Owner's Manual

Chapter 20. IPv4 Unicast Routing | 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 [ <num_routes_needed> | maximum | default ]
slot [all | <slot_num>]
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