Community discussions

MikroTik App
 
connectlife
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 99
Joined: Tue Sep 01, 2020 10:20 pm

OSPFv3 PTP with multiple routers on the same interface

Wed Mar 02, 2022 6:40 pm

Hello everyone, do you understand that with OSPFv3 an interface configured as PTP only connects to an adjacent device?

With OSPFv2 if for example I configure the vlan850 as PTP and this vlan is configured on 4 routers, in the neighbors I see the routerID and the routes of all 4 routers

With OSPFv3 it doesn't happen, do I have to configure a vlan for each single PTP?

Example: vlan10 Router 1 to Router 2
vlan 11: Router 1 to Router 3
vlan12: Router 1 to Router 4

is it correct or am I wrong something?
 
eduplant
Member Candidate
Member Candidate
Posts: 139
Joined: Tue Dec 19, 2017 9:45 am

Re: OSPFv3 PTP with multiple routers on the same interface

Sat Mar 05, 2022 11:29 am

To confirm: it sounds like you’re saying that using OSPFv2, you run a single broadcast segment where one router is configured as “point-to-point” and the other 4 routers on this same broadcast segment are configured as “point-to-point”? Typically I would think in this case you would use “point-to-multipoint” if you don’t care about the reachability of VLAN 850 itself or “broadcast” if you do. Is there a reason “point-to-multipoint” wouldn’t be suitable for your use case with OSPFv3?

I honestly haven’t tested how RouterOS OSPFv2 behaves if you have 5 routers all configurable as “point-to-point” and all on a broadcast medium, but now you have me curious…
 
connectlife
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 99
Joined: Tue Sep 01, 2020 10:20 pm

Re: OSPFv3 PTP with multiple routers on the same interface

Sat Mar 05, 2022 2:16 pm

Hi, yes we currently have 5 routers in OSPF2 all configured in Point Point .. I have not tried the multipoint point but with the PTP it currently works. The routers see each other correctly and the routes are exchanged .. We use 2 vlan as the routers connect to 2 switches, on one switch we pass the vlan850, on the second the vlan851 (dedicated only to the OSPF area)

On OSPF> Network we set vlan850 in PTP and automatically on Neighbors the routers configured in the same way on the same VLAN appear. Same goes for VLAN851 ..

OSPFv3 uses linklocal if I don't get it wrong ... I'll try Point to Multi Point to see if it works
 
eduplant
Member Candidate
Member Candidate
Posts: 139
Joined: Tue Dec 19, 2017 9:45 am

Re: OSPFv3 PTP with multiple routers on the same interface

Sun Mar 06, 2022 3:08 am

I stood up 3 RouterOSv6.49.2 CHRs on a LAN, configured an extremely basic OSPFv2 configuration, and let it go. In my case, no adjacency successfully forms and all three routers cycle through adjacencies with two other peers. Presumably this is because the whole conversation happens with the multicast address and every packet with a different router ID or different set of parameters confuses it and it tears the adjacency down and starts again:
00:58:27 route,ospf,info Database Description packet has init bit set in middle of an exchange
00:58:27 route,ospf,info OSPFv2 neighbor 10.0.0.3: state change from Full to 2-Way
00:58:27 route,ospf,info OSPFv2 neighbor 10.0.0.3: state change from 2-Way to Down
00:58:27 route,ospf,info OSPFv2 neighbor 10.0.0.2: state change from Exchange to Down
00:58:27 route,ospf,info Discarding packet: no neighbor with this source address
00:58:27 route,ospf,info     RouterId=10.0.0.2
00:58:27 route,ospf,info     source=10.0.0.2
00:58:27 route,ospf,info Discarding packet: no neighbor with this source address
00:58:27 route,ospf,info     RouterId=10.0.0.2
00:58:27 route,ospf,info     source=10.0.0.2
00:58:27 route,ospf,info Discarding packet: no neighbor with this source address
00:58:27 route,ospf,info     RouterId=10.0.0.2
00:58:27 route,ospf,info     source=10.0.0.2
00:58:27 route,ospf,info OSPFv2 neighbor 10.0.0.3: state change from Full to Down
00:58:27 route,ospf,info Database Description packet has init bit set in middle of an exchange
00:58:27 route,ospf,info OSPFv2 neighbor 10.0.0.2: state change from Full to 2-Way
Could you post your OSPF configs so we can get to the bottom of what's happening here?

Who is online

Users browsing this forum: clambert and 18 guests