[j-nsp] packet flow

[Gary Tate]

This is not entirely easy to say.  But in general yes.  J-Cells in fpc 
memory are data cells.  Encaps and headers are built by the system 
depending on user configuration etc.  For example TOX bits in the 
header will be rewritten depending on COS config. Is this what you are 
asking?
Gary

On Mar 5, 2004, at 1:39 AM, Janto Cin wrote:

> Is the notification and result cell only consist of header?
> And the J-cell packet consist of payload?
> TIA,
> 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 12:33 PM
> Subject: RE: [j-nsp] packet flow
>
>
> 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
>>>
>>
>>
>
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