Re: Why specify a default router?
On Tue, Jul 05, 2005 at 12:07:53AM -0700, The Orange Rider wrote:
> Time and time again I read about how hosts don't need to have a
> default gateway configured statically in IPv6 as they did in IPv4
> becuase they will automatically discover the router via Neighbor
> Discovery Protocol (through Router Solicitations and Router
> Advertisments and all that).
Router Advertisement and Router Discovery is ICMPv6.
> This is all well and good, except that Linux still supports the manual
> configuration of a router (route add -inet6 [ipv6_address]). What I
> don't understand is why this is supported at all. Since IPv6 lacks ARP
> requests, it seems as though a host would still have to resolve the
> router via NDP even if it is manually configured with a default
> router.
Neighbour Discovery is not much different from ARP. You resolve inet6
addresses into MAC Addresses. It is done with icmp6 messaes to multicast
instead of arp broadcasts. But you can use it the same way to map the inet6
address of a router to its medium address.
If you dont run route advertisement or if you specify the gateway address by
dhcp the static gateway is needed. There is not really a difference between
ipv4 and ipv6.
Gruss
Bernd
Reply to: