Dear Zarrar,
With Interface IDs (IIDs) that are 8 bytes in size and MAC addresses that are 6 bytes in size, having overlapping solicited node multicast addresses is inevitable. This doesn't, however, cause any harm. Of the two nodes, only the one with the targeted (solicited) address will respond. For DAD, an NS is sent by the node seeking to use a certain address. The "owner" of the address, if any, must respond. However, for the "owner" to defend the address, it must have it in the preferred or deprecated state and not in the tentative state. I hope this adds some clarity. Regards, Salah ________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, July 06, 2007 3:52 PM To: [email protected] Subject: [mipl] Conceptual issue about DAD Dear All, I have two nodes with the following MAC Addresses MAC Address Node1: 0A:AA:1C:36:48:01 MAC Address Node2: 0B:BB: 1B:36:48:01 Based upon the address autoconf process, the following tentative link-local address will be formed: Tentative Link-local Address Node1: FE80::0AAA:FF1C:FE36:4801 / 64 Tentative Link-local Address Node2: FE80::0BBB: FF1B: FE36:4801 / 64 And the following Solicited Node Multicast addresses Solicited Node Multicast Address 1: FF02::1:FF36:4801/104 Solicited Node Multicast Address 2: FF02::1:FF36:4801/102 >From above it is seen that although the Link-local address formed by the two nodes is different, but they have the same solicited node multicast address. Now, for DAD, when an NS (with unspecified source address and Solicited Node Multicast Address as destination address) is received by node 2 (because of the same solicited node multicast address), the receiving node will know that the target address in duplicate, wherein from the above the Tentative 1 (Carried as Target Address) and tentative 2 are distinct and they are NOT duplicate, but according to RFC 2462 these addresses will be considered duplicate. WHY ? Also Section 5.4.3 para 1 RFC 2462 states that a node MUST NOT respond to a Neighbor Solicitation for a tentative address, whereas i read somewhere that for DAD, if a node does not receive an NA in response to NS within RetransTimer seconds, the address is unique, in other words for DAD an NA is necessary. What am i missing, or what am i doing wrong? Zarrar ________________________________ Local listings, incredible imagery, and driving directions - all in one place! Find it! <http://maps.live.com/?wip=69&FORM=MGAC01>
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