[EMAIL PROTECTED] wrote:
> I agree with Pekka that this compllicates the text and the > implementation. Moreover, N (the long-term average) can be > in number of packets per seconds or a fraction of the attached > link's bandwidth. Don't you think, the size of the packet > will be covered if N is specified as the fraction of the > bandwidth ?
I'll let the other stuff go for now, but the above is a very important point and in need of a bit more discussion. The token bucket text we are discussing essentially recommends that nodes implement a virtual queue for outgoing ICMPv6 error messages and perform active queue management on that queue based on the parameters N and B.
RFC 2309 recommends active queue management for *routers*, but the text we are talking about correctly goes the extra measure of recommending active queue management at the source of the ICMPv6 error messages itself, i.e., the "0th hop router". RFC 2309, section 3(b) says:
Note: the decision whether or not to drop an incoming packet can be made in "packet mode", ignoring packet sizes, or in "byte mode", taking into account the size of the incoming packet. The performance implications of the choice between packet mode or byte mode is discussed further in [Floyd97].
So IMO (and based on the RFC 2309 text) an active queue management recommendation that neglects "byte mode" and fails to cite RFC 2309 as informative text would be omitting important considerations that implementors should take into account. As such, I suggest the following:
A recommended method for implementing the rate-limiting
function is a token bucket, limiting the average rate of
transmission to N, where N can either be packets/second or a
fraction of the attached link's bandwidth, but allowing up to
B error messages/bytes to be transmitted in a burst, as long
as the long-term average is not exceeded. Other methods that
provide effective active queue management [RFC2309] for
outgoing ICMPv6 error messages are also acceptable.Fred L. Templin [EMAIL PROTECTED]
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