Thanks everyone for your input! I now have a more complete perspective on the pros and cons of the options available. -Daniel Le 26/01/2012 09:18, Mohacsi Janos a écrit :
On Wed, 25 Jan 2012, Daniel STICKNEY wrote:
I'm having trouble finding authoritative sources on the best common practice (if there even is one) for the choice of address for an IPv6 default gateway in a production server environment (not desktops). For example in IPv4 it is common to chose the first or last address in the subnet (.1 or .254 for example) as the VIP for VRRP/HSRP. I'm interested in input from production environments and or ARIN/RIPE/IANA/etc or top vendors.
I've seen some documentation using <prefix>::1 with either a global prefix or link-local (fe80::1). Anyone use either of these in production and have negative or positive feedback? fe80::1 is seductive because it is short and the idea of having the same default gateway configured everywhere might be simple. At the same time using the same address all around the network seems to invite confusion or problems if two interfaces with the address ever ended up in the same broadcast domain.
Up to your taste. Most cases it is recommended to use link-local default gateway. If you use the same address - even link local - your node should complain about the duplicate address on the same link. You can rely on the autoconfigured link-local address for default gateways (and use RA).
What about using RAs to install the default route on the servers? The 'priority' option (high/medium/low) easy fits with an architecture using an active/standby router setup where the active router is configured with the 'high' priority and the standby 'medium'. With the timeout values tuned for relatively rapid (~3 seconds) failover this might be feasible. Anyone use this in production?
Yes we are using NUD (and using RA to install default gateway) to switch from primary rotuer to secondary - due to no VRRP support on a particular platform. But in case of RA usage you should also use RA-guard especially if you don't have full control on servers connected to your switches.
I note that VRRPv3 (and keepalived) and HSRP both support IPv6. Since we use VRRP for IPv4, using it for IPv6 would keep our architecture the same, which has merit too.
If you want consistent and more predictable behavoir use VRRP or maybe HSRP if your vendor supports it. Best Regards, Janos Mohacsi