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 09:39:35 -0500 Sender: netfilter-admin@lists.netfilter.org Message-ID: <0c8101c26245$dfe72c50$c6b22543@repligate> References: <20020922082118.EQR13996.mta05-svc.ntlworld.com@there> <0c0601c2623c$f82fd7c0$c6b22543@repligate> <20020922134852.PSNX6699.mta01-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" > On Sunday 22 September 2002 2:35 pm, Jim Fleming wrote: > > > Have you ever calculated how much bandwidth is wasted each year > > with 4 of the 160 bits in every packet as useless ? > > Actually, it's 4 of every 160 bits in the *header* - there's up to another > 1500 *bytes* (on ethernet) of body in the packet as well, so the wasted > bandwidth varies from 4/160 = 2.5% for empty packets, to 4/12160 = 0.03% for > full ones. > Are there also 4 bits in each 320 bit header, when the value is 0110 ? Is that an improvement ?....with 4/320 = 1.25% Can routing be done on the values 0100 and 0110 ? Are those 4 bits included in your count of useless routing bits ? From: "Antony Stone" "I still say that 83 of them make sense, 28 are doubtful, and 49 are useless. ============================= Moving to the next 4 bits....do you agree they are almost always 0101 (5) ? IF one assumed they did not care about "options", could those bits be assumed ?...and dropped ? Is that another 2.5% savings ? If the 0100 and the 0101 are tossed, is that a 5% savings ? ...or, could the 0100.0101 be considered an 8 bit "version" number ? do people want or need 256 versions ? ========== Going back to the mention of the *header*....could the 4-bits really be a header ? ...are all 16 values valid ?....what is 0000 and 0001 ? Does the 4-bit "Version Header" describe the "Next Header" which follows ? 0000 = 0 bit header 0001 = ?? ... 0100 = 160 bit header ... 0110 = 320 bit header =========== Does NetFilter route based on the first 4 bits ? http://www.netfilter.org/