Re: enable/disable subnet mask service on IOS

From: James Ventre (messageboard@ventrefamily.com)
Date: Thu Feb 03 2005 - 22:26:42 GMT-3


 Sounds like an ICMP Mask Request
http://www.networksorcery.com/enp/protocol/icmp/msg17.htm

RFC 950, page 11:

  A gateway receiving an address mask request should return it with the
  address mask field set to the 32-bit mask of the bits identifying the
  subnet and network, for the subnet on which the request was received.

  If the requesting host does not know its own IP address, it may leave
  the source field zero; the reply should then be broadcast. However,
  this approach should be avoided if at all possible, since it
  increases the superfluous broadcast load on the network. Even when
  the replies are broadcast, since there is only one possible address
  mask for a subnet, there is no need to match requests with replies.
  The "Identifier" and "Sequence Number" fields can be ignored.

James

Tony Schaffran wrote:

  Does this have anyting to do with classfull and classless routing protocols?



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