Re: Routing between hosts in ULA subnets

Andres,

Thanks for writing up this use-case.  Quick Q - What global ID would get
used in the ULA (assuming GUA is not known yet)?

> In a homenet case, why cannot the default ULA policy be boiled down to
>"Discard 
> ULA packets trying to pass the CER"?

That would be reasonable. Perhaps, just deny forwarding any traffic over
an interface that doesn't have any ULA assigned.

Cheers,
Rajiv

-----Original Message-----
From: Anders Brandt <Anders_Brandt@sigmadesigns.com>
Date: Thu, 22 Mar 2012 10:00:56 +0000
To: 6man <ipv6@ietf.org>, Tim Chown <tjc@ecs.soton.ac.uk>, Don Sturek
<d.sturek@att.net>, "homenet@ietf.org Group" <homenet@ietf.org>, Ray
Hunter <v6ops@globis.net>, Brian E Carpenter
<brian.e.carpenter@gmail.com>, Thomas Herbst <therbst@silverspringnet.com>
Subject: Routing between hosts in ULA subnets

>As a branch of the discussion [homenet] ULA scope
>[draft-ietf-6man-rfc3484-revise-05.txt],
>I would like some clear explanation of the actual issues related to
>routing between hosts in ULA subnets.
>Some people seems to be concerned for a reason that seems pretty unclear
>to me.
> 
>Here is my use case:
>=================
> 
>I have a new house. The electrician installs lighting devices from two
>vendors using different LLN technologies,
>e.g. power line and RF.
>The ISP has not installed a CER router yet, so there is no central source
>of prefixes or naming service.
> 
>The electrician completes his installation by including devices with
>their respective border routers and testing
>
>with a stand-alone tool that all devices communicate correctly.
> 
>Now a technician sets up advanced rules for how timers and sensors
>control lights and window blinds.
>He plugs a cable between the two LLN border routers and connects a PC.
>He uses mDNS to discover the devices via Resource Directories in the LLN
>border routers.
>Devices are configured to control other devices using some application
>protocol.
>Everything works when the technician leaves the house.
> 
>A week later the ISP installs the CER router. Everything still works.
> 
> 
>Here is my question(s):
>==================
> 
>Why should homenet require the subnet ULAs to be distributed from another
>router?
>
>It works without extra routers in the scenario described above.
>
>(Actually, the technician's configuration would break if new ULAs were
>distributed by another router later on).
> 
>Why cannot two border routers connected to the homenet LAN make routing
>protocol announcements
>
>for two different ULA prefixes - such as:
>"I am the router with LAN link-local address X and you can use me to
>reach ULA subnet XX"  ?
> 
>In a homenet case, why cannot the default ULA policy be boiled down to
>"Discard ULA packets trying to pass the CER"?
> 
> 
>Thanks,
>  Anders
> 
> 
>
>
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