Vendors can exaggerate the switching capacity of their products in many ways.
It can easily be overstated by summing various inputs and outputs. Some vendors, especially those selling Gigabit Ethernet and Layer 3 switches, double the stated throughput of their switches by counting packets once on the way in and once on the way out. For example, this makes a 25 Gbps switch look like a 50 Gbps switch. Using this technique, the throughput of the ASX-4000 would be calculated as 80 Gbps. Another questionable approach, often used by vendors of service provider and enterprise WAN switches, is to multiply the total number of ports by the individual port capacity.