Subject: RE: interpretation of bucket size in intserv flowspecs, by hosts

From: Yoram Bernet <[email-masked]>
Date: Tue, 31 Mar 1998 23:26:24 -0800

[Yoram Bernet]  thanks... below...
> -----Original Message-----
> From:	Craig Partridge [SMTP:[email-masked]]
> Sent:	Tuesday, March 31, 1998 9:58 AM
> To:	Yoram Bernet
> Cc:	[email-masked]
> Subject:	Re: interpretation of bucket size in intserv flowspecs, by
> hosts 
> 
> 
> In message
> <[email-masked]
> om>, Yoram Bernet writes:
> 
> >The problem arises when we consider the token bucket size parameter. If
> the
> >token bucket size is smaller than the MTU size. Then, if an app submits a
> >packet which is greater than the bucket size, there is nothing that we
> can
> >do in the shaper to make it compliant (since the smallest thing we can
> send
> >on the wire, is a packet, which is greater than the bucket size).
> 
> The app is not supposed to submit a packet larger than the MTU of
> the flow, and the bucket size should be larger than the MTU of the flow.
> So this shouldn't occur.
[Yoram Bernet]  Maybe the problems arise from wanting to use the same
parameters for both a policer and a shaper. Consider the following case in
which i want the bucket size to be smaller than the mtu of the flow:

1. my mtu is 1500 bytes.
2. i want my shaper to generate a smooth audio flow of evenly spaced, 40
byte audio packets...

then, the bucket size i feed to my shaper is 40 bytes. as long as my app
submits 40 byte packets to the shaper, the right things happen. the app can
be bursty, the shaper will sort it out. however, if my app slips an 80 byte
packet to my shaper - what do i do then? strictly speaking, i mustn't send
it and there's nothing i can do in the shaper to fix it. as a number of
people have pointed out, in a practical implementation, i could allow bursts
in excess of bucket size if they are due to the fact that the burst is a
single packet, so long as i delay the next packet, and from packet to
packet, still conform to the parameters...

> Craig

---

From: Craig Partridge <[email-masked]>
Date: Wed, 01 Apr 1998 08:04:51 -0800

>2. i want my shaper to generate a smooth audio flow of evenly spaced, 40

Then write an application shaper that generates 40 byte packets.  The
purpose of the Int Serv token bucket is not to shape, but to describe.

Craig

---

From: Gang Duan <[email-masked]>
Date: Mon, 13 Apr 1998 16:21:10 -0400 (EDT)

I am not sure why MOSPF must use OSPF as its unicast protocol and DVMRP
must use RIP, but PIM doesn't need any.

Thank you.