Subject: RE: your mail

From: Shahram Davari <[email-masked]>
Date: Mon, 22 Jul 2002 13:47:47 -0700

Hi Eric,

If I understand you correctly, what you are saying is that assume a number
such as "N", and hash the Nth label, regardless of whether it is the 
real bottom-most label (i.e. with S=1) or not. If so then:

1) How do you know that at least N labels exist in all packets?
2) The Nth label can not identify a flow by itself, rather you need to hash the whole label stack from the top, up to the Nth label, in order to identify a flow.
3) I have heard that some implementations hash the IP header too? How does that fit in to your model? How do you know that the payload is IP? And don't you need to find the real bottom of stack (S=1) in order to include the IP header in the hash?

Yours,
-Shahram

> -----Original Message-----
> From: Eric Rosen [mailto:[email-masked]]
> Sent: Monday, July 22, 2002 3:15 PM
> To: Shahram Davari
> Cc: 'Giles Heron'; [email-masked]; [email-masked];
> [email-masked]
> Subject: Re: your mail 
> 
> 
> 
> Shahram> "Deep" or "not deep"  you need potentially unlimited 
> packet parsing
> Shahram> (uo to  MTU size), since as you  said the number of  
> labels are not
> Shahram> limited to 2. 
> 
> To  the MTU  size?   That would  be for  the  case where  the 
> entire  packet
> contains the MPLS label stack and there is no payload?
> 
> As has been made  clear repeatedly, you can hash on any  
> label, you just get
> more fine-grained load balancing the  further down you go.  
> So generally you
> would look  at the  bottom-most label  that you can  easily 
> see,  given your
> particular forwarding architecture. 
> 
> 
> 
>