Quad or Dual NICs in new build?



  • I am a bit of a noob when it comes to networking and I was wondering if there was any use to having a quad NIC.

    I currently run pfSense with dual NICs with 1 port for WAN and another for LAN and an unmanaged switch

    If I use quad port like below:
    WAN Port DHCP
    LAN Port 1 - 192.168.2.0/24 - 16 port switch - WLAN (APs and WLAN devices)
    LAN Port 2 - 192.168.3.0/24 - 16 port switch - LAN (laptops, PCs, printers)
    LAN Port 3 - 192.168.4.0/24 - 16 port switch - multimedia devices (TV, play console)

    Will my LAN devices be able to communicate with the WLAN devices and vice-a-versa? And if yes, what other advantages are there over using a switch?

    i340-t2 is available for about $20 whereas 340-t4 is about $35-$40. I was wondering if spending almost twice would give me anything extra

    I also checked i350-tX prices but since i340 and i350 are basically the same except for a bit of power consumption, I guess sticking to i340 and saving some money is better.

    Thank you,





  • @SammyWoo:

    https://forum.pfsense.org/index.php?topic=145521.0

    Thanks but I had already read that thread. But I still fail to understand why some people put quad NICs in their router then instead of using VLANs?

    The only thing I gathered was in case you have 2 Internet providers then you can have 2 WANs, but other than that I don't understand how more than 2 NICs would be useful.

    I might just end up buying a dual NIC and set it up like I have it now, but I thought since I am building a new box, I'd rather understand the need for quad and invest in it in case it is useful. I don't see myself getting 2 ISPs as my area is only served by Comcast and no one else.

    What exactly is the use of having more than 2 NICs then? (apart from the 2 WAN scenario)


  • Netgate Administrator

    If you have a managed switch and VLANs in place already then you may not need more than 2 NICs. Or even just use 1 NIC!

    If you do not have a managed switch then using more interfaces for additional separated subnets might be easier/cheaper.

    Each Gigabit interface has a maximum throughput of 1000Mbps (more like 941in fact) in and out. Let's say, for example, you're using 2 VLANs on the same interface and transferring a large file between them.  Traffic goes into the NIC on one VLAN and back out on the other using all the available bandwidth on the NIC. And in fact you will get a slightly slower transfer since the receiving end has to send back some data to acknowledge receipt and that eats the data available for sending. You then have zero bandwidth available in either direction for other clients trying to use the internet or any other resource.
    If you have 4 NICs you can be transferring a file at wirespeed between two of them and still use the internet on the other unaffected. Providing the CPU is sufficiently powerful of course.

    Steve



  • @stephenw10:

    If you have a managed switch and VLANs in place already then you may not need more than 2 NICs. Or even just use 1 NIC!

    If you do not have a managed switch then using more interfaces for additional separated subnets might be easier/cheaper.

    Each Gigabit interface has a maximum throughput of 1000Mbps (more like 941in fact) in and out. Let's say, for example, you're using 2 VLANs on the same interface and transferring a large file between them.  Traffic goes into the NIC on one VLAN and back out on the other using all the available bandwidth on the NIC. And in fact you will get a slightly slower transfer since the receiving end has to send back some data to acknowledge receipt and that eats the data available for sending. You then have zero bandwidth available in either direction for other clients trying to use the internet or any other resource.
    If you have 4 NICs you can be transferring a file at wirespeed between two of them and still use the internet on the other unaffected. Providing the CPU is sufficiently powerful of course.

    Steve

    Thanks Steve. That's a great explanation. Is a J3355 sufficiently powerful to do that?


  • Netgate Administrator

    I've never actually used one but I believe it will pass >1Gbps so, yes. Someone else can probably post better numbers on that.

    Steve