Mpls ospf and winbox error

RouterOS Forwarding Protocols
1

Hello,
I have created a network between two routers (ospf and mpls), with the ospf all good, but when I activate the mpls in the interfacez, I can access the other router via winbox but it does not show me anything at all and after a while the connection is lost.
Router 1
/routing ospf area
add area-id=1.0.1.0 instance=ospf0 name=area0
/routing ospf instance
add distribute-default=if-installed-as-type-1 mpls-te-area=area0 mpls-te-router-id=loopback-ospf name=ospf0 redistribute-connected=as-type-1
redistribute-other-ospf=as-type-1 redistribute-static=as-type-1 router-id=10.255.255.1
/routing ospf interface
add interface=ether1 network-type=point-to-point
/routing ospf network
add area=area0 network=2.2.2.0/30
add area=area0 network=10.255.255.1/32

/mpls ldp
set enabled=yes lsr-id=10.255.255.1 transport-address=10.255.255.1
/mpls ldp advertise-filter
add prefix=10.255.255.0/24
add advertise=no prefix=0.0.0.0/24
/mpls ldp interface
add interface=ether1
/mpls traffic-eng interface
add bandwidth=1Gbps interface=ether1

Interfaz R1
MUT 1500
L2 MTU 1592
MPLS MTU 1508

Router2
/routing ospf area
add area-id=1.0.1.0 instance=ospf0 name=area0
/routing ospf instance
add distribute-default=if-installed-as-type-1 mpls-te-area=area0 mpls-te-router-id=loopback-ospf name=ospf0 redistribute-connected=as-type-1 router-id=10.255.255.2
/routing ospf interface
add interface=ether5 network-type=point-to-point
/routing ospf network
add area=area0 network=2.2.2.0/30
add area=area0 network=10.255.255.2/32

/mpls ldp
set enabled=yes hop-limit=0 lsr-id=10.255.255.2 path-vector-limit=0 transport-address=10.255.255.2
/mpls ldp advertise-filter
add prefix=10.255.255.0/24
add advertise=no
/mpls ldp interface
add interface=ether5
/mpls traffic-eng interface
add bandwidth=1Gbps interface=ether5

Interfaz R2
MTU 1500
L2 MTU 1592
MPLS MTU 1508





What am I doing wrong?

2

Hi rgear13, I think that you are experimenting some MTU issues, most common errors with MPLS are those, so i’ll check that, remember that there are three kinds of MTU, L3MTU, L2MTU and MPLS-MTU, and that must be well configured behind the hole path. You may able to find some extra information at: https://wiki.mikrotik.com/wiki/Manual:Maximum_Transmission_Unit_on_RouterBoards#MPLS.2FLayer-2.5.2FL2.5_MTU

3

Thank you, I will review the information you provide.

4

Solve the problem by lowering the mpls mtu below ip mtu.
ip mtu 1500
mpls mtu 1499

only that in the information provided I found this:

When MPLS is used as plain replacement for IP routing, only one label is attached to every packet, therefore packet size increases by 4 bytes, we have the situation with two MPLS labels. In order to be able to forward standard size (1500 bytes) IP packet without fragmentation, MPLS MTU must be set to at least 1508 for two MPLS labels.

5

I’ll check if all of the path the MTU is configured right, as I told you before, there are three kinds of MTU, and you may setup as follows:

  • L3 MTU < MPLS MTU <= L2 MTU

MPLS MTU can be configured with at least 1508bytes, and you may want to check if Layer2 switches in the middle can handle this frames too.

6

Thanks for your time, I have solved the problem.