Routing

Dear all,

I've tried to set up LDP tuunelling over RSVP at R1 & R3. But, no remote LDP route can be recevied at both R1 & R3. Below please find R1, R2 & R3 configuation for your reference. Thanks!

R1--(OSPF area 0)-----R2-----(OSPF area 1 NSSA)-----R3


R1 configruation
test@Lab-M# show logical-systems R1
interfaces {
    lt-0/1/0 {
        unit 12 {
            encapsulation ethernet;
            peer-unit 21;
            family inet {
                address 10.100.12.1/30;
            }
            family mpls;
        }
    }
    lo0 {
        unit 1 {
            family inet {
                address 10.100.0.1/32;
            }
        }
    }
}
protocols {
    rsvp {
        interface lt-0/1/0.12;
    }
    mpls {
        label-switched-path R1-R2 {
            to 10.100.0.2;
            no-cspf;
        }
        label-switched-path R1-R3 {
            to 10.100.0.3;
            ldp-tunneling;
            no-cspf;
        }
        interface all;
    }
    ospf {
        area 0.0.0.0 {
            interface lo0.1 {
                passive;
            }
            interface lt-0/1/0.12;
        }
    }
    ldp {
        interface lo0.1;
    }
}
======================================================================
R2 configruation

test@Lab-M# show logical-systems R2    
interfaces {
    lt-0/1/0 {
        unit 21 {
            encapsulation ethernet;
            peer-unit 12;
            family inet {
                address 10.100.12.2/30;
            }
            family mpls;
        }
        unit 23 {
            encapsulation ethernet;
            peer-unit 32;
            family inet {
                address 10.100.23.1/30;
            }
            family mpls;
        }
    }
    lo0 {
        unit 2 {
            family inet {
                address 10.100.0.2/32;
            }
        }
    }
}
protocols {
    rsvp {
        interface lt-0/1/0.21;
        interface lt-0/1/0.23;
    }
    mpls {
        label-switched-path R2-R1 {
            to 10.100.0.1;
            no-cspf;
        }
        label-switched-path R2-R3 {
            to 10.100.0.3;
            no-cspf;
        }
        interface lt-0/1/0.21;
        interface lt-0/1/0.23;
    }
    ospf {
        area 0.0.0.0 {
            interface lo0.2 {
                passive;
            }
            interface lt-0/1/0.21;
        }
        area 0.0.0.1 {
            nssa {
                default-lsa;
            }
            interface lt-0/1/0.23;
        }
    }
}

======================================================================
R3 configruation
test@Lab-M# show logical-systems R3    
interfaces {
    lt-0/1/0 {
        unit 32 {
            encapsulation ethernet;
            peer-unit 23;
            family inet {
                address 10.100.23.2/30;
            }
            family mpls;
        }
    }
    lo0 {
        unit 3 {
            family inet {
                address 10.100.0.3/32;
            }
        }
    }
}
protocols {
    rsvp {
        interface all;
    }
    mpls {
        label-switched-path R3-R2 {
            to 10.100.0.2;
            no-cspf;
        }
        label-switched-path R3-R1 {
            to 10.100.0.1;
            ldp-tunneling;
            no-cspf;
        }
        interface all;
    }
    ospf {
        area 0.0.0.1 {
            nssa;
            interface all;
        }
    }
    ldp {
        interface lo0.3;
    }
}

test@Lab-M# run show ldp session logical-system R1
  Address           State        Connection     Hold time
10.100.0.3          Operational  Open             22

[edit]
test@Lab-M# run show ldp interface logical-system R1  
Interface            Label space ID        Nbr count   Next hello
lo0.1                10.100.0.1:0             1           0

[edit]
test@Lab-M# run show ldp database logical-system R1    
Input label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.3/32

Output label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.1/32

test@Lab-M# run show route protocol ldp logical-system R1  

inet.0: 7 destinations, 7 routes (7 active, 0 holddown, 0 hidden)

inet.3: 3 destinations, 5 routes (2 active, 0 holddown, 3 hidden)

mpls.0: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)

[edit]
test@Lab-M# run show ldp session logical-system R3
  Address           State        Connection     Hold time
10.100.0.1          Operational  Open             26

[edit]
test@Lab-M# run show ldp interface logical-system R3  
Interface            Label space ID        Nbr count   Next hello
lo0.3                10.100.0.3:0             1           0

[edit]
test@Lab-M# run show ldp database logical-system R3     
Input label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
      3     10.100.0.1/32

Output label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
      3     10.100.0.3/32

Thanks,

Patrick

Hi Patrick,

AFAICS you just have both R1 and R3 as targeted neighbors on each side, advertising their own loopback address as FECs in the LDP database, without any other directly connected neighbors or explicit LDP egress policies.

