Community discussions

MikroTik App
 
User avatar
IPANetEngineer
Trainer
Trainer
Posts: 1333
Joined: Fri Aug 10, 2012 6:46 am
Location: Jackson, MS, USA
Contact:

Re: Point-to-point (/31) addresses

Wed Feb 04, 2015 7:22 pm

I could go either way on that...it would be nice to have, but given all the development features requested of MikroTik , I'd rather see MPLS fast reroute or BGP ECMP before /31 addresses.
Global - MikroTik Support & Consulting - English | Español | Serbian | Danish +1 855-645-7684
https://iparchitechs.com/ecosystem/mikr ... consulting mikrotiksupport@iparchitechs.com
 
User avatar
nicktc
just joined
Posts: 13
Joined: Mon Mar 28, 2016 9:52 pm
Location: The Netherlands
Contact:

Re: Point-to-point (/31) addresses

Mon Jul 25, 2016 1:09 am

Sorry if I'm reviving a really old thread, however..

Using 10.0.0.A/32 to link router A-B-C together things that work great:
- OSPF
- MPLS
- LDP
- VPLS (point to point between A-B or B-C)

Things that do not work correctly
- VPLS (between A-C no data RX on either router)

Adding an additional loopback address and using it as a transport address seems to "fix" the problem.

This is on 6.36

Anyone else seeing the same issue?
 
asy
newbie
Posts: 40
Joined: Thu Oct 18, 2012 2:26 pm

Re: Point-to-point (/31) addresses

Tue Feb 27, 2018 1:20 pm

Are there any plans to support RFC 3021 in RouterOS now ?
 
JimmyNyholm
Member Candidate
Member Candidate
Posts: 249
Joined: Mon Apr 25, 2016 2:16 am
Location: Sweden

Re: Point-to-point (/31) addresses

Tue Feb 27, 2018 5:46 pm

I would skip using an actual /31, and just use two /32s. Specify the remote address as the "network", and you should be good to go.

This mechanism is more flexible than using /31s, as the addresses don't need to be adjacent; and more efficient since you can re-use the same address for multiple links on a router.

In your particular case:

R1: /ip add add interface=ether1 address=10.10.10.2/32 network=10.10.10.3
R2: /ip add add interface=ether1 address=10.10.10.3/32 network=10.10.10.2

Will do the trick.

In a more complex hypothetical setup, with four routers connected to each other in a full-mesh of point-to-point ethernets:

R1: /ip add add interface=ether1-to-R2 address=10.10.10.1/32 network=10.10.10.2
R1: /ip add add interface=ether2-to-R3 address=10.10.10.1/32 network=10.10.10.3
R1: /ip add add interface=ether3-to-R4 address=10.10.10.1/32 network=10.10.10.4

R2: /ip add add interface=ether1-to-R1 address=10.10.10.2/32 network=10.10.10.1
R2: /ip add add interface=ether2-to-R3 address=10.10.10.2/32 network=10.10.10.3
R2: /ip add add interface=ether3-to-R4 address=10.10.10.2/32 network=10.10.10.4

R3: /ip add add interface=ether1-to-R1 address=10.10.10.3/32 network=10.10.10.1
R3: /ip add add interface=ether2-to-R2 address=10.10.10.3/32 network=10.10.10.2
R3: /ip add add interface=ether3-to-R4 address=10.10.10.3/32 network=10.10.10.4

R4: /ip add add interface=ether1-to-R1 address=10.10.10.4/32 network=10.10.10.1
R4: /ip add add interface=ether2-to-R2 address=10.10.10.4/32 network=10.10.10.2
R4: /ip add add interface=ether3-to-R3 address=10.10.10.4/32 network=10.10.10.3

Would fully interconnect them, using only 4 addresses. In this particular case, we get 3 times the address utilization efficiency of /31 addressing.

In an 8 router full-mesh the efficiency is even more spectacular, with only 8 addresses needed for /32 addressing, while a whopping 56 addresses would be needed for /31 addressing.

