[j-nsp] MX480 DC Power

[Bjorn Tore Paulen]

Gents

On a MX480 The lower 4 linecards are feeded by power 0 and 1, the upper 4
are feeded by power 2 and 3. The doc claims that you always have to have
power on either {PEM0,PEM1} or {PEM2,PEM3}. We use A+B power, and connect
the A side to PEM0 and PEM2, and the B side to PEM1 and PEM3. So if either
fails, the whole chassis has power.

DC Power 	Redundant Power 	Power Supply Provides Power to the
Following Components
supply   	supply
PEM0		PEM1			Fan tray, DPC slots 0 and 1, and SCB
slots 0 and 1
PEM1		PEM0			Fan tray, DPC slots 0 and 1, and SCB
slots 0 and 1
PEM2		PEM3			Fan tray and DPC slots 2 through 5
PEM3		PEM2			Fan tray and DPC slots 2 through 5

 
/BT

> -----Opprinnelig melding-----
> Fra: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] På vegne av Ernie Rubi
> Sendt: 18. mars 2009 18:49
> Til: Matt Yaklin
> Kopi: juniper-nsp at puck.nether.net
> Emne: Re: [j-nsp] MX480 DC Power
> 
> Thanks, this is very helpful indeed.
> On Mar 18, 2009, at 1:48 PM, Matt Yaklin wrote:
> 
> >
> >
> > On Wed, 18 Mar 2009, Ernie Rubi wrote:
> >
> >> Thanks, a quick read makes it look like we need 4 DC feeds to the 
> >> router in order to have it be redundant.
> >>
> >> We have only an A+B feed, so only 2 out of the 4 needed.
> >>
> >> If I operate this way, the power supplies won't be redundant?
> >>
> >> Also, what other info would you need to fully answer the 
> question?   
> >> We are going to be running 2 x 10GE as well as 6 GigE 
> interfaces on a 
> >> DPC line card plus redundant RE-2000s.
> >>
> >
> > Please keep in mind that I do not have a MX480. I own other Juniper 
> > gear.
> >
> > The missing information to me was the amount of power supplies.
> > I also understood the pdf as saying if you wanted 4 power 
> supplies you 
> > would need 4 feeds with each feed having 32 AMPs @ -48 VDC.
> >
> > The back contains 4 power supply slots. PEM0-3 they are called.
> > If you only have two power supplies you need to insert them in PEM0 
> > and PEM2 for example** (See below). If one fails you are down.
> >
> > With 4 power supplies you can have one each fail among PEM(0-1) and 
> > PEM (2-3). But if PEM(0-1) both fail you are down. This all assumes 
> > you are running a fully loaded chassis***(See below).
> >
> > Here is a pdf to help you out:
> >
> > 
> http://www.juniper.net/techpubs/hardware/mx480/fru-mx480-dc-power-supp
> > ly/fru-mx480-dc-power-supply.pdf
> >
> > **I am also not sure if the manual has a typo under "DC 
> Power Supply 
> > Configurations for the MX480 Router" where it states, "If 
> only two DC 
> > power supplies are installed, they must be installed in 
> slots PEM0 and
> > PEM1 or in slots PEM2 and PEM3." That really does not make 
> sense to me 
> > if you look at Table 1 and how they back each other up.
> >
> > ***Notice how the DPC slots 0 and 1 are powered by PEM(0-1) and DPC 
> > slots 2 through 5 and powered by PEM(2-3).
> >
> > I hope this helps.
> >
> > matt
> >
> >> Ernie
> >>
> >> On Mar 18, 2009, at 1:06 PM, Matt Yaklin wrote:
> >>
> >>> Here you go:
> >>> 
> http://www.juniper.net/techpubs/en_US/release-independent/junos/topi
> >>> cs/reference/specifications/mx480-power-components-dc.pdf
> >>> It seems it is hard to answer your question straight away 
> as we do 
> >>> not know enough information.
> >>> I hope that link helps.
> >>> matt
> >>> On Wed, 18 Mar 2009, Ernie Rubi wrote:
> >>>> Hi folks,
> >>>> I currently have a -48 vDC, 2 phase (A+B) 70 Amp (total) DC 
> >>>> circuit.
> >>>> I need to order an MX 480 with DC power, will the DC 
> circuit that I 
> >>>> currently have work?
> >>>> Thanks,
> >>>> Ernesto M. Rubi
> >>>> Sr. Network Engineer
> >>>> AMPATH/CIARA
> >>>> Florida International Univ, Miami
> >>>> Reply-to: ernesto at cs.fiu.edu
> >>>> Cell: 786-282-6783
> >>>> _______________________________________________
> >>>> juniper-nsp mailing list juniper-nsp at puck.nether.net 
> >>>> https://puck.nether.net/mailman/listinfo/juniper-nsp
> >>
> >>
> >>
> 
> Ernesto M. Rubi
> Sr. Network Engineer
> AMPATH/CIARA
> Florida International Univ, Miami
> Reply-to: ernesto at cs.fiu.edu
> Cell: 786-282-6783
> 
> 
> 
> 
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