[j-nsp] Memory Allocation per FPC

[The Drifter]

We are running an M20 with
2xSTM-16 cards. (FPC0, FPC1)
3x4OC-3 cards (FPC2)
We need to add 4xGE cards.
So, I am thinking if the architecture permits Pooling of FPC resources to 
release enough memory+switching power to allow adding the 4xGE cards.

Thanks,
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: Mon, 9 May 2005 00:27:12 +0200
>
>On Sun, May 08, 2005 at 08:34:17AM +0000, The Drifter wrote:
>| 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
>
>correct no PIC dependencies wrt performance;
>
>| 2. Also even if I am using only 2 FPCs, I can get more performance if I
>| plug in All the FPCs
>
>not correct - each FPC1 supports a "fabric" bandwidth of 3.2Gbps for user 
>data;
>an additonal FPC increates the aggregate fabric bandwith, howver it also
>has to support more PICs then ....
>
>| 3. Can you please goint me to FPC types/memory-size  link, for M-series
>| routers??
>
>--->just issue a "show chassis fpc detail" and watch the SDRAM portion
>--->example taken froma M10i FEB
>Slot 0 information:
>   State                               Online
>   Logical slot                      0
>   Total CPU DRAM                  128 MB
>   Total SRAM                        4 MB
>   Total SDRAM                      64 MB
>   Total notification SDRAM         12 MB
>   I/O Manager ASIC information        Version 3.1, Foundry IBM, Part 
>number 0
>   Start time                          2005-04-19 09:53:39 CEST
>   Uptime                              19 days, 14 hours, 27 minutes, 46 
>seconds
>
>| 3. I wouldn't mind getting more information on dynamic/static allocation,
>| at all  ;)
>
>well, what is the problem you're trying to solve ? and why is knowledge
>of our mem allocation relvant to it ?
>
>/hannes
>
>
>| >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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>
>--
>_____________________________________________________
>hannes gredler             mobile: +43 676 9380638
>network support engineer    email: hannes at juniper.net
>juniper networks inc.,      skype: hannesgredler9000

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