Ted Lemon (Apple): There are good reasons both for wanting to use the
ULA prefix and for wanting to use the GUA prefix
For unconstrained networks we can simply take all available prefixes
For constrained networks the SNAC router may need to pick. Generally we
may assume that the GUA prefix is more stable, and the GUA also allows
global connectivity. All SNAC routers on a mesh need to make the same
decision.
Esko Dijk: Sounds good.
Éric Vyncke (Cisco): Why not select one ULA plus one GUA? Because their
properties are different and useful.
Ted Lemon (Apple): It may not always be true that all routers on a mesh
get allocated the same GUA prefixes.
There may not be a solution that is perfect in every scenario.
Éric Vyncke (Cisco): If multiple CE routers allocating /64 from their
/48, should the multiple SNAC routers select from the same CE router (to
allow easier communication). Éric suggest sorting the ULA/GUA delegated
prefixes and selecting the smaller or higher.
Timothy Winters (QA Cafe): LAN Prefix Delegation Requirement LPD-9 in
IPv6 CE Routers LAN Prefix Delegation recommends that “If the CE
Router is provisioning both ULA and GUA via prefix delegation, the GUA
SHOULD appear first in the packet.”
Basic Requirements for IPv6 Customer Edge Routers
https://datatracker.ietf.org/doc/html/draft-ietf-v6ops-rfc7084bis
Ted Lemon (Apple): The SNAC routers are not the constrained devices
here. The nodes on the mesh may generally be constrained devices.
Ted Lemon (Apple): Three points [...]
Esko Dijk: Behavior can be different for different stub network
technologies.
Christian Amsüss: This should be a per-host choice.
Matthias Kovatsch (Siemens): Summarized constrained case as machine to
machine automation apps. Local function is important even if internet
connection goes away. In favor of two prefixes ULA - to keep local
network stable, and GUA - for all other cases. Esko notes hosts may have
only space for one prefix... Matthias says get both and let the host
choose.
Masanobu Kawashima (NEC Platforms, Ltd.): It is hard to choose between
ULA and GUA. Why not use RFC 6724 Default Address Selection? If you
don't like it you can change your policy by changing configuration.
Ted Lemon (Apple): Maybe we can say that the default is to distribute
the ULA to every device, and devices that also need a GUA can request
one through other means.
On the other hand, we could just decide to use the extra bytes in the
messages (around 8 bytes, or a little more) and offer one ULA and one
GUA to every device.
(To Tim Winters): What does your document recommend?
Timothy Winters (QA Cafe): Devices should support both, with the GUA
option first. We have observed no current home routers that offer ULA
addresses.
Ted Lemon (Apple): RFC 7084
Matthias Kovatsch (Siemens): Use ULAs provisioned via slaac, if one
border router goes away there is disruption until the devices stabalize.
PD with ULA might be a way to get automation deployments more stable.
ULA in general a use case for automation networks.
Ted Lemon (Apple): May not want to have IOT devices getting GUA. Maybe
there is a configuration nob needed in the home/CE router or DHCP
server.
Stuart: Remember, this is the Stub Network Auto Configuration working
group. Our job is to decide a sensible default behavior for devices that
are not manually configured. That does not mean that knowledgeable
operators are not allowed to change that default.
Issue 126: From RFC4861 - notes added
Issue 125: Strong SHOULD - notes added
Issue 124: defaults are suggested based on RFC4861 - notes added
Issue 123: Appendices are not normative, note this and the use of
normative language is reflecting the base draft content.
Issue 122: Questions about the appendix a.1... ther are other scenarios
with isolated hosts on a guest network
Issue 120: Clarify RA Guard in Appendix A, clarify with DHCPv6 PD. -
notes updated.
- RA Guard discussion ensued... The conclusion was that it works.
Issue 119: Description of stub router behavior added to issue notes.
Issue 118: Multi-homing discussion, with conclusion
Stuart: Mesh, Mesh+AIL, Mesh+AIL+routed networks, Mesh+AIL+routed
network+global internet41409
Darren: Thanks Timothy Winters for agreeing to be the SNAC Simple
document shepherd
Darren: We will have interim meetings every two weeks to close the
document