Re: nhrp-05 ????? - Destination Prefix Extension

[Bruce Cole <[e-mail]>]

> I understand this to mean the NHS can ignore the extension (meaning in
> the Request packet only).  I thought the reason that an extension was
> put into a Request packet was because the client supported that
> extension.  The above text says, "if the *NHS* does not recognize..."
> Is there another section of the draft that I need to read where it
> indicates that a client can put a discretionary extension in a Request
> packet but ignore it when receiving the extension in the Reply packet?
> 
> If the client can ignore the extension on a purge and at the same time
> put the extension in the Request packet, then why should a server
> ever send a purge?

Discretionary means that the extension need not be implemented/handled by
all implementations.  The spec does not say anything about when a station
must/must not ignore such an extension.

So the spec does not preclude a client placing such an extension in a
request and ignoring it in the corresponding reply.  Sure, that may not
be too sensible, but the protocol need not be extended to police
this.

The use of the term NHS in the description of discretionary is incorrect.
Take for example a vendor private extension which is being added by the
NHRP responding station.  The station which receives this response may
ignore the extension, due to the discretionary bit, and that station may
or may not be an NHS.  So I recommend replacing 'NHS' with 'station' or
some such, in the description of discretionary.