Several IPv6 routers and default gateway choice

[Victor Sudakov]

Hiroki Sato wrote:
> va> > va> Can any IPv6 unicast or link-local address be configured as an anycast
> va> > va> address of a router?
> va> >
> va> >  Yes.  There is no restriction about address scope.
> va> >
> va> >  You might want to read RFC 4291, which defines Subnet-Router anycast
> va> >  address, and RFC 2526, which defines the other reserved IPv6 subnet
> va> >  anycast addresses.  In general, the former one can be used for
> va> >  routing purpose.
> va>
> va> Interestingly, RFC4291 says that "All routers are required to support
> va> the Subnet-Router anycast addresses for the subnets to which they have
> va> interfaces." In practice, I don't observe this. A FreeBSD router does
> va> not configure such an address automatically, for example.
> 
>  They will be automatically configured when an ipv6_prefix_IF
>  rc.conf(5) variable is used to configure a prefix:
> 
> ----(from rc.conf(5) man page)----
>  ipv6_prefix_ed0="2001:db8:1:0 2001:db8:2:0"
> 
>  is equivalent to the following:
> 
>  ifconfig_ed0_alias0="inet6 2001:db8:1:: eui64 prefixlen 64"
>  ifconfig_ed0_alias1="inet6 2001:db8:1:: prefixlen 64 anycast"
>  ifconfig_ed0_alias2="inet6 2001:db8:2:: eui64 prefixlen 64"
>  ifconfig_ed0_alias3="inet6 2001:db8:2:: prefixlen 64 anycast"
> 
>  These Subnet-Router anycast addresses will be added only when
>  ipv6_gateway_enable is YES.
> ----------------------------------

Dear Hiroki,

You are an invaluable source of information. I wish all the above should
make it into the Handbook, the chapter on IPv6.



-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
2:5005/49 at fidonet http://vas.tomsk.ru/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 455 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-net/attachments/20190912/1ac998c5/attachment.sig>