I got quite a bit of replies from sellers selling me cuSFP, insisting they work. So I'd like to clear up on this. For 10/100 to work on SFP slot, the PHY in the host needs to be multirate. Exception is SGMII which supposedly supports magic mode where SFP can ask it to send same bit 10 times, then SFP can discard 9/10 bits, to remain very dumb yet deliver 100M client on 1GE host. RGMII does not support this trick and this trick does not bring you down to 10M. One box that we have right now, which can't do any of this is ME-4924. There is absolutely no reason that you couldn't deliver 'media converter' or '2 port switch' in a SFP casing, to get that 1 10/100 port in every 4500-X or EX4550 port you need to cater some legacy. If my desire is odd (2 people have expressed off list they want same) this won't be built. But if this is somewhat common demand and missing product, we can certainly get such SFP built. Obviously this SFP would cost bit more than normal cuSFP, as it needs to do rudimentary buffering, packet dropping and it needs to have frame parser. On 29 August 2013 23:38, joel jaeggli <joelja@bogus.com> wrote:
On 8/29/13 6:08 AM, Saku Ytti wrote:
How do people deal with situation where you need <=48 SFP/SFP+ ports, but you occasionally need one or two cu 10/100 ports? arista 7050s support 100 Mb/s on their copper sfp I have leveraged that, if you can break out the 40Gb/s ports you have as many as 64 ports of 10Gb/s. there are other switches that I've seen do this but they're not common.
For some reason it's becoming quite rare for SFP port to natively support 10M and 100M rates.
Technically obviously solution to me would be subrate SFP, which presents itself as 1GE to host, offering 100M or 10M to client. This would obviously break QoS at the host as host would still think it's 1GE and SFP itself would need to drop+buffer. But for my applications it would be fine, the 10M or 100M ports are typical some MGMT access interfaces. I can't imagine such SFP being complex or expensive, considering we have E1 over IP in a SFP, which includes control-plane and forwarding-plane inside SFP form-factor
Is this demand peculiar? Could I source such SFP somewhere by showing
My problem is mostly around PDU/CDU management, in racks that otherwise would be 10Gb/s only and in general I've addressed it with dedicated switches that support many of these devices rather than just two. there
is demand?
Putting 2 port switches or fibre converters with external PSU just to support few ports seem dirty.
-- ++ytti