IPv6 Link-local addresses: EUI-64 or Static?

[b.kanani]

Hello Everyone.

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.

[Julio Carvajal]

Hello,

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)

Regards

[jsmall123]

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.