Attempting the impossible........?

[Richard Tapley]

Hi,

I wonder if someone could confirm if I have been asked to try the impossible.

We have 2 servers with a NIC with dual 10GB links in each which have RJ45 ports. They need to connect to 2 switches at 10GB we will then have 20 other servers connecting at 1GB.

We are using existing Cisco 3850 switches with 4 port SFP modules which have 2 x 10GB links.

I can't seem to find an SFP+ (10GB) module that will take RJ45 that is compatible with the switch, does one exist?

My fear is the only available option is to replace the network cards with ones that take SFP's and use the SFP modules with integrated cables, if there any other options?

Huge thank you to anyone that can help with anything that I might have missed...

[Reza Sharifi]

Richard,

I can't seem to find an SFP+ (10GB) module that will take RJ45 that is compatible with the switch, does one exist?

Sorry, there is no equivalent to GLC-T, which is a copper interface for gig.

I am surprised that your servers don't come with fiber NICs as well as the copper ones, as most vendors still use fiber NICs for 10Gig connectivity.

What is the distance between the switch and the servers?  If you replace your copper NICs with fiber maybe you can use Twinax cables if the distance is less than 10 meters.

Here is the other thing, Cisco is coming up with a new 3850 that has 24 ports 1/10 copper interfaces.  So you could replace the switch but that is probably more costly than replacing the NICs.

Thanks,

[Richard Tapley]

Hi Reza,

Thanks for the reply.

I asked a supplier about a 10GB RJ45 ~SFP+ module and the part number they gave me with a google search showed something that wasn't even an SFP so not sure what that was maybe a zenpack (sorry not sure of spelling).

The server was spec'd by our server specialist so I am not sure if it was specifically chosen but he has mentioned that he thought it was what the manager wanted but could have been confusion.

At the moment I am not exactly sure if the distance between servers and switches but as they are both new I am pretty sure it will be under 10m, so I will look at Twinax cables.

We were going to buy switches but have since been told we can use switches originally bought for another project and then replace them hence the use of the Cisco 3850's.

As we have the switches already I am thinking it might be easier to replace the network cards with ones that accept the cables with the SFP modules built in as they seem to specify 1m, 3m, 5m if I understand correctly. The part numbers that I have found websites say are compatible are as follows:

SFP-H10GB-CU1M
SFP-H10GB-CU3M
SFP-H10GB-CU5M

Would this be something that you would recommend?

Thanks again for your reply, I hope I am on the right track.

[Reza Sharifi]

Hi Richard,

Yes, these are the correct part numbers for the cables and according to this link as long as you are running IOS XE 3.2.0SE it should work. I personally have never used Twinax on the 3850s.

http://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/10GE_Tx_Matrix.html

Also, if you have not purchased the switch yet, I recommend looking at the Nexus series switches, as they are designed for high speed and low latency connectivity with servers, VM, storage, etc.. The 3850 series switches are designed for campus area (user) network and not  for server or storage connectivity. Also, if you use the 10Gig to connect the 3850 to servers, you really don't have any other high speed ports for your uplinks.

data sheet for Nexus:

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/data_sheet_c78-618603.html

HTH

[Richard Tapley]

Hi Reza,

Thanks again for the reply.

I will check the IOS on the switches we have got thanks for the note on that.

When I was researching I looked at a couple of Nexus switches but was told they were far too expensive , if we do actually get the 3850 I consider myself lucky as originally we were looking at 2960's.

I am keen to try and obtain the right kit for the job but sometimes mony is the problem as I am sure it is for others.

Could there be a problem with the 3850's with regards latency?

I sadly have no experience yet on the Nexus switches so am going to struggle to justify them as an option. Is there any basic documentation that you would reccomend to understand the basics?

( E.g.  I looked at the Nexus 2000 switches and they mentioned using a Nexus 5000 as a parent switch and currently I don't fully understand the need for a parent switch or whether it is compulsory?)

Many thanks for your assistance with this.