Netgear XCM8810 Chassis User Manual - Page 609

NETGEAR 8800 User Manual Note: Gateway entries are entries that represent routers or tunnel endpoints used to reach remote hosts. Gateway entries are not aged and are not replaced by IPv6 hosts or multicast entries in the L3 Hash table or by any entries requiring space in the Next Hop table. The software can move gateway entries from the LPM table to the L3 Hash table to make room for new reserved routes. Calculating the Number of Routes Needed Guidelines for calculating the number of routes to reserve are provided in the NETGEAR 8800 Chassis Switch CLI Manual description for the following command: configure iproute reserved-entries [ | maximum | default ] slot [all | ] Lower-Capacity Hardware NETGEAR 8800 modules are considered lower-capacity hardware. The XCM8800 software supports the coexistence of higher- and lower-capacity hardware in the same NETGEAR 8800 chassis. To allow for coexistence and increased hardware forwarding, when the number of IPv4 routes exceeds 25,000, the lower-capacity hardware automatically transitions from using LPM routing to forwarding of individual remote hosts, also known as IP Forwarding Database (IP FDB) mode. Lower capacity hardware operating in IP FDB mode is indicated with a d flag in the output of show iproute reserved-entries statistics command, indicating that only direct routes are installed. ECMP Hardware Table IP route sharing and the ECMP hardware table are introduced in IP Route Sharing and ECMP on page 598. The following sections provide guidelines for managing the ECMP hardware table: • ECMP Table Configuration Guidelines on page 609 • Troubleshooting: ECMP Table-Full Messages on page 611 ECMP Table Configuration Guidelines The ECMP table contains gateway lists, and each gateway list defines the equal-cost gateways that lead to a destination subnet. When IP route sharing is enabled, subnet entries in the LPM table can be mapped to gateway list entries in the ECMP table, instead of to a single gateway within the LPM table. This mapping is managed in one of two ways, depending on the platform. For the NETGEAR 8800, each LPM table entry mapping requires a unique entry in the ECMP table. The gateway sets for the platforms listed above might be unique or might be the same as that used for another LPM table entry. Subnet entries in the LPM table cannot map to the same Chapter 20. IPv4 Unicast Routing | 609