I get confused with speed of adaptors having multiple ports. E.g. chelsio T-520CR is 10Gbits dual port adaptor. Does this means both ports have 10Gbits speed i.e. effective 20Gbits or total speed would be 10Gbits regardless number of ports?

As per my knowledge effective speed is 10Gbits, its just 2 ports allows us 2 interfaces of 10Gbits card. Please correct me if I am wrong.


  • 2
    "Dual Port" means it's functionally two NICs. The OS will see two independant network interfaces. Each port operating at 10G -- and possibly lower speeds. – Ricky Jan 7 '20 at 14:43
  • Yeh my thoughts too, so this is like 2 10Gbps interfaces. Thanks this clears my confusion. – Vinit Agnihotri Jan 8 '20 at 12:10
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Dec 17 '20 at 14:40

The effective speed, in theory, might be 20Gbps depending on how you set up your network adapter.

From the very get-go, the important thing is that the two ports of Chelsio T-520CR support link aggregation & fail-over features which are ideal for critical network applications that require redundancy, high-availability, and high throughput capabilities.

With 2 ports, you can use "link aggregation" or "bonding" which makes the 2 ports look just like 1 regular port to the applications you are running. There are pros and cons to this:


  1. Better theoretical speed (though you will be limited by the slowest part of your connection path)
  2. Better fault tolerance - this was the original intent of the technology
  3. Allows load balancing between 2 networks (E.g. cable + DSL)


  1. Your speed is still limited by the slower connection path. For instance, if your internet service provider is only giving you 10Gbps, you can't connect to the internet any faster than that by using 2 ports
  • Creating a bond on an end-host puts the adapter in promiscuous mode? Can you clarify that? – cpt_fink Jan 8 '20 at 4:16
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    Promiscuous mode is optional actually. It's not really needed unless running network monitoring tools like tcpdump. It is quite common to enable promiscuous mode on NICs so that all traffic is seen (instead of seeing only traffic destined for the localhost). I'll remove that as a con. – Bobby Voychin Jan 8 '20 at 12:05
  • Thank you, this helps resolving my confusion. – Vinit Agnihotri Jan 8 '20 at 12:12
  • I'm glad I've been helpful. Would you mind accepting the answer so that the question doesn't keep resurfacing? – Bobby Voychin Jan 8 '20 at 14:36
  • Apologies, this is my first question, and I do not know how to accept this answer and close thread. Can you please let me know how to achieve this? Thanks – Vinit Agnihotri Jan 9 '20 at 6:35

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