum ARP entries that a switch can have. |
When applying or unapplying a template profile, you need to enter the copy running-config startup-config command and reload the switch in order to activate the newly applied/default template. These commands are per-switch based, therefore they need to be configured explicitly on a vPC peer switch.