On Tue, 07 Mar 2017 18:27:06 -0500, Dennis Bohn said: > AFAICT, Cisco V6 HSRP (mentioning that brand only because it caused me to > try to figure something out, a coincidence that this is in reply to Jakob > from Cisco but is based on what he wrote) relies on Link Local addresses. > I didn't understand why link locals should be there in the first place > seemed klugey and have googled, looked at rfcs and tried to understand why > link local addresses were baked into V6. The only thing I found was that it > enabled interfaces on point to point links to be unaddressed in V6. (To > save address space!??) Can anyone point me in a direction to understand the > reasoning for link local addressing?
Because there are a lot of corner cases where you may want to talk to the network before you find out what your network address is. And if it's a stand-alone network, it may not *have* a well-define network prefix to use for SLAAC auto-config addressing. Think about all the places in IPv4 where you toss packets on the net with your MAC address or a bogus placeholder IP address because you don't have an IP address yet (ARP, DHCP for starters). Link-Local is basically the same thing in the IPv6 world.
pgpXi70hICXMR.pgp
Description: PGP signature
