CRS-1 8-slot physicals

6 07 2007

Following a question from Richard about the 8-slot version of the CRS-1, here’s some of what I gleaned last week.

As you may know, the Carrier Routing System 1 (CRS-1) comes in a 16 slot, 8 slot and 4 slot format.  Currently only the 16-slot ones can be can be chained together to become the kind of super-node that I wrote about in my previous post.  The 16-slot one is pretty massive though, so may people on the course seemed to be about to put 8-slot variants in for their customers.

Even though this unit is only a half rack in size, you still need to do a site survey before installing it.  Here are the vital statistics on the 8-slot:

  • Dimensions 44.5 x 93 x 97.8 cm (w x d x h) or 17.5 x 36.6 x 38.5 inches (w x d x h) 
  • Chassis needs 101cm (40 inches) in the rack
  • You need 122cm (48 inches) clear space front and back for access
  • As-shipped weight of chassis = 138Kg (331lb)
  • Chassis plus packaging weight = 190Kg (418lb)
  • Fully loaded weight is around 275Kg (600 lb)
  • Maximum floor loading = 0.7Kg/cm2 (133lb/square foot)
  • BTUs – 27,350 BTU per hour
  • Power requirements 8kW DC or 8.75kW AC.

The chassis is a midplane-based one (as per the 16-slot).  The front side is termed the “PLIM side” and the rear side is called the “MSC side”.

As shipped, the chassis is delivered with blank plates installed in all the slots.  These don’t just fill up the holes – they are important for maintaining the rigidity of the chassis.  So if you are tempted to remove them to reduce the weight of the chassis while you move it into position, Cisco advise strongly against this.  The top fan tray may be removed though to aid installation.

The chassis is a 2-man install, but you are probably well advised to use one of those jackable trucks to get it up to the right height.   Two L-shaped rails are supplied which need to be installed in the rack before you try to put the CRS-1 in.     There are yellow metal “pulls” that come attached to the chassis to help you with the lift.   These should be removed once it is in the rack.

The rack that the CRS-1 is going into should be attached to the floor correctly.  Apparently do special parts for the CRS-1, although I’ve looked on both their US and UK sites and I can’t see the appropriate parts.   I’m sure Cisco’s professional services people can advise on what you need. You should also verify that the floor can withstand the weight of a fully-loaded chassis.

Note that you may need to remove the front or rear mounting rails to do the installation, depending on which direction you are installing it in.  There are two types of screws that are used to attach these rails – a set of hex-head screws and a set #1 phillips.    The phillips are apparently very easy to round off, or drop into the chassis, so be careful when removing these.

Line cards area called PLIMs (Physical Line Interface Modules) and go in the front.   Each PLIM marries up with a corresponding MSC card that is inserted in the rear of the chassis.  

In the middle two slots are installed the Route Processors, as you’d expect. These present the usual  interfaces for console and management ethernet.  There are two external clocking interfaces on the RPs but these are unused at the moment.

The air filter is installed from the front, as are the two AC rectifiers or DC power entry modules.  Cabling of the rectifiers or PEMs is done at the back, however.

Finally, there is a kind of telescoping fibre management system above the slots which looks well thought out.

Advice from the more experienced on the course I was on was that you should be careful when inserting any cards, but in particular you should be very careful with the RPs.  There is a chance you can strip off the thread in the chassis if you’re not inserting these properly.  You don’t want to have to RMA a chassis now, do you?

At the rear, you get access to the fan trays.  As with the 16-slot, the system will run on only one fan tray, but if both are removed or fail, it will shut itself down to protect itself.  The top tray pulls air in from the air filter at the bottom of the PLIM side.  The air rises up over the cards and the bottom fan tray pulls it back down over the cards at the rear, blowing it out at the bottom of the chassis.

There are slots for up to 8 MSCs, which need to be installed on a 1 to 1 ratio with the PLIMs at the front.   There is only one type of MSC card.

In the middle of the chassis on the MSC side is where you install the switch fabric cards.  There are four of these, and they provide 2 data planes each, connecting to every MSC in the chassis (a total of 8 data planes).  The switch fabric is not a cross-bar but a new kind of switching architecture called a Benes switch.  I’ll write that up later – it is a reasonably complex subject.

There are some very good multimedia presentations on the Cisco Partner E-Learning site with regard to the installations of the CRS-1.  I think they’re sometimes a bit over-flash with the animations to be honest – this isn’t some kind of sci-fi movie we’re watching!   All the same, at least you get to see the thing in “3D”.

Have a look at this link if you are registered as a partner. (Login required)



2 responses

13 07 2007
Geoff Nixon

Hi. Was doing a bit of Internet based reminiscing and came across your blog, very nice. Hope things are going well for you. I am pretty settled back in to NZ life after 5 years away, just bought a house that we are moving in to this weekend.
Anyway, reading /. today I came across this article – which is interesting in itself, but then checking out the pics –;dir=20070708 shows that they used a CRS-1 (4 slot?) at the “Mum’s End” of the equation. It does look like a beast – and it is confirmed by reading the label on the middle PLIM!!
Not sure if they quite followed the installation instructions though….
All the best!!

13 07 2007

Hi Geoff!
It’s good to hear from you – and glad to hear you’re settling back in over there. Things are going OK over here – some interesting training going on at least, even though we’ve not had to put any of these things in yet.

I love those pictures! The thing’s just in a shed, isn’t it? Along with a lawnmower, some antiques and probably running off an overloaded extension cable… Even the 4-slot is pretty huge, and I imagine it heats up the shed quite nicely.

Take care – and all the best to you both.

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