Some info I managed to gather. Thanks - Vish -----Original Message----- From: Arun Kumar Dheena [mailto:arunkumar.dheena@wipro.com] Sent: Friday, June 14, 2002 3:27 PM To: 'Vishwanathan K'; linux-cdc@kmcdc.wipro.com Subject: RE: [Linux-cdc] FW: Math in hashing funtions (routing code) The general hashing scheme used in routers is (s1*s2*s3*s4*d1*d2*d3*d4 ) Mod N Where * --> XOR operation and si, (i= 1 to 4) is the i-th octet of source IP address. The di is the destniation IP addr. XORing the IP address bits is a common hashing scheme. Check this out also "Performance of Hashing Based Schemes for Internet Load Balancing" by Zhiruo Cao et al. One funda behind using source IP address as input to hashing to route packets is to perform source IP address based filtering. regs arun -----Original Message----- From: linux-net-owner@vger.kernel.org [mailto:linux-net-owner@vger.kernel.org] On Behalf Of Amit Kucheria Sent: Thursday, June 13, 2002 3:24 PM To: linux-net@vger.kernel.org Subject: Math in hashing funtions (routing code) Hi, Could somebody point me to the mathemetical base (papers?) for the hashing functions used in the routing code? e.g. rt_hash_code() Or is it just trial and error to find a hashing function with a uniform distribution? (I dont believe it is!) Also, why is the source address a part of the hashing function? As far as I can see, in the case of a router, wherever the packet might be coming from (src), its outgoing path would ONLY depend on the destination address and hence the outgoing interface. Regards, Amit -- I'm an angel!!! Honest! The horns are just there to hold the halo up straight. ^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^ Amit Kucheria EECS Grad. Research Assistant University of Kansas @ Lawrence (R): +1-785-830-8521 ||| (C): +1-785-760-2871 ____________________________________________________ - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html _______________________________________________ Linux-cdc mailing list Linux-cdc@kmcdc.wipro.com http://kmcdc.wipro.com/mailman/listinfo/linux-cdc
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