Subject: WG Action - Reject [LL3] TTL=255 on send, check on receive?

From: Erik Guttman <[email-masked]>
Date: Fri, 11 Apr 2003 14:53:55 +0200 (CEST)

LL3:   TTL=255 on send, check on receive?

Decision: Reject
Action:   None

Notes:    This proposal requires setting TTL to a value which available
          for modification by higher level (application) interfaces.

          Legacy devices exist which do not send with TTL = 255, but
          otherwise comply with the specification.  It would be
          impossible to communicate with such devices if TTL != 255
          messages were dropped.  It is not clear *when* or under *which
          conditions* the dropping policy can be used safely in the
          future, based on this suggestion.

          The argument that router reconfiguration to not forward
          from LL sources or to LL destinations will take a while and
          may never be complete cannot be dismissed.

          It is also possible to send to a non-link-local multicast
          address from a link-local source.  Using flood and prune
          multicast routing algorithms, link-local sourced datagrams
          will be widely distributed on the network if TTL = 255.

          Arguments for security benefits for this protocol were
          not widely accepted.  Indeed many felt that assertions of
          this as a 'security feature' was pernicious and raised
          false expections.

Erik Guttman
Zeroconf WG chair