Re: [Cbor] changes in draft-ietf-cbor-network-addresses-05.txt

[Brian E Carpenter <[e-mail]>]

> For the Interface form, adding a third (optional) field for scope is easy.
> I am open to suggestions for handling the Address format.

It gets a bit messy. If you transmit the zone id as a string, you
could use [address, 'eth0'] which would be distinguishable from the
other cases.

By the way, I love the thought of interface -15. RFC4007 is looking
a bit sickly to me.

Regards
   Brian

On 02-Aug-21 10:21, Michael Richardson wrote:
> 
> Brian E Carpenter <[e-mail]> wrote:
>     > On 01-Aug-21 23:30, Jürgen Schönwälder wrote:
>     >> The description statements in RFC 6991 talk about a zone index, i.e.,
>     >> they assume the zone index is numeric (which kind of follows from my
>     >> reading of RFC 4007).
>     >>
>     >> The pattern is flexible enough to accept a string as well (e.g., 
an
>     >> interface name). In other words, a server may accept 'fe80::1%lo0' as
>     >> valid input on an edit-config put it will return 'fe80::1%0' on a
>     >> get-config since the numeric zone index is the canonical format
>     >> (assuming the lo0 interface has the interface index 0).
> 
>     > This still makes me uncomfortable. The zone identifier syntax definition.
>     > in RFC4007 is pretty vague. If an implementer chooses to ignore the
>     > SHOULD on page 16, it seems that a valid name for interface index 
7
>     > could be "6". That's why "canonical" is a bit weak. (Neither Windows
>     > nor Linux allow anything that silly, of course.)
> 
> Is this what you mean... picking on an interface I'm not using today:
> 
> %ip link ls dev virbr0
> 15: virbr0: <BROADCAST,MULTICAST> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
>     link/ether 52:54:00:14:c7:73 brd ff:ff:ff:ff:ff:ff
> %sudo ip link set name "15" dev virbr0
> %ip link ls dev virbr0
> Device "virbr0" does not exist.
> 
> %ip link ls dev 15
> 15: 15: <BROADCAST,MULTICAST> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
>     link/ether 52:54:00:14:c7:73 brd ff:ff:ff:ff:ff:ff
> 
>     > An implementation SHOULD support at least numerical indices that are
>     > non-negative decimal integers as <zone_id>.
> 
> Oh.
> 
> %sudo ip link set name "-15" dev "15"
> %ip link ls dev -15
> 15: -15: <BROADCAST,MULTICAST> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
>     link/ether 52:54:00:14:c7:73 brd ff:ff:ff:ff:ff:ff
> 
>     > An implementation MAY support other kinds of non-null strings as
>     > <zone_id>.
>     > ... the format MUST be used only within a
>     > node and MUST NOT be sent on the wire unless every node that
>     > interprets the format agrees on the semantics.
> 
> :-)
> 
>     > Remotely, there is no way to know that on my Linux machine,
>     > %wlp2s0 and %3 are the same thing.
> 
> Agreed.
> But, SNMP and YANG know.
> So if you are doing CORECONF, then you might want to encode stuff.
> 
> And if you want to set an IPv6-LL address for a daemon to listen on, then you
> need the scope.  That seems to be the place where we need this, and this
> would seem to be the use case.
> 
> (Looking back at my code involving IPsec configuration over LLv6, I see 
that
> actually, I am in trouble if v6LL addresses are ever duplicated, as I don't
> send the scope)
> 
> For the Interface form, adding a third (optional) field for scope is easy.
> I am open to suggestions for handling the Address format.
> 
> --
> Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
>            Sandelman Software Works Inc, Ottawa and Worldwide
> 
> 
> 
>