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LDP show "No Label"

Mohammad Nasim
Level 1
Level 1

hello everybody,

i am using GNS3 1.4.5 .. IOU image to create a simple MPLS lab.

routes are propagated via OSPF and pingable, but show mpls forwarding-table gives me below output.

P-11#show mpls forwarding-table
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop    
Label      Label      or Tunnel Id     Switched      interface              
16         No Label   10.1.1.1/32      0             Et0/0.111  10.1.111.1  
17         No Label   10.1.109.0/24    0             Et0/0.111  10.1.111.1  
18         No Label   10.1.104.0/24    0             Et0/0.111  10.1.111.1  
19         No Label   10.1.101.0/24    0             Et0/0.111  10.1.111.1  
20         No Label   10.1.10.10/32    0             Et0/0.111  10.1.111.1 

10 Replies 10

Victor Acevedo
Cisco Employee
Cisco Employee

Hello Mohammad,

Do we have any LDP neighborships established on P-11? Can you paste your interface configurations as well as the following output:

- sh mpls ldp neighborship

- sh mpls ldp discovery

- sh mpls ldp bindings

Thx,

Victor Hugo Acevedo

here is your request, and be noted that ldp neighborship is not established between any two P routers.

configuration

===========

ip cef

!

mpls label protocol ldp
mpls ldp discovery hello interval 1

!

interface Loopback0
 ip address 10.1.11.11 255.255.255.255
!
interface Ethernet0/0
 no ip address
 mpls ip
!
interface Ethernet0/0.111
 encapsulation dot1Q 111
 ip address 10.1.111.11 255.255.255.0
 mpls ip  
!
interface Ethernet0/0.112
 encapsulation dot1Q 112
 ip address 10.1.112.11 255.255.255.0
 mpls ip
!
interface Ethernet0/0.113
 encapsulation dot1Q 113
 ip address 10.1.113.11 255.255.255.0
 mpls ip

!

!
router ospf 1
 router-id 10.1.11.11
 network 10.1.0.0 0.0.255.255 area 0
!

mpls ldp router-id Loopback0

!

Status

======

P-11#show mpls ldp nei
P-11#show mpls ldp dis
P-11#show mpls ldp discovery
 Local LDP Identifier:
    10.1.11.11:0
    Discovery Sources:
    Interfaces:
        Ethernet0/0 (ldp): xmit
        Ethernet0/0.111 (ldp): xmit
        Ethernet0/0.112 (ldp): xmit
        Ethernet0/0.113 (ldp): xmit
P-11#show mpls ldp bin
P-11#show mpls ldp bindings
  lib entry: 10.1.1.1/32, rev 15
        local binding:  label: 20
  lib entry: 10.1.10.10/32, rev 13
        local binding:  label: 19
  lib entry: 10.1.11.11/32, rev 11
        local binding:  label: imp-null
  lib entry: 10.1.101.0/24, rev 21
        local binding:  label: 23
  lib entry: 10.1.104.0/24, rev 19
        local binding:  label: 22
  lib entry: 10.1.109.0/24, rev 17
        local binding:  label: 21
  lib entry: 10.1.111.0/24, rev 7
        local binding:  label: imp-null
  lib entry: 10.1.112.0/24, rev 8
        local binding:  label: imp-null
  lib entry: 10.1.113.0/24, rev 9
        local binding:  label: imp-null
P-11#show mpls fo           
P-11#show mpls forwarding-table
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop    
Label      Label      or Tunnel Id     Switched      interface              
19         No Label   10.1.10.10/32    0             Et0/0.111  10.1.111.1  
20         No Label   10.1.1.1/32      0             Et0/0.111  10.1.111.1  
21         No Label   10.1.109.0/24    0             Et0/0.111  10.1.111.1  
22         No Label   10.1.104.0/24    0             Et0/0.111  10.1.111.1  
23         No Label   10.1.101.0/24    0             Et0/0.111  10.1.111.1  
P-11#

Hello Mohammad,

Yes, it seems that is our problem here. Without LDP neighborships we will not receive labels. Can we make sure we have routes for the /32 Loopback addresses of our other devices? 

It seems that we are transmitting LDP hellos but never receive anything from our peers. Please make sure they also have "mpls ip" enable don the interfaces and have /32 loopback addresses and have a route back to our /32 loopback address.