--Eric
This is the way I have tried this with routing protocols ospf and bgp and mpls it all works so my definite recommendation MT<->MT scenario is /32 and use the same IP for all local interfaces on one router. this eliminates the need for loopback interface as the router is the same IP to all interfaces. As MT doesn't work well with /31's the only way to interconnect MT<->OtherVendor is by /30's
 
asy
newbie
Posts: 40
Joined: Thu Oct 18, 2012 2:26 pm

Re: Point-to-point (/31) addresses

Tue Feb 27, 2018 8:36 pm

I read about MT-MT with /32.

As MT doesn't work well with /31's the only way to interconnect MT<->OtherVendor is by /30's
But I need this. I linked MT(/32) - Linux(/31) but I can't run OSPF over it (with Quagga). I tried nbma, broadcast
and point-to-point settings for OSPF but all unsuccessful. The best that I reach (with nbma, from log of Quagga):

OSPF: Packet 172.16.64.58 [Hello:RECV]: NetworkMask mismatch on eth2:172.16.64.59 (configured pref
ix length is 31, but hello packet indicates 32).

eth2/Linux: 172.16.64.59/31

RouterOS:
/ip address
add address=172.16.64.58 interface=ether1 network=172.16.64.59

So, does no way to run OSPF without /30 ?
 
User avatar
mrz
MikroTik Support
MikroTik Support
Posts: 6196
Joined: Wed Feb 07, 2007 12:45 pm
Location: Latvia
Contact:

Re: Point-to-point (/31) addresses

Wed Feb 28, 2018 11:36 am

Linux support /32 so switch to /32 and OSPF will work.
 
asy
newbie
Posts: 40
Joined: Thu Oct 18, 2012 2:26 pm

Re: Point-to-point (/31) addresses

Wed Feb 28, 2018 3:33 pm

Linux support /32 so switch to /32
True. I switched "ip address add 172.16.64.59/31 ..." to "ip address add 172.16.64.59/31 peer 172.16.64.59 ..." and link continued to work. Ok.

and OSPF will work.
But this not. Quagga isn't up neighbor with error (with nbma):

OSPF: interface eth2:172.16.64.59: ospf_read network address is not same [172.16
.64.58]

I attempted to switch ospf configuration to point-to-point. This gave some result: I can see neighbor in Quagga now:

172.16.64.58 1 Init/DROther 37.334s 172.16.64.58 eth2:172.16.64.59 0 0 0

but I doesn'ot see neighbor in RouterOS. :-(
 
User avatar
mrz
MikroTik Support
MikroTik Support
Posts: 6196
Joined: Wed Feb 07, 2007 12:45 pm
Location: Latvia
Contact:

Re: Point-to-point (/31) addresses

Wed Feb 28, 2018 3:38 pm

show your quagga configuration
 
asy
newbie
Posts: 40
Joined: Thu Oct 18, 2012 2:26 pm

Re: Point-to-point (/31) addresses

Wed Feb 28, 2018 4:48 pm

Sorry, I forgot about default firewall after reset configuration on MT. It works, thanks.

Linux:
ip address add 172.16.64.59/32 peer 172.16.64.58 dev eth2
Quagga:
!
  interface eth2
  ip ospf network point-to-point
! 
 router ospf
  ospf router-id 10.10.10.10
!
  network 172.16.64.58/31 area 0.0.0.112
!
  area 0.0.0.112 stub
!  
MT (6.41.2)
/ip address
add address=172.16.64.58 interface=ether1 network=172.16.64.59
/routing ospf area
set [ find default=yes ] disabled=yes
add area-id=0.0.0.112 default-cost=1 inject-summary-lsas=yes name=stub-area1 type=stub
/routing ospf interface
add interface=ether1 network-type=point-to-point
/routing ospf network
add area=stub-area1 network=172.16.64.58/31
 
User avatar
mrz
MikroTik Support
MikroTik Support
Posts: 6196
Joined: Wed Feb 07, 2007 12:45 pm
Location: Latvia
Contact:

Re: Point-to-point (/31) addresses

Wed Feb 28, 2018 5:16 pm

change to
network 172.16.64.58/32 area 0.0.0.112
 
asy
newbie
Posts: 40
Joined: Thu Oct 18, 2012 2:26 pm

Re: Point-to-point (/31) addresses

Thu Mar 01, 2018 9:08 am

change to
network 172.16.64.58/32 area 0.0.0.112
It seems more accurate but it not works: Quagga is not sending OSPF hello.
 
