Here is from rfc4291: 2.6.1. Required Anycast Address
The Subnet-Router anycast address is predefined. Its format is as follows: Hinden Standards Track [Page 12] RFC 4291 IPv6 Addressing Architecture February 2006 | n bits | 128-n bits | +------------------------------------------------+----------------+ | subnet prefix | 00000000000000 | +------------------------------------------------+----------------+ The "subnet prefix" in an anycast address is the prefix that identifies a specific link. This anycast address is syntactically the same as a unicast address for an interface on the link with the interface identifier set to zero. Packets sent to the Subnet-Router anycast address will be delivered to one router on the subnet. All routers are required to support the Subnet-Router anycast addresses for the subnets to which they have interfaces. The Subnet-Router anycast address is intended to be used for applications where a node needs to communicate with any one of the set of routers. So the statements above is what you refer to? The "subnet prefix" in an anycast address is the prefix that identifies a specific link. This anycast address is syntactically the same as a unicast address for an interface on the link with the interface identifier set to zero. Then how does that calculate/126? It should give me four addresses with first one being network ID/anycast address and I could use rest of three, right? honestly, it doesn't sound right to me: So, we subnet the address fec0::/126 according the rules of IPv4; 0~3, 4~7, 8~11, 12~15, and so on... fec0::14/126 is not the first address of that subnet. Or am I missing something? Dave ----- Original Message ---- From: Mark Kamichoff <[EMAIL PROTECTED]> To: a. r.isnaini. rangkayo sutan <[EMAIL PROTECTED]> Cc: snort bsd <[EMAIL PROTECTED]>; juniper-nsp <juniper-nsp@puck.nether.net> Sent: Saturday, 2 February, 2008 12:42:52 PM Subject: Re: [j-nsp] IPv6 subnetting On Fri, Feb 01, 2008 at 01:32:49PM +0700, a. r.isnaini. rangkayo sutan wrote: > Yes, you cannot assign 10::14/126 which 4 I believe is network ID for > /126 (/30 in ipv4), before 10::14/126 there should 10::/126. The first address in any IPv6 subnet is reserved for subnet-router anycast. Section 2.6.1 of RFC 2373 defines this. This also includes the first address of /127's. Reading RFC 3627 (Use of /127 Prefix Length Between Routers Considered Harmful) is probably worthwhile. - Mark -- Mark Kamichoff [EMAIL PROTECTED] http://prolixium.com/ Rensselaer Polytechnic Institute, Class of 2004 Get the name you always wanted with the new y7mail email address. www.yahoo7.com.au/y7mail _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp