From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jim Fleming" Subject: Re: Setting and Routing on the TOS Source (SRC) and Destination (DST) Bits Date: Sun, 22 Sep 2002 10:18:23 -0500 Sender: netfilter-admin@lists.netfilter.org Message-ID: <0cb501c2624b$4b4864a0$c6b22543@repligate> References: <20020922134852.PSNX6699.mta01-svc.ntlworld.com@there> <001d01c26242$79813670$026410ac@honor> <20020922142038.LIRG2092.mta07-svc.ntlworld.com@there> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Errors-To: netfilter-admin@lists.netfilter.org List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: Antony Stone , netfilter@lists.netfilter.org ----- Original Message ----- From: "Antony Stone" > > Sorry :-) You're right. I just hate to see bullshit spread about in what > is usually a very helpful and informative mailing list. > I think that is an extreme ( = unreasonable ) point of view. Of the 160 bits in an IPv4 header, **YOU** really do not see how **you** could reasonably use these 49 for routing purposes: 4 bits - header length 16 bits - fragment identifier 13 bits - fragmentation offset 16 bits - header checksum Of the remaining 111 bits, even these 28 would be a challenge to use intelligently for routing, **YOU** think ? 4 bits - IP version no 16 bits - total packet length 8 bits - time to live The length and the ttl might make sense as numeric values, but not as bitmasks for routing decisions. **YOU** think it's much fairer to say that of the 160 bits in the IPv4 header, 83 of them make sense for routing purposes: 8 bits - type of service 3 bits - fragmentation flags 8 bits - protocol identifier 32 bits - source address 32 bits - destination address ======= Other people also have a right to think...and do as they please with the 160 bits... There are... 1.4615016373309029182036848327163e+48 ...possible 160 bit headers....all of them may not be useful.... NetFilter allows each person to decide which are useful and which are not... ...educated people know what is in those 160 bits...and how they can be used... http://www.netfilter.org/ An ISP that does not pass TOS Field end-to-end with no change, is not an ISP... An ISP that sets the TOS Field for you is not an ISP... By the way, there are only 2 bits used for Fragmentation Flags...MF and DF... What do **YOU** use the Spare Bit for ?