User avatar
indnti
Frequent Visitor
Frequent Visitor
Posts: 75
Joined: Thu Nov 09, 2006 11:53 am

Re: Point-to-point (/31) addresses

Fri Jul 20, 2018 2:48 am

Is there any fundamental reason why mikrotik does not support RFC 3021, so it is compatible with other vendors (cisco) without problems?
 
schadom
Member Candidate
Member Candidate
Posts: 154
Joined: Sun Jun 25, 2017 2:47 am
Location: Austria

Re: Point-to-point (/31) addresses

Sat Sep 29, 2018 3:07 pm

Is there any fundamental reason why mikrotik does not support RFC 3021, so it is compatible with other vendors (cisco) without problems?
Same as with many other things here...
Hundreds of requests by many customers over years and they simple ignore it :-(
 
dcosta
just joined
Posts: 8
Joined: Mon Mar 28, 2016 7:42 pm

Re: Point-to-point (/31) addresses

Tue Nov 27, 2018 1:33 pm

Hello,
Now that Mikrotik addressed the service providers segment with CCR routers, when does Mikrotik plan to support /31 networks?
The majority of routers used by service providers supports /31, so it will be hard to migrate from a previous /31 configuration to Mikrotik CCR routers.
Thanks,
David
 
User avatar
indnti
Frequent Visitor
Frequent Visitor
Posts: 75
Joined: Thu Nov 09, 2006 11:53 am

Re: Point-to-point (/31) addresses

Fri Sep 20, 2019 12:39 pm

Hi

Any News for this?
 
chillisock7
just joined
Posts: 15
Joined: Fri Jun 03, 2016 3:48 pm

Re: Point-to-point (/31) addresses

Fri Jan 31, 2020 9:28 pm

Brilliant :)
I would skip using an actual /31, and just use two /32s. Specify the remote address as the "network", and you should be good to go.

This mechanism is more flexible than using /31s, as the addresses don't need to be adjacent; and more efficient since you can re-use the same address for multiple links on a router.

In your particular case:

R1: /ip add add interface=ether1 address=10.10.10.2/32 network=10.10.10.3
R2: /ip add add interface=ether1 address=10.10.10.3/32 network=10.10.10.2

Will do the trick.

In a more complex hypothetical setup, with four routers connected to each other in a full-mesh of point-to-point ethernets:

R1: /ip add add interface=ether1-to-R2 address=10.10.10.1/32 network=10.10.10.2
R1: /ip add add interface=ether2-to-R3 address=10.10.10.1/32 network=10.10.10.3
R1: /ip add add interface=ether3-to-R4 address=10.10.10.1/32 network=10.10.10.4

R2: /ip add add interface=ether1-to-R1 address=10.10.10.2/32 network=10.10.10.1
R2: /ip add add interface=ether2-to-R3 address=10.10.10.2/32 network=10.10.10.3
R2: /ip add add interface=ether3-to-R4 address=10.10.10.2/32 network=10.10.10.4

R3: /ip add add interface=ether1-to-R1 address=10.10.10.3/32 network=10.10.10.1
R3: /ip add add interface=ether2-to-R2 address=10.10.10.3/32 network=10.10.10.2
R3: /ip add add interface=ether3-to-R4 address=10.10.10.3/32 network=10.10.10.4

R4: /ip add add interface=ether1-to-R1 address=10.10.10.4/32 network=10.10.10.1
R4: /ip add add interface=ether2-to-R2 address=10.10.10.4/32 network=10.10.10.2
R4: /ip add add interface=ether3-to-R3 address=10.10.10.4/32 network=10.10.10.3

Would fully interconnect them, using only 4 addresses. In this particular case, we get 3 times the address utilization efficiency of /31 addressing.

