[j-nsp] packet flow

[Janto Cin]

Hi Steve,
Is that mean after packets are sent across all FPCs then
the router gather all "sprayed" J-cells from all FPCs to reassembly the
packet again?
Thanks,
Janto
----- Original Message -----
From: "Steve Holman" <sholman at juniper.net>
To: "Janto Cin" <jantocin at datacomm.co.id>; <juniper-nsp at puck.nether.net>
Sent: Thursday, March 04, 2004 12:02 PM
Subject: RE: [j-nsp] packet flow


Hi Janto,

The J-cells are sent to the FPCs for packet buffering prior to
retransmission out the egress port.  Once the packets are ready for
retransmission they are reassembled into their original form and content
with the exception of the link layer header, which is added after the
packet is reassembled. The packet is then sent out the egress port.

As you note, packets are sent or "sprayed" across all FPCs in a
round-robin fashion.  Once the ASIC has finished one round it begins all
over again, overwriting any previous packets stored in memory.  However,
these previous stored packets have already "left the building" so it's
not a problem overwriting them.

HTH,
Steve

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Janto Cin
> Sent: Wednesday, March 03, 2004 8:08 PM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] packet flow
>
>
> Hi All,
>
> Just read the packet flow section in Sybex JNCIA book and
> curious about why the Inbound DBM ASIC have to send the
> packet's J-cells to all FPCs in the router on a round-robin
> basis? After done that, are the J-cells in the shared memory
> pool deleted? Thanks. -Janto
>
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