[j-nsp] Memory Allocation per FPC

[The Drifter]

Hannes,
I have been waiting patiently, Many thanks for this description. It is very 
useful, correct me if i am wrong below:

1. the hardware configuration on the box is Independent of the performance 
of the router & I can stick in PICs anywhere

2. Also even if I am using only 2 FPCs, I can get more performance if I plug 
in All the FPCs

3. Can you please goint me to FPC types/memory-size  link, for M-series 
routers??

3. I wouldn't mind getting more information on dynamic/static allocation, at 
all  ;)

Regards,
Jimmy

>From: Hannes Gredler <hannes at juniper.net>
>To: The Drifter <prophecy_68 at hotmail.com>
>CC: juniper-nsp at puck.nether.net
>Subject: Re: [j-nsp] Memory Allocation per FPC
>Date: Sun, 8 May 2005 09:53:01 +0200
>
>each stream (= a port on a PIC) will be assigned a buffer space
>equal to 200ms (m-series) and 100ms (t-series) of bandwidth-delay
>product so a STM-4 does consume 622/8*0.2 = 15.55MB buffers space;
>
>now the difficult part:
>
>the buffer is not statically allocated to a single FPC but rather
>to the pooled memory of all FPCs on a PFE. also the packet itself
>will be sprayed in quantums of 64-bytes called j-cells across
>the contributing FPC SRAMs; so for example it would well be
>that a 250 bytes packet enters the router on FPC0 and its
>fragments are stored on FPC{1,2,3,4}; on the egress stage
>the packets are reassembled and passed to the I/O manager ASIC
>for queuing/rewrite etc.
>
>the difficult^2 part:
>is not a pure static allocation but also has a dynamic component;
>however the application/purpose of static/dynamic allocation
>i believe would go beyond what you have been asking, right ;-)
>
>/hannes
>
>On Mon, May 02, 2005 at 12:49:07PM +0000, The Drifter wrote:
>| How is the memory of an FPC allocated per PIC. Is it allocated equally 
>per
>| each PIC? Or is it allocated by the Buffer Manager (PFE) per data packet
>| received?
>| Therefore a STM4 PIC will useup more memory of the FPC then a DS-3 PIC?

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