Choice of address for IPv6 default gateway

Wed Jan 25 14:52:36 UTC 2012

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 at optilian.com]
> Sent: Wednesday, January 25, 2012 9:42 AM
> To: nanog at 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
> 