Which other FECs would you expect or want to advertise at each side?

Thanks,

Gonzalo

Hi Gonzalo,

Thanks a lot for your response.  Actually, there have another CE routers/PE( support LDP only)  connect to both R1 & R3 for L2 VPLS servcie.  I expect both R1 & R3 can learn both's loopack FEC each other.  

I tried to change the ospf area 1 (NSSA) to ospf areo 0 at R2-R3.  Then, it works and all FEC can be leraned each other.   I don't know why it not work when R2-R3 using NSSA.  Thanks a lot!

Best Regards,

Patrick

Hi Patrick,

an issue you may need to consider here is that for an LDP FEC to become valid and appear as route in inet.3, there needs to be another exact match with valid route (/32) in inet.0 (i.e. distributed by OSPF in your case) per default, because LDP inherently depends on that for the path calculation.

Could you please provide a more complete diagram or topology from this use case including all PEs? Could you also provide the OSPF and LDP databases in both cases (with and without the NSSA) at both systems?

Thanks,

Gonzalo

Hi Gonzalo,
Below please find network diagram and ospf/LDP database of R1,R3&R5 for your reference.
After changing the link(R2-R3) from NSSA to OSPF area 0, R3 have FEC of R1,R4 & R5.  Thanks a lot!


OSPF with NSSA
====================================================================================
cwuser@Lab-M# run show ospf database logical-system R1  

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router  *10.100.0.1       10.100.0.1       0x80000038   106  0x22 0xd8c   60
Router   10.100.0.2       10.100.0.2       0x80000038   107  0x22 0x108e  48
Router   10.100.0.3       10.100.0.3       0x80000006  1573  0x22 0x6159  48
Router   10.100.0.4       10.100.0.4       0x80000007   107  0x22 0xb90f  48
Network  10.100.12.2      10.100.0.2       0x80000024  2822  0x22 0x9cb0  32
Network  10.100.14.2      10.100.0.4       0x80000003   578  0x22 0xd097  32
Network  10.100.23.2      10.100.0.3       0x80000002  1641  0x22 0x79e7  32
Summary  10.100.0.3       10.100.0.2       0x80000001   107  0x22 0xb4a5  28
Summary  10.100.0.5       10.100.0.2       0x80000001   107  0x22 0xaaac  28
Summary  10.100.23.0      10.100.0.2       0x80000001   355  0x22 0xc286  28
Summary  10.100.35.0      10.100.0.2       0x80000001   107  0x22 0x48f3  28

[edit]
cwuser@Lab-M# run show ospf database logical-system R3    

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   10.100.0.2       10.100.0.2       0x80000005   110  0x20 0xd669  36
Router  *10.100.0.3       10.100.0.3       0x8000000c   109  0x20 0x1969  60
Router   10.100.0.5       10.100.0.5       0x80000005   110  0x20 0x8917  48
Network  10.100.23.1      10.100.0.2       0x80000001   110  0x20 0xadb8  32
Network *10.100.35.1      10.100.0.3       0x80000001   357  0x20 0x490d  32
Summary  10.100.0.1       10.100.0.2       0x80000001   358  0x20 0xe677  28
Summary  10.100.0.2       10.100.0.2       0x80000001   358  0x20 0xd28b  28
Summary  10.100.0.4       10.100.0.2       0x80000001   358  0x20 0xd287  28
Summary  10.100.12.0      10.100.0.2       0x80000001   358  0x20 0x5afb  28
Summary  10.100.14.0      10.100.0.2       0x80000001   358  0x20 0x4e05  28

