Messages in this thread | | | Date | Wed, 9 Oct 2002 18:11:11 +0100 | From | Derek Fawcus <> | Subject | Re: [PATCH] IPv6: Fix Prefix Length of Link-local Addresses |
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On Thu, Oct 10, 2002 at 01:54:32AM +0900, YOSHIFUJI Hideaki / ?$B5HF#1QL@?(B wrote: > In article <20021009170018.H29133@edinburgh.cisco.com> (at Wed, 9 Oct 2002 17:00:18 +0100), Derek Fawcus <dfawcus@cisco.com> says: > > > All link local's are currently supposed to have those top bits > > ('tween 10 and 64) zero'd, however any address within the link local > > prefix _is_ on link / connected and should go to the interface. > > > > i.e. it's perfectly valid for me to assign a link local of fe80:1910::10 > > to an interface and expect it to be work, likewise for a packet > > destined to any link local address to trigger ND. > > First of all, please don't use such addresses.
Why not, they are perfectly legal?
> By spec, auto-configured link-local address is fe80::/64 > and connected route should be /64.
Yes auto-configured have fe80:0:0:0: in their upper 64 bits, but that is just for autoconfigured addessses. That is a seperate issue to which prefix desinates link local.
Connected routes don't have to be /64, things work correctly even if one picks any other value.
> If you do really want to use such addresses (like fe80:1920::10), > you can put another route by yourself, at your own risk.
No - what I'm saying is that all link locals should go to the link.
There is no risk inherent in using such an address or link local prefix.
If a mechanism is required such that autoconfig generates the correct type of address, then add it. But that doesn't _require_ that the connected route be /64.
I happen to use link locals like the quite often, since it makes testing and reading packet traces a hell of a lot easier.
> We should not configure in such way by default. > and, we should even have to add "discard" route for them > by default for safe.
Why. In what way is it not 'safe' to have any link local address sent onto the link? They'll either reach a destination or not, but given that they'll never leave the link, they can't be inherently unsafe.
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