P-11#show mpls ldp discovery
 Local LDP Identifier:
    10.1.11.11:0
    Discovery Sources:
    Interfaces:
        Ethernet0/0 (ldp): xmit         <<<< Transmit only,  
        Ethernet0/0.111 (ldp): xmit  <<< Nothing is being received 
        Ethernet0/0.112 (ldp): xmit  <<<
        Ethernet0/0.113 (ldp): xmit  <<< 

Thx,

Victor Hugo Acevedo

Dear Victor,

sorry for late answer, i was checking the lab with colleagues.

i cannot see anything wrong; OSPF is propagating routes perfectly and they are pingable; also, mpls ip is enabled globaly, on main interface, and on subinterfaces.


P-01#show ip route ospf

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
O        10.1.10.10/32 [110/11] via 10.1.101.10, 00:01:46, Ethernet0/0.101
O        10.1.11.11/32 [110/11] via 10.1.111.11, 00:01:56, Ethernet0/0.111
O        10.1.104.0/24 [110/20] via 10.1.101.10, 00:01:46, Ethernet0/0.101
O        10.1.109.0/24 [110/20] via 10.1.101.10, 00:01:46, Ethernet0/0.101
O        10.1.112.0/24 [110/20] via 10.1.111.11, 00:01:56, Ethernet0/0.111
O        10.1.113.0/24 [110/20] via 10.1.111.11, 00:01:56, Ethernet0/0.111
P-01#ping 10.1.10.10 re 2 size 1500
Type escape sequence to abort.
Sending 2, 1500-byte ICMP Echos to 10.1.10.10, timeout is 2 seconds:
!! <<< indicates back routes are working fine
Success rate is 100 percent (2/2), round-trip min/avg/max = 2/2/2 ms
P-01#ping 10.1.11.11 re 2 size 1500
Type escape sequence to abort.
Sending 2, 1500-byte ICMP Echos to 10.1.11.11, timeout is 2 seconds:
!! <<< indicates back routes are working fine
Success rate is 100 percent (2/2), round-trip min/avg/max = 2/2/2 ms
P-01#

I believe the problem is in GNS3.

moreover, UNL loads routers, and then they stop; IOU-Web v2.0 do not load labs, but v22.0 is working fine.

i tried 7200 images and IOU L3 images.

My problem is in simulation. did you see this problem before?!!!!

Hey Mohammad,

It could be a GNS3 problem. Does the image/licenses used support MPLS on these routers? Just to rule out a configuration problem, Can you paste the following from P-01 router

- sh mpls ldp neighborship

- sh mpls ldp discovery

Thx,

Victor Hugo Acevedo

Hew Victor,

1st regarding show commands, it shows the same exact output of P-11 posted above, except for interface names.

2nd regarding license, YES.

3rd regarding simulation, not only GNS3, but also many simulators misbehave with me, although i am using a Core-i7 labtop.

Hey Mohammad,

So it shows it is only seeing "xmit" only and no rcv?

Can you try one last thing for me? Can you please ping from P-01 from P-11, sourcing it from it's loopback interface? and vice versa? 

Also, remove "mpls ip" from Eth0/0 physical interface. We only need this on the subinterfaces. 

Thx,

Victor Hugo Acevedo

Hey Victor,

thanks for you patience. below is your requested Ping:

P-01#ping 10.1.11.11 source 10.1.1.1 size 1500 repeat 22
Type escape sequence to abort.
Sending 22, 1500-byte ICMP Echos to 10.1.11.11, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (22/22), round-trip min/avg/max = 1/2/6 ms

also, i did the following changes:

i removed mpls ip from the physical interface

i hard-coded duplex of E0/0 on all P-xx routers

no change in LDP neighborship or discovery.

P-01#show mpls ldp dis
 Local LDP Identifier:
    10.1.1.1:0
    Discovery Sources:
    Interfaces:
        Ethernet0/0.101 (ldp): xmit
        Ethernet0/0.111 (ldp): xmit

After all, thanks for your long support.

it seems my Laptop doesn't handle simulation well as i faced many troubles with Juniper Mx and SRX series. anso, UNL is not working fine with me. I mayy try another machine and feed you back if you wish.

one last-thing

below is my physical topology, if it makes sense

Hey Mohammad,

Not a problem. That is interesting, do you see this same issue if you connect the routers back to back, omitting the switch in the middle? 

Thx,

Victor Hugo Acevedo

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