Re: [v6ops] I-D Action: draft-ietf-v6ops-conditional-ras-01.txt

[Jen Linkova <[e-mail]>]

Hi Dusan,

On Thu, Mar 22, 2018 at 5:22 AM, Mudric, Dusan (Dusan)
<[e-mail]> wrote:
>> Would you be able to give an example for 'most preferred'? The network
>> has two uplinks to two ISPs, two prefixes. Both uplinks can be used.
>> Each border router has a default route pointing to the uplink.
>> What prefix is 'most preferred' to reach  Internet?

> [[Dusan]] One ISP might be more reliable or can provide better QoS, for example.

In this case it comes down to 'active/backup uplink' scenario: use the
more reliable uplink, keep the second one as a backup/prefix
deprecated.

> [[Dusan]] Why the Prf from rfc4191#section-2.2 cannot be set by the router? This is not a protocol change? The flags are already defined in the RFC4191.

It can be set by a router but I'm aware of just one host OS which
supports this. So the router preference in RAs would not be recognized
by end devices.
Again, please note, that the draft documents a solution which can be
deployed *today* in SMB/Enterprise environment, where BYOD is common,
w/o upgrading/replacing host OSes.

>> > and they should have the preference assigned.
>>
>> Which hosts would not recognize.
>
> [[Dusan]] This is an implementation aspect. If hosts implement the Prf from rfc4191#section-2.2, they will recognize Rrf. You should not limit the options based on the current implementations.

It looks like I'm not explaining it properly.
*This* particular draft is written to document a solution which works
with existing hosts in existing networks today.
Solutions which do not exist right now but may be deployed in 3-5-10
years, when all hosts get new shiny features implemented are out of
scope of this particular document. As I've mentioned, a solution
similar to what you are suggesting (using 5.5 and rfc4191) is
documented in https://tools.ietf.org/html/draft-ietf-rtgwg-enterprise-pa-multihoming
.

> [[Dusan]] I think Rrf setting should be in the draft. It might not be used by the hosts today, but can be used by the hosts of tomorrow.

What would be the difference between what you are suggesting and
draft-ietf-rtgwg-enterprise-pa-multihoming?

-- 
SY, Jen Linkova aka Furry