A9K-2x100GE NPU

[s.giunt]

A9K-2x100GE Line Card has 2 NPUs per port as shown in this picture:

But each NPU is unidirectional. Since each Ezchip Typhoon NPU supports 60Gbps (~45Mpps), how is it possible for a single port to support more than 60Gbps?

[M02@rt37]

Hello @s.giunt,

In a bidirectional context (full-duplex), a port's throughput is often measured separately for incoming and outgoing traffic. So, if a port is specified as supporting, for example, 100Gbps, it usually means it can handle 100Gbps in each direction, summing up to 200Gbps (100Gbps in and 100Gbps out).

The fact that each NPU is unidirectional doesn't necessarily limit the overall throughput of the port. The line card is designed to handle bidirectional traffic, and the NPUs collectively contribute to the overall capacity of the port.

[Joseph W. Doherty · Accepted solution]

It appears that NPU can handle 60 Gbps both in and out, but when dedicated to just a single direction in or out, you now have 120 Gbps capacity (providing the support for 100 Gbps in or out [also why they use a pair]).

This capacity, i.e. dual 200 Gbps ports, is also found here.  Look at second diagram, 2011, right bottom.