I've had good luck in a corporate environment using fe80::1 on Cisco 6500/7600 with newer IOS. However, some software routers still won't let you use a link-local as a VIP (at least in HSRP). I'm upgrading one of our 7200 tonight running 15.1(4)M1 to M3, hopefully that will fix it (we are upgrading it for other reasons). For example: int vlan110 standby 110 ipv6 FE80::1 standby 110 timers msec 250 msec 750 standby 110 priority 110 standby 110 preempt delay minimum 180 ---- Matthew Huff | 1 Manhattanville Rd Director of Operations | Purchase, NY 10577 OTA Management LLC | Phone: 914-460-4039 aim: matthewbhuff | Fax: 914-460-4139
-----Original Message----- From: Daniel STICKNEY [mailto:dstickney@optilian.com] Sent: Wednesday, January 25, 2012 9:42 AM To: nanog@nanog.org Subject: Choice of address for IPv6 default gateway
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.
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?
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.
Thanks in advance,
Daniel STICKNEY