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BL460 G1 with FlexFabric 10/24 - 2,5Gbit NIC ?

Trusted Contributor

BL460 G1 with FlexFabric 10/24 - 2,5Gbit NIC ?

Timo wanted to know if the NICson the BL460 G1 could operate at 2.5Gb/sec.

Ramu replied:




BL460G1 has 2* 1Gbps NIC ports embedded. It can function only at 1Gbps speed max.


I don't think it can work at 2.5Gbps speed even if connected to 10Gbps switch.


Others can correct me if I'm wrong.




David then joined in:




There is a 10Gb “pipe” that runs between the LOM ports or mezzanine ports on the server through the mid-plane to the interconnect bay for each connection.  That “pipe” is non-denominational (it is a digital signal that carries traffic regardless of it being Ethernet, Fibre Channel or Infiniband) and that pipe is made up of 4 “lanes” of high-speed serial traffic, serialized at one end and de-serialized at the other (referred to as “SerDes”).  10Gb takes all 4 lanes and 1Gb only takes one.  Since it doesn’t really become “Ethernet” for example until the signal hits a transceiver (e.g. on a Pass-Through Module), standard Ethernet speeds don’t really apply.  With a 10Gb switch or VC interconnect, all the interconnect knows is that 1 lane is being used and so it can take up to the 2.5Gb the lane is capable of.




Any other comments or suggestions?

Trusted Contributor

Re: BL460 G1 with FlexFabric 10/24 - 2,5Gbit NIC ?

Charles joined in:




There seems to be a bit of confusion in this email chain, so hopefully I can clear it up


1)             Our original 10GbE product was based on CX4 signaling, which uses 4 x 2.5gb lanes.  That was a double wide switch. Our current 10GbE products use KR signaling, which uses 1 x 10Gb lane.

2)             The 2.5Gb function is a Broadcom specific feature that is supported only when you have Broadcom products at both ends of the link.  It uses a 1 x 2.5Gb lane.