[j-nsp] M10i FPC PIC Throughput Questions

[Matt Bentley]

Thanks!  So it would be correct to say you should NEVER see
oversubscription on a channelized DS3 card right?  Obviously, you can
overdrive a single T1, but you'd never see drops due to the PIC itself?  I
guess what I'm asking is whether or not the bandwidth availalble on a FPC
is allocated equally per PIC, or if everyone sort of shares it.

On Sat, Feb 23, 2013 at 8:13 PM, Christopher E. Brown <
chris.brown at acsalaska.net> wrote:

>
> With the std cfeb after internal overhead per bus capacity is 3.2Gbit of
> traffic, this is worst case minimum small packets, etc.
>
> Raw bus capacity is IIRC ~ 4Gbit, difference is overhead.
>
> Unless you are doing all small packet, actual limit is higher than 3.2.
>
> Enhanced CFEB bumps the raw bus capacity to something around 5Gbit, and
> the after all overheads forwarding capacity to 4Gbit (based on the 1G
> per PIC limit).
>
> Summ...
>
> CFEB
>         Up to 1Gbit per PIC, 3.2Gbit per bus _worst case small packet_
>
> E-CFEB
>         Up to 1Gbit per PIC
>
>
> These figures are
> On 2/23/13 6:01 PM, Matt Bentley wrote:
> > OK - so there has been a lot of discussion around this that I've seen,
> but
> > I've searched for hours and still can't find concrete answers.  Can
> someone
> > help?
> >
> > 1.  Does the 3.2 Gbps throughput limitation include overhead?  In other
> > words, Is the "raw" throughput 4 Gbps with effective throughput of 3.2
> > Gbps?  Or is it 3.2 Gbps of raw throughput with effective throughput of
> 2.5
> > Gbps?
> > 2.  Is this throughput per PIC on the FPC?  So let's say I have three 4x
> > GigE IQ2 PICs and one channelized DS3 IQ PIC.  Does each PIC get
> bandwidth
> > allocated equally between them?  So is it 800 Mbps per PIC, and the PICs
> > can't "steal" bandwidth from another one?
> > 3.  Where, and based on what, is traffic dropped with  Juniper head of
> line
> > blocking (ie where multiple high speed input interfaces try to go out the
> > same lower speed exit interface)?
> >
> > Thanks very much!
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>
>
> --
> ------------------------------------------------------------------------
> Christopher E. Brown   <chris.brown at acsalaska.net>   desk (907) 550-8393
>                                                      cell (907) 632-8492
> IP Engineer - ACS
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