On May 27, 2024, at 09:59, Susanne Will <will.susanne@net-24.at> wrote:

Hi,

sorry for my late answer. I was very busy last days. Yes, i configured non-broadcast because i don't want to have multicast inside my wireguard links. Is it possibble to have bouth, fast hello intervall and non-broadcast?

Yes - you can specify the hold interval to be 1 second (or any other value) on the neighbor command in “router ospf” mode.

I’m assuming you are explicitly configuring neighbors since you don’t have multicast to dynamically discover them.

neighbor A.B.C.D [poll-interval (1-65535)] [priority (0-255)]

Configures OSPF neighbors for non-broadcast multi-access (NBMA) networks and point-to-multipoint non-broadcast networks. The poll-interval specifies the rate for sending hello packets to neighbors that are not active. When the configured neighbor is discovered, hello packets will be sent at the rate of the hello-interval. The default poll-interval is 60 seconds. The priority is used to for the Designated Router (DR) election on non-broadcast multi-access networks.

Hope this helps,

Acee

Here are the requestet outputs of ip ospf interface and tcpdump.

output of "show ip ospf interface" when connection is up

wg1 is up
ifindex 9, MTU 1420 bytes, BW 0 Mbit <UP,POINTOPOINT,RUNNING,NOARP>
Internet Address 10.36.101.1/30, Broadcast 10.36.101.3, Area 0.0.0.0
MTU mismatch detection: enabled
Router ID 10.36.5.1, Network Type NBMA, Cost: 10
Transmit Delay is 1 sec, State Backup, Priority 1
Designated Router (ID) 10.36.100.1 Interface Address 10.36.101.2/30
Backup Designated Router (ID) 10.36.5.1, Interface Address 10.36.101.1
Saved Network-LSA sequence number 0x80000005
Multicast group memberships: OSPFAllRouters
Timer intervals configured, Hello 1s, Dead 5s, Wait 5s, Retransmit 5
    Hello due in 0.012s
Neighbor Count is 1, Adjacent neighbor count is 1
============================================================================================

output of "show ip ospf interface" when connection is down

wg1 is up
ifindex 9, MTU 1420 bytes, BW 0 Mbit <UP,POINTOPOINT,RUNNING,NOARP>
Internet Address 10.36.101.1/30, Broadcast 10.36.101.3, Area 0.0.0.0
MTU mismatch detection: enabled
Router ID 10.36.5.1, Network Type NBMA, Cost: 10
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 10.36.5.1 Interface Address 10.36.101.1/30
No backup designated router on this network
Saved Network-LSA sequence number 0x80000006
Multicast group memberships: OSPFAllRouters
Timer intervals configured, Hello 1s, Dead 5s, Wait 5s, Retransmit 5
    Hello due in 0.327s
Neighbor Count is 0, Adjacent neighbor count is 0
===================================================================================

output of tcpdump when connection is up:

11:31:11.804925 IP (tos 0xc0, ttl 1, id 56965, offset 0, flags [none], proto OSPF (89), length 68)
    10.36.101.2 > 10.36.101.1: OSPFv2, Hello, length 48
   Router-ID 10.36.100.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.2, Backup Designated Router 10.36.101.1
      Neighbor List:
        10.36.5.1
11:31:11.950761 IP (tos 0xc0, ttl 1, id 28025, offset 0, flags [none], proto OSPF (89), length 68)
    10.36.101.1 > 10.36.101.2: OSPFv2, Hello, length 48
   Router-ID 10.36.5.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.2, Backup Designated Router 10.36.101.1
      Neighbor List:
        10.36.100.1
11:31:12.805336 IP (tos 0xc0, ttl 1, id 56968, offset 0, flags [none], proto OSPF (89), length 68)
    10.36.101.2 > 10.36.101.1: OSPFv2, Hello, length 48
   Router-ID 10.36.100.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.2, Backup Designated Router 10.36.101.1
      Neighbor List:
        10.36.5.1
11:31:12.951058 IP (tos 0xc0, ttl 1, id 28026, offset 0, flags [none], proto OSPF (89), length 68)
    10.36.101.1 > 10.36.101.2: OSPFv2, Hello, length 48
   Router-ID 10.36.5.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.2, Backup Designated Router 10.36.101.1
      Neighbor List:
        10.36.100.1
=======================================================================================

output of tcpdump when connection is down:

11:27:18.746172 IP (tos 0xc0, ttl 1, id 27984, offset 0, flags [none], proto OSPF (89), length 64)
    10.36.101.1 > 10.36.101.2: OSPFv2, Hello, length 44
   Router-ID 10.36.5.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.1
11:28:18.746556 IP (tos 0xc0, ttl 1, id 27985, offset 0, flags [none], proto OSPF (89), length 64)
    10.36.101.1 > 10.36.101.2: OSPFv2, Hello, length 44
   Router-ID 10.36.5.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.1
11:29:18.747514 IP (tos 0xc0, ttl 1, id 27986, offset 0, flags [none], proto OSPF (89), length 64)
    10.36.101.1 > 10.36.101.2: OSPFv2, Hello, length 44
   Router-ID 10.36.5.1, Backbone Area, Authentication Type: none (0)
   Options [External]
      Hello Timer 1s, Dead Timer 5s, Mask 255.255.255.252, Priority 1
      Designated Router 10.36.101.1

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