[AusNOG] FW: [Ap-ipv6tf] official shutdown date for IPv4. The date he is pushing for is April 4, 2024. "IPv4 can't go on forever, " Latour said. "

[Jonathan Thorpe]

Hi Jeremy,

I was under the impression that the routes were being advertised to the upstream, not the clients. I'd misunderstood - thanks for clearing that up.

This works fine if all you want to achieve is redundancy. But what about PBR to distribute different types of traffic across your uplinks? It seems dangerous to try and have your clients doing this when routing should be a function of a router rather than a client.

I accept this only really applies to networks that aren't quite big enough to warrant advertising their own address space (generally not the audience of AusNog), but having this work quite nicely in IPv4 and having spent considerable time in recent months considering how this might be done in IPv6, I've come to warm to NPTv6.

Kind regards,
Jonathan

-----Original Message-----
From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Jeremy Visser
Sent: Thursday, 6 November 2014 1:04 PM
To: ausnog at lists.ausnog.net
Subject: Re: [AusNOG] FW: [Ap-ipv6tf] official shutdown date for IPv4. The date he is pushing for is April 4, 2024. "IPv4 can't go on forever, " Latour said. "

On 06/11/14 12:43, Jonathan Thorpe wrote:
> In practice, devices that can manage failover for small sites over a 
> couple of business grade DSL Services from diverse providers have a 
> low barrier of entry (achievable for around $100 and easy to set up) 
> and can in some cases be scaled to support device level redundancy 
> (pfSync etc).
> 
> In IPv6, the premise that sites should advertise address space 
> upstream to achieve this makes it all but impossible because: * Sites 
> need to now get an ASN, pay for and manage their own public address 
> space.

I think you misread Mike in the above.  Nothing he suggested implied that getting advertising a prefix assignment upstream or getting an ASN.

What he was suggesting was running two routers in parallel (or one router with two upstreams) and advertising separate prefixes (i.e. dual Router Advertisements) which causes each device to get two sets of global addresses.

These routers don't even need to be aware of each other.  They should just sit on the same Layer 2 broadcast domain firing off Router Advertisement packets.

As Mike said:

> IPv6 based failover you simply advertise both prefixes and the client 
> can chose which source address to use
> 
> For IPv6 you simply have both routers plugged in at the same time, if 
> one goes down it stops advertising itself and clients stop using it.

When one router's WAN goes down, it will send out an RA packet notifying that the prefix is deprecated, and clients will stop using those addresses.

Obviously a larger institution will want to get their own /48 allocation and an ASN, but it is possible to do it on the cheap too.
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