In an 8 router full-mesh the efficiency is even more spectacular, with only 8 addresses needed for /32 addressing, while a whopping 56 addresses would be needed for /31 addressing.

--Eric
 
User avatar
IPANetEngineer
Trainer
Trainer
Posts: 1333
Joined: Fri Aug 10, 2012 6:46 am
Location: Jackson, MS, USA
Contact:

Re: Point-to-point (/31) addresses

Sat Feb 01, 2020 5:52 pm

Just a warning on using two /32 addresses as a workaround for the /31 problem.

We've had a number of problems with OSPF stability using this approach if you're planning on using OSPF for a dynamic routing protocol.
Global - MikroTik Support & Consulting - English | Español | Serbian | Danish +1 855-645-7684
https://iparchitechs.com/ecosystem/mikr ... consulting mikrotiksupport@iparchitechs.com
 
jw1
just joined
Posts: 11
Joined: Thu Jul 14, 2016 8:49 pm

Re: Point-to-point (/31) addresses

Wed May 06, 2020 12:54 am

Working on switching up some /30 to /32 in order to free up some addresses. So far haven't noticed stability issues, but path selection seems a bit odd.
Here's the rundown:
R1 is connected to R2. R1 interface to R2 has a /32 address, for example, 1.1.1.1/32 with network 2.2.2.2. R2 facing R1 is 2.2.2.2/32 with network 1.1.1.1. Connectivity seems OK, but in the routing table on R1, 2.2.2.2 shows up as directly connected, distance 0, but 1.1.1.1 doesn't show up at all. No big deal, just a little odd.
Add R3 and R4. R1 -> R2 -> R3 -> R4 -> back to R1 and add OSPF. Now on the R1 routing table 1.1.1.1 shows up, but as an OSPF route with a distance of 110. Looking in OSPF routes, 1.1.1.1 has a path cost of 20 with a gateway of 2.2.2.2. Odd that a local address would have a path cost of 20, but things still seem to be working, so OK.
Here's the potential gotcha - On R4 routing table the path to 1.1.1.1 has equal preference between going directly from R4-R1 and R4-R3-R2-R1. In the OSPF routes, both options have a path cost of 30 even though 1 path is 1 hop away and the other is 3. All the individual path costs are 10. A traceroute from R4 to 1.1.1.1 chooses the R4-R3-R2-R1 path. To be honest, I doubt I will be needing to connect to the IP address of a PTP link, and the path selection for the loopback address of R1 seems normal, but it is making me wonder if I want to proceed with more switching to /32s. I am thinking about tinkering with a static route on R1 to 1.1.1.1 to see what happens.

(FWIW, these aren't the actual IPs I was using and haven't tested it with these. Also, I doubt if it matters, but the lowest router id for path selection is R3, R4, R2, and then R1)

jw
 
chakphanu
just joined
Posts: 2
Joined: Thu Oct 11, 2018 9:45 am

Re: Point-to-point (/31) addresses

Fri Jun 26, 2020 5:26 pm

Cisco /31 - MT/31 BFD not work
Cisco /31 - MT/32 BFD Work
 
next111
just joined
Posts: 16
Joined: Wed Jan 29, 2020 8:08 pm
Location: ITALY

Re: Point-to-point (/31) addresses

Fri Jul 03, 2020 10:23 pm

serves the / 31 here in Italy is widely used on wan
 
User avatar
TomjNorthIdaho
Forum Guru
Forum Guru
Posts: 1155
Joined: Mon Oct 04, 2010 11:25 pm
Location: North Idaho
Contact:

/31 network between two mikrotik devices - here is how you do it

Sat Aug 01, 2020 2:04 am

/31 network between two mikrotik devices - here is how you do it

First thing - you do not actually use a /31 in the IP address ( this is important )

Here is how you use a /31 network of only two IP address to get two Mikrotik devices to talk to each other.

