Managing IPv6 Routes and Hosts in External Tables

When external LPM tables are supported and configured on a switch, the configuration setting applies only to the external LPM tables. You can configure the external LPM to contain both IPv4 and, or, IPv6 routes. Internal LPM tables only store IPv4 routes.

The configure forwarding external-tables command using the ipv6 and ipv4-and-ipv6 variables supports larger IPv6 route and host scaling in external LPM tables.

When an external LPM table is configured for l3-only ipv6, no IPv6 routes or IPv6 hosts are configured in any of the internal hardware tables. This provides the highest IPv6 scale, and avoids contention with IP Multicast in the L3 Hash hardware table.

IPv6 hardware and slowpath forwarding are supported on user-created Virtual Routers, and IPv6 tunnels are only supported on VR-Default.

The size of the internal LPM tables, and the size of the L3 Hash and Next Hop tables are fixed. For specific information on hardware capacity, refer to the following table, the following table, and the following table in IPv4 Unicast Routing.


If you require a large number of IPv6 routes, you should use only xl-series modules, or a Summit X480 standalone, or a SummitStack comprised only of the X480. SummitStacks, or a BD8800 containing a mix of high- and low-capability hardware (slots without External TCAM) does not support more than 100,000 IPv6 routes present.