[j-nsp] Collapse spine EVPN type 5 routes issue

[niklas rehnberg]

Hi all,
I have the following setup and need to know the best practices to solve
EVPN type 5 issues.

Setup:
Two ACX7100 as collapse spine with EVPN/VXLAN
Using type 5 routes between the spines so iBGP can be avoided in
routing-instance.
Both spines has same bgp as number in the routing-instance WAN
See below for a part of configuration

Problem:
Incoming routes from WAN router into spine1 will be advertised to spine2 as
type 5 routes
spine2 will not accept them due to AS number exit in the as-path already.

Solution:
I can easily fix it with "loop 2" config in the routing-options part, but
is this the right way?
Does there exist any command to change the EVPN Type 5 behavior from eBGP
to iBGP?
Different AS number in routing-instance?
What are the best practices?

Config part:
show routing-instances WAN protocols evpn
ip-prefix-routes {
    advertise direct-nexthop;
    encapsulation vxlan;
    reject-asymmetric-vni;
    vni 99100;
    export EXPORT-T5-WAN;
}
policy-statement EXPORT-T5-WAN {
    term 1 {
        from protocol direct;
        then accept;
    }
    term 2 {
        from protocol bgp;
        then accept;
    }
}