Router ID on IPv6-Only
cjc+nanog at pumpky.net
Fri Sep 9 06:27:01 UTC 2022
As I said in the original email, I realize router IDs just need to be
an AS. We could have done random ones with IPv4, but using a well chosen
address assigned to the router guarantees uniqueness as well as some
properties. I was wondering if people had some ways to do something
But I think the most notable thing from the handful of responses (and
all that responded) was that no one piped up who is actually doing it. I
most everything is still dual-stack.
And to get even a little more specific about our particular use case and
suggestion here to build the device location into the ID, we're
really talking about one ID per physical router here. I'm really talking
IPv6-only VRFs. The router (L3 switch, firewall, or whatever it may be)
have a mix of IPv6-only, IPv4-only, and dual-stack VRFs. I think
per device is no longer exotic configuration and closer to the norm.
And before anyone suggests borrowing IPv4 addresses from other VRFs to
the IPv6-only VRFs, that was something we discounted right away for what
are pretty obvious reasons.
On 2022-09-08 08:28, J. Hellenthal wrote:
> Personally it just needs to be unique. Relying on a Id to be unique
> when ascociated to an IP address that may be used on a failover system
> seems really poor to me.
> Assign a random ID and plug it into your IPAM!. If at anything assign
> a router ID to a rack location and associate every bit of information
> about that location in whatever you're tracking management can
> Personally I prefer date originated generated numbers that allow me to
> filter upon such and spill out the results to tell me where its at
> what rack its in, slot number etc...
> But then again this is from a failover system perspective...
>> On Sep 8, 2022, at 10:13, Randy Bush <randy at psg.com> wrote:
>>> During some IPv6 numbering discussions at work today, someone had a
>>> question that I hadn't really considered before. How to choose 32-bit
>>> router IDs for IPv6-only routers.
>> arbitrary 32 bit number unique in the autonomous system. even in an
>> ipv4 world it does not need to match any configured interface address.
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