What is the best practice? Configuring a static link-local address on the interface, or letting the router pick an eui-64 one?
From a dynamic routing process point of view, does it really matter which type of link local address is used in a production network?
I know that static addresses are more convinient for humans. But what about the IOS?
Any other considerations?
Thank you all.
I would say that as you already know when you use a routing protocol on IPv6 the neighbor will always be the link local address from the interface from the neighbor itself,
So I would say why to use Dynamic( Cause it's easy,it's scalable as it's based on a unique value)
Why to use Static ( So you can create your own system to identify the neighbor, I have read that for security purposes you can use a mechanism that will create random EUI-64 based on a hash but as this is only for Link-Local address I would say it does not apply here)
Ideal world - use standard M-EUI-64 for link-local addresses and then use a FHRP like HSRP for the static address. That way your routers are all dynamic, but the address humans use for the default gateway can be something like fe80::VLAN#:1 or whatever makes sense for you. That said, I would try to stick with using RAs for your default gateway. The only exceptions should be infrastructure devices that either don't run or aren't configured with a routing protocol such as load balancers and firewalls.