Hardware Forwarding Limitations

All switches can use hardware forwarding when the route mask is 64 bits or less. If the route mask is greater that 64 bits, limitations apply based on the hardware platform.

This support was added in ExtremeXOS Release 12.4 by using some of the slices previously used for ACL support to create a Greater Than 64 Bit (GT64B) table. The GT64B table stores only those routes with a mask greater than 64 bits. When IPv6 forwarding is enabled, the switch behavior is as follows:

All switches support hardware forwarding routes with masks greater than 64 bits. For number of routes supported, see the limits for the particular switch in the ExtremeXOS Release Notes.

Starting with ExtremeXOS 22.5, the ipv6-mask-length option provides greater hardware route scale and IP route sharing (ECMP) support for IPv6 “long-mask routes”, meaning IPv6 subnets with mask lengths 65–128 bits. This provides additional scale and resilience for IPv6 host routes whose mask length is 128 bits. Increasing scale and providing ECMP for IPv6 mask 65–128 routes decreases IPv4 route scale. The default IPv6 mask length is 64.

The configure forwarding internal-tables [ l2-and-l3 | more [l2 | l3-and-ipmc | routes {ipv6-mask-length [64 | 128]}]] command provides the ability to support additional L2 and L3 hosts, routes, or multicast table entries.

This support was added in ExtremeXOS Release 12.4 by using a hardware table designed for this purpose. When IPv6 forwarding is enabled, the switch behavior is as follows: