Cisco Nexus 2248TP + 5596UP Unboxing and Physical Chassis Comments

I received a shipment of several Cisco Nexus 2248TP Fabric Extenders as well as a pair of Nexus 5596UP switches. I unboxed them and took a few pictures to note how things were going. Comments for each shot follow below each one.

I’ll get into design and implementation of the Nexus gear in separate posts in upcoming weeks. I don’t have to rush these into production, so I’m hoping to work with some of my fellow engineers to put the Nexus gear through their considerable paces in a lab setting before we rack ’em up permanently.

We ordered a Nexus bundle from Cisco that contained a 5596UP, 6 2248TP Fabric Extenders, and 48 FETs (a FET being a low-cost optical module that interconnects the 2Ks to the 5Ks or 7Ks, but isn’t good for much else). The FETs were scattered all over the box, as the plastic tray in the upper right of the shot had popped open, allowing many of the 36 FETs inside to disperse. No FETs were missing, and none of them appeared to be damaged. As the FET is like any other SFP form factor transceiver, it’s a rugged little device surrounded by metal. I’m not expecting any issues, but a simple piece of tape could have kept the plastic tray shut. One of my tweeps ran into the same issue only in his case, several of the FETs ended up missing.

The 5596UPs are deep. This is a side view of a pair of them, with a Cisco 2911 ISR G2 stacked on top for scale.

This is a close up of one of the 16 fixed port groups on a 5596UP. Note that on the top row, the SFPs are inserted in a manner you would probably consider “normal” (the card edge facing downward). However, on the bottom row, the SFPs face up.

This is a shot from the side/front of a stack of fabric extenders. I want to point out the downward sloping gap that forms an air exit point.

Here again, a shot showing the gap that allows air to exit in the front-to-back airflow design optimized for hot/cold aisle data centers.

A FET is not a regular Ethernet transceiver. It’s a low cost way to uplink a 2K. Don’t mistake this for a 10G SR optical module.

The fabric extender is not a switch. Without a 5K or 7K, it’s functionless. Think of it as a linecard in a logical chassis where a 5K or 7K is the necessary component.  In this shot, I’ve got rack ears mounted to the front (the furthest away from us here), a rail guide mounted further back, and the rail floating in the guide. In production, the rail will get mounted into the cabinet, and then the FEX will get slid onto the rail, and then the front rack ears screwed into place.

Same shot as above, just the rails slid along the rail guide so that you can see which bit is floating.

The 2248TP FEXen have field-replaceable modular fans and power supplies. Here, I’ve pulled out the fan unit and sat it next to a screwdriver for scale.

Here’s the 2248TP fan unit partially seated in the chassis. On either side is a power supply. The fan unit is secured with two thumb screws.

Here is one of the power supplies from the 2248TP FEX.

Here’s a power supply from the 2248TP partially seated in the chassis. The power supplies are held in place by clips.

More to come as I get into the Nexus lab testing.


  1. says

    After installing 4 x Nexus 5548P and 6 x Nexus 2224TP units, then having to relocate them, i must say i really hate the process of rack mounting them.
    I wish they were as nice to mount as most 1RU servers with ‘quick mount’ rails.

  2. says

    Make sure none of your kit is bent!  At my last place I installed a pair of MDS9148s (similar chassis design to some of the Nexus gear and uses the same stupid rails) only to find after much struggling that one of the switches was bent – you could put it on the ground and rock it from side to side as it had a very slight curve to it.  Needless to say that was sent for RMA…

    • says

      I was disappointed in the flex of the outer shell of the Nexus gear. It’s not very stiff overall. I assume this compromise in the overall design was to help cope with weight. Bending one would be easy under the right circumstances. I noticed a rounded gap beneath the fan assembly on the 2248TPs, for instance.

      • Norgs says

        I have a bunch of 2232’s that have the fan tray ‘sag’.  With the PSU’s and the fan tray out, the chassis is a very thin piece of metal.

        If you are in a situation where you have 4 2232’s on top of each other, the weight of the top ones makes for a nice smiley face on the very bottom unit when looking at the fan tray.

  3. says

    I hate to say it, but I have to mention I think your rails are on backwards in that photo Ethan… I’ve always mounted the fixed set on the port side (so you ensure it’s right against the edge) and the sliding set on the back, since you don’t really care where it mounts…

    • says

      Yes, I completely agree – the rack these are going into is tight, and I may or may not end up mounting them this way, just depending. I might have to do exactly what you’re saying to make it work.

  4. chrismarget says

    Backward rails?

    Ethan – You’ve actually got the rails mounted in exactly the way the install guide recommends.  Mounting the FEX flush with the front of the servers seems crazy, but works around an airflow problem.  Here’s a snapshot from the install guide:

    If you don’t know about the airflow problem, see here and proceed with caution:

    Flimsy Nexus chassis?  Yeah, the 5548s actually droop under their own weight.  Crazy.

  5. Dean Weeks says

    I understand the these switches support Front-to-Back or Back-to-Front airflow configurations, depending on the power supplies and fan tray used. Thus the rails may be one way or another. The rail placement illustrated by Ethan suggests to me a Back-to-Front flow is desired. So my question to Ethan is, do you have black stripe or no black stripe?

    From Cisco:•Make sure that the fan tray and power supply modules all use the same direction of airflow. All of the modules should have no black stripe (front-to-back airflow) or all of the modules should have a black stripe (back-to-front airflow). 

    I’m looking forward to receiving my N2K-C2248TP in a few more months.

  6. Jamie says

    Sorry to drag up an old post, but do you find problems with air flow when the 2k’s are mounted at the rear of the cab? what i mean is, with this rails, you are using a u space at the front of the cab also. as this is in a cold asile containment, we are having problems with air leaking through the gap this creates.

    • says


      I’ve had problems with the short depth of the FEX when they’re mounted aligned with the hot end of the cabinet. There are two ducting fixes for this problem: Panduit CDE-2 and Cisco NXA-AIRFLOW-SLV=.

      My environment didn’t include a containment scheme, just hot/cold aisles. The open space at the cold side of the rack winds up as a hot air exhaust (backward airflow) because of the gap. I think this is what you’re describing.

      Info about the Cisco fix is here:

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