Add network instance name on interface, IPv4, IPv6

[Qin Wu <[e-mail]>]

Hi, authors:

In RFC8529, the bind-network-instance-name leaf provides the association between an interface and its associated NI.

However it is not clear to me why the same association between Ipv4/Ipv6 type and its association NI

Should be provided as well? See model structure snippet defined in RFC8529 as follows:
"
   augment /if:interfaces/if:interface:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name
   augment /if:interfaces/if:interface/ip:ipv4:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name
   augment /if:interfaces/if:interface/ip:ipv6:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name
"

So the question is

Can we add different NI name for IPv4/IPv6 type? Isn't IPv4 type and IPv6 type and interface pointing to the same NI name?

Why IPv4 type and IPv6 type in IP data model can not inherit the same NI name from the interface model since IP Data model is an extension to Interface Data Model?
Suppose we configure interface and associated IP addresses and assign this interface to a NI,
Which configuration snippet is correct:
Option A:
{
"name": "eth1",
"type": "iana-if-type:ethernetCsmacd",
"ietf-ip:ipv4": {
"address": [
{
"ip": "192.0.2.11",
"prefix-length": 24
}
]
"ietf-network-instance:bind-network-instance-name": "vrf-red"
},
"ietf-ip:ipv6": {
"address": [
{
"ip": "2001:db8:0:2::11",
"prefix-length": 64
}
]
"ietf-network-instance:bind-network-instance-name": "vrf-red"
},
"ietf-network-instance:bind-network-instance-name": "vrf-red"
},
Option B:
{
"name": "eth1",
"type": "iana-if-type:ethernetCsmacd",
"ietf-ip:ipv4": {
"address": [
{
"ip": "192.0.2.11",
"prefix-length": 24
}
]
},
"ietf-ip:ipv6": {
"address": [
{
"ip": "2001:db8:0:2::11",
"prefix-length": 64
}
]
},
"ietf-network-instance:bind-network-instance-name": "vrf-red"
},

-Qin