I am going to demonstrate 192.168.168.0/31 ( This /31 has only two IP address which are 192.168.168.0 and 192.168.168.1 )
Mikrotik #1
- Configure IP address 192.168.168.0 on your first Mikrotik ( example 192.168.168.0 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.1 out interface ether2 ( use the interface name not an IP address )

Mikrotik #2
- Configure IP address 192.168.168.1 on your second Mikrotik ( example 192.168.168.1 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.0 out interface ether2 ( use the interface name not an IP address )

Thats it , the two mikrotiks can ping each other and pass traffic

So , why burn up 4 IPv4 address on a link with only two Mikrotiks on the link. Each /30 link between two Mikrotik devices can now be used for two different /31 links ( twice as many link using the same number of IP address ).

North Idaho Tom Jones
 
User avatar
CZFan
Forum Guru
Forum Guru
Posts: 1980
Joined: Sun Oct 09, 2016 8:25 pm
Location: South Africa, Krugersdorp (Home town of Brad Binder)
Contact:

Re: Point-to-point (/31) addresses

Mon Aug 03, 2020 1:02 am

@TomjNorthidaho, some creative thinking there, I might pop your balloon though :-)
That method is called point to point addressing and but should work
MTCNA, MTCTCE, MTCRE & MTCINE
 
User avatar
TomjNorthIdaho
Forum Guru
Forum Guru
Posts: 1155
Joined: Mon Oct 04, 2010 11:25 pm
Location: North Idaho
Contact:

Re: Point-to-point (/31) addresses

Mon Aug 03, 2020 5:26 pm

@TomjNorthidaho, some creative thinking there, I might pop your balloon though :-)
That method is called point to point addressing and but should work
One thing I have not tested is a /31 between a Mikrotik and a Cisco , or between a Mikrotik and a PfSense virtual router/firewall.

North Idaho Tom Jones
 
User avatar
IPANetEngineer
Trainer
Trainer
Posts: 1333
Joined: Fri Aug 10, 2012 6:46 am
Location: Jackson, MS, USA
Contact:

Re: /31 network between two mikrotik devices - here is how you do it

Tue Aug 04, 2020 6:52 pm

/31 network between two mikrotik devices - here is how you do it

First thing - you do not actually use a /31 in the IP address ( this is important )

Here is how you use a /31 network of only two IP address to get two Mikrotik devices to talk to each other.

I am going to demonstrate 192.168.168.0/31 ( This /31 has only two IP address which are 192.168.168.0 and 192.168.168.1 )
Mikrotik #1
- Configure IP address 192.168.168.0 on your first Mikrotik ( example 192.168.168.0 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.1 out interface ether2 ( use the interface name not an IP address )

Mikrotik #2
- Configure IP address 192.168.168.1 on your second Mikrotik ( example 192.168.168.1 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.0 out interface ether2 ( use the interface name not an IP address )

Thats it , the two mikrotiks can ping each other and pass traffic

So , why burn up 4 IPv4 address on a link with only two Mikrotiks on the link. Each /30 link between two Mikrotik devices can now be used for two different /31 links ( twice as many link using the same number of IP address ).

North Idaho Tom Jones

The main issue that i've run into with this method is routing protocol instability. I've had intermittent issues with OSPF adjacency instability on a number of networks that used this addressing method. As soon as we migrated to /30 or larger prefix, the issues went away.
Global - MikroTik Support & Consulting - English | Español | Serbian | Danish +1 855-645-7684
https://iparchitechs.com/ecosystem/mikr ... consulting mikrotiksupport@iparchitechs.com
 
User avatar
TomjNorthIdaho
Forum Guru
Forum Guru
Posts: 1155
Joined: Mon Oct 04, 2010 11:25 pm
Location: North Idaho
Contact:

Re: /31 network between two mikrotik devices - here is how you do it

Wed Aug 05, 2020 12:26 am

/31 network between two mikrotik devices - here is how you do it

First thing - you do not actually use a /31 in the IP address ( this is important )

Here is how you use a /31 network of only two IP address to get two Mikrotik devices to talk to each other.

