Can't get the NHRP/GRE to work

[02Spar]

Hi,

I'm currently trying to mount a DMVPN between a CISCO hub and a FRR spoke, but I encountered some difficulties doing it, so I first tried to apply the example configuration given in the official documentation with two routers directly connected.
In either case, the spoke router doesn't send any IKE messages to the hub router to initiate the tunnel.

I believe that the issue is on my side as other people are getting it to work successfully.

I'm using the following versions:

• OS : Debian 11 (bullseye)
• Kernel : 5.10.0-21-amd64
• FRR : 8.5
• StrongSwan : 5.9.10 + patches given in the frr documentation

Here are my router configurations:

hub-rtr:

Current configuration:
!
frr version 8.5
frr defaults traditional
nhrp nflog-group 1
hostname hub-rtr
service integrated-vtysh-config
!
interface enp0s3
 ip address 192.168.1.254/24
exit
!
interface enp0s8
 ip address 172.16.0.254/24
exit
!
interface gre1
 description DMVPN Tunnel Interface
 ip address 10.0.0.254/32
 ip nhrp network-id 1
 ip nhrp redirect
 ip nhrp registration no-unique
 ip nhrp shortcut
 tunnel protection vici profile dmvpn
 tunnel source enp0s3
exit
!
router bgp 65000
 bgp router-id 10.0.0.254
 no bgp ebgp-requires-policy
 neighbor SPOKES peer-group
 neighbor SPOKES disable-connected-check
 neighbor 10.0.0.1 remote-as 65001
 neighbor 10.0.0.1 peer-group SPOKES
 !
 address-family ipv4 unicast
  network 172.16.0.0/24
  redistribute nhrp
 exit-address-family
exit
!
end

hub-rtr# sh ip nhrp 
Iface    Type     Protocol                 NBMA                     Claimed NBMA             Flags  Identity
gre1     local    10.0.0.254               192.168.1.254            192.168.1.254                   -

spoke-rtr:

`Current configuration:
!
frr version 8.5
frr defaults traditional
hostname spoke-rtr
service integrated-vtysh-config
!
interface enp0s3
 ip address 192.168.1.1/24
exit
!
interface enp0s8
 ip address 172.16.1.254/24
exit
!
interface gre1
 description DMVPN Tunnel Interface
 ip address 10.0.0.1/32
 ip nhrp map 10.0.0.254 192.168.1.254
 ip nhrp map multicast 192.168.1.254
 ip nhrp map multicast dynamic
 ip nhrp network-id 1
 ip nhrp nhs 10.0.0.254 nbma 192.168.1.254
 ip nhrp redirect
 ip nhrp registration no-unique
 ip nhrp shortcut
 tunnel protection vici profile dmvpn
 tunnel source enp0s3
exit

router bgp 65001
 no bgp ebgp-requires-policy
 neighbor 10.0.0.254 remote-as 65000
 neighbor 10.0.0.254 disable-connected-check
 !
 address-family ipv4 unicast
  network 172.16.1.0/24
 exit-address-family
exit
!
end

spoke-rtr# sh ip nhrp 
Iface    Type     Protocol                 NBMA                     Claimed NBMA             Flags  Identity
gre1     local    10.0.0.1                 192.168.1.1              192.168.1.1                     -

I'm using the same parameters as in the official documentation for the dmvpn security profile and the nflog-group.

Interface status - hub-rtr:

8: gre1@enp0s3: <UP,LOWER_UP> mtu 1472 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre 192.168.1.254 brd 0.0.0.0 promiscuity 0 minmtu 68 maxmtu 65507 
    gre remote any local 192.168.1.254 dev enp0s3 ttl inherit addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

Interface status - spoke-rtr:

9: gre1@enp0s3: <UP,LOWER_UP> mtu 1472 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre 192.168.1.1 brd 0.0.0.0 promiscuity 0 minmtu 68 maxmtu 65507 
    gre remote any local 192.168.1.1 dev enp0s3 ttl inherit addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 

I have tried to set the tunnel source outside of frr as stated in #13219, but no more luck on that side.

What am I missing out ?