[j-nsp] packet flow

[Steve Holman]

Yes.  The packets are buffered in the memory on the FPCs while route
lookup determines the nexthop.  Once the nexthop for a given packet is
determined, the ASIC collected the J-cells from memory, reassembles the
packet and forwards it to the egress port.

Make sense?

Cheers,
Steve

> -----Original Message-----
> From: Janto Cin [mailto:jantocin at datacomm.co.id] 
> Sent: Wednesday, March 03, 2004 9:12 PM
> To: Steve Holman; juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] packet flow
> Importance: High
> 
> 
> 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
> >
> > _______________________________________________
> > juniper-nsp mailing list juniper-nsp at puck.nether.net 
> > http://puck.nether.net/mailman/listinfo/junipe> r-nsp
> >
> 
>