I am going to demonstrate 192.168.168.0/31 ( This /31 has only two IP address which are 192.168.168.0 and 192.168.168.1 )
Mikrotik #1
- Configure IP address 192.168.168.0 on your first Mikrotik ( example 192.168.168.0 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.1 out interface ether2 ( use the interface name not an IP address )

Mikrotik #2
- Configure IP address 192.168.168.1 on your second Mikrotik ( example 192.168.168.1 ( no / after IP address ) will be on ether2 )
- Add the route 192.168.168.0 out interface ether2 ( use the interface name not an IP address )

Thats it , the two mikrotiks can ping each other and pass traffic

So , why burn up 4 IPv4 address on a link with only two Mikrotiks on the link. Each /30 link between two Mikrotik devices can now be used for two different /31 links ( twice as many link using the same number of IP address ).

North Idaho Tom Jones

The main issue that i've run into with this method is routing protocol instability. I've had intermittent issues with OSPF adjacency instability on a number of networks that used this addressing method. As soon as we migrated to /30 or larger prefix, the issues went away.
I wish that Mikrotik would support a /31 natively on a /31 network between any two Mikrotiks.
With IPv4 exhausted and no more new IPv4 blocks available, it is becoming increasingly important-urgent-required to natively support /31 networks , without the need to do any fancy work-arounds.
I've run into several problems with peer-connections where a remote party is wanting to use a /31 ( a /31 network for BGP peering ). I gave up trying to make it work and had to fight to use a /30 for BGP peering - what a friggen nightmare that was !

North Idaho Tom Jones
 
User avatar
sjwrick
Frequent Visitor
Frequent Visitor
Posts: 82
Joined: Tue Jul 25, 2006 10:12 pm

Re: Point-to-point (/31) addresses

Fri Aug 07, 2020 5:23 pm

So I am on the verge of setting up a BGP with my 1st peer and he mentioned using a /31. I am going to assume he is using a Cisco. I am a Mikrotik shop.

You are saying that Cisco and Mikrotik are not able to use BGP on a /31?

Rick
 
User avatar
TomjNorthIdaho
Forum Guru
Forum Guru
Posts: 1155
Joined: Mon Oct 04, 2010 11:25 pm
Location: North Idaho
Contact:

Re: Point-to-point (/31) addresses

Fri Aug 07, 2020 6:27 pm

So I am on the verge of setting up a BGP with my 1st peer and he mentioned using a /31. I am going to assume he is using a Cisco. I am a Mikrotik shop.

You are saying that Cisco and Mikrotik are not able to use BGP on a /31?

Rick
When I was adding a second BGP peer, I was given one IP address from a /31. I had a Mikrotik ( I don't know what the upstream BGP router was ). I tried and tried and tried using a /31 and at the time I could not get it to even ping his /31 IP address. This was my first attempt at trying to use a /31.
As a test, I switched to a Cisco router and the /31 worked , but I wanted to use a Mikrotik router for my BGP. I was finally able to get the BGP peering network changed from a /31 to a /30 and suddenly everything started working on my Mikrotik router.

Sooo , although it might be possible to make a Mikrotik function on a /31 network for BGP peering, I suggest using a traditional /30 network for BGP peering. A /30 network for BGP peering will give you the ability to change your Mikrotik BGP peering router to any other BGP peering router. If you setup a /31 network for BGP peering , then you might get stuck to only being able to use routers which natively support /31 networks for BGP peering.

So , IMO - for BGP peering , I suggest using existing traditional tried-and-true /30.

North Idaho Tom Jones
 
pe1chl
Forum Guru
Forum Guru
Posts: 7236
Joined: Mon Jun 08, 2015 12:09 pm

Re: Point-to-point (/31) addresses

Fri Aug 07, 2020 7:59 pm

Of course when you have only a simple peering with some other world where they are using /31, you can just change your own side to be a /30 or even larger to
make your side contain the addresses from the /31 and neither of them being the "network" or "broadcast" address on that subnet.
This will make some addresses unreachable, but when the /31 is from a range that is just used for such peerings, that usually does not matter.

When you want to setup your local shop using /31 and have a mix of routers that allow that and MikroTiks that don't, this could be more of a problem because there
is more risk fo connectivity issues in that case.

Who is online

Users browsing this forum: No registered users and 19 guests