Intel Pro 1000 NIC throughput issue



  • Hello everyone,

    I am having issues with 2 Dual Port NICs in my Setup. The cards are being recognized by dmesg as "Intel(R) PRO/1000 Legacy Network Connection 1.1.0". Also I have an onboard NIC which is recognized as "Intel(R) PRO/1000 Network Connection 7.6.1-k"

    I am using Link Aggregation with VLANs, at least that was my original setup. However, I noted that when using the Dual Port NICs, my throughput according to iperf drops to 200Mbit/s, when only using the onboard NIC I have 900 Mbit/s (Link Aggregation still enabled, just one Cable connected). I've also tried only using a single port on one of the external cards, still the same issue. It seems like the pci cards are unable to go faster than 200MBit/s. The cards are long 64 Bit Cards, I have them in a 32 Bit Slot in use with an Intel Core 2 Duo processor.

    Is this normal? Would using a PCI-Express NIC fix the issue? I thought the Pro 1000 cards are the recommended Hardware, and what does Legacy mean in the dmesg output, are the cards "too old"/no longer supported? Is there something to tune to increase performance?



  • legacy pci slots are half duplex and bandwidth limited for gigabit traffic. you should be able to get more than 200Mbit, but there may be some limitations in the pci bridge. at any rate, pcie is a much better option.



  • @VAMike:

    legacy pci slots are half duplex and bandwidth limited for gigabit traffic. you should be able to get more than 200Mbit, but there may be some limitations in the pci bridge. at any rate, pcie is a much better option.

    Looks like we're seeing this PCI limitation more and more often ;-) Maybe we should put this in the Wiki.



  • @johnkeates:

    @VAMike:

    legacy pci slots are half duplex and bandwidth limited for gigabit traffic. you should be able to get more than 200Mbit, but there may be some limitations in the pci bridge. at any rate, pcie is a much better option.

    Looks like we're seeing this PCI limitation more and more often ;-) Maybe we should put this in the Wiki.

    Definitely for dual port cards, they really needed the PCI-X extensions (higher clock speed + 64 bits), which have been functionally obsolete for over a decade and aren't found on any current mobos AFAIK. (If there's a PCI slot at all, it's probably a bridge to PCIe, possibly shared with some other legacy stuff, and not really intended for high-bandwidth applications–it's just there for people who have some old serial port or firewire card or somesuch they don't want to get rid of or pay to replace with a new PCIe version.)


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