[edit]
cwuser@Lab-M# run show ospf database logical-system R5    

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   10.100.0.2       10.100.0.2       0x80000005   114  0x20 0xd669  36
Router   10.100.0.3       10.100.0.3       0x8000000c   113  0x20 0x1969  60
Router  *10.100.0.5       10.100.0.5       0x80000005   112  0x20 0x8917  48
Network  10.100.23.1      10.100.0.2       0x80000001   114  0x20 0xadb8  32
Network  10.100.35.1      10.100.0.3       0x80000001   361  0x20 0x490d  32
Summary  10.100.0.1       10.100.0.2       0x80000001   362  0x20 0xe677  28
Summary  10.100.0.2       10.100.0.2       0x80000001   362  0x20 0xd28b  28
Summary  10.100.0.4       10.100.0.2       0x80000001   362  0x20 0xd287  28
Summary  10.100.12.0      10.100.0.2       0x80000001   362  0x20 0x5afb  28
Summary  10.100.14.0      10.100.0.2       0x80000001   362  0x20 0x4e05  28

cwuser@Lab-M# run show ldp database logical-system R1
Input label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.3/32
 299808     10.100.0.5/32

Output label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.1/32
 299824     10.100.0.4/32

Input label database, 10.100.0.1:0--10.100.0.4:0
  Label     Prefix
 299776     10.100.0.1/32
      3     10.100.0.4/32

Output label database, 10.100.0.1:0--10.100.0.4:0
  Label     Prefix
      3     10.100.0.1/32
 299824     10.100.0.4/32

[edit]
cwuser@Lab-M# run show ldp database logical-system R3    
Input label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
      3     10.100.0.1/32
 299824     10.100.0.4/32

Output label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
      3     10.100.0.3/32
 299808     10.100.0.5/32

Input label database, 10.100.0.3:0--10.100.0.5:0
  Label     Prefix
 299776     10.100.0.3/32
      3     10.100.0.5/32

Output label database, 10.100.0.3:0--10.100.0.5:0
  Label     Prefix
      3     10.100.0.3/32
 299808     10.100.0.5/32

[edit]
cwuser@Lab-M# run show ldp database logical-system R5    
Input label database, 10.100.0.5:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.3/32
 299808     10.100.0.5/32

Output label database, 10.100.0.5:0--10.100.0.3:0
  Label     Prefix
 299776     10.100.0.3/32
      3     10.100.0.5/32


[edit]
cwuser@Lab-M# run show route protocol ldp logical-system R3

inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)

inet.3: 6 destinations, 8 routes (3 active, 0 holddown, 5 hidden)
+ = Active Route, - = Last Active, * = Both

10.100.0.5/32      *[LDP/9] 00:08:58, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35

mpls.0: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

299808             *[LDP/9] 00:08:58, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35, Pop      
299808(S=0)        *[LDP/9] 00:08:58, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35, Pop     




OSPF without NSSA
====================================================================================
cwuser@Lab-M# run show ospf database logical-system R1

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router  *10.100.0.1       10.100.0.1       0x80000039    97  0x22 0xb8d   60
Router   10.100.0.2       10.100.0.2       0x8000003c    58  0x22 0x91ed  60
Router   10.100.0.3       10.100.0.3       0x80000008    59  0x22 0xba7c  36
Router   10.100.0.4       10.100.0.4       0x80000008    98  0x22 0xb710  48
Network  10.100.12.2      10.100.0.2       0x80000025   333  0x22 0x9ab1  32
Network  10.100.14.2      10.100.0.4       0x80000003  1044  0x22 0xd097  32
Network  10.100.23.2      10.100.0.3       0x80000004    59  0x22 0x75e9  32
Summary  10.100.0.3       10.100.0.3       0x80000001    99  0x22 0xa4b5  28
Summary  10.100.0.5       10.100.0.3       0x80000001    99  0x22 0x9abc  28
Summary  10.100.35.0      10.100.0.3       0x80000001    99  0x22 0x3804  28

[edit logical-systems R3]
cwuser@Lab-M# run show ospf database logical-system R3         

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   10.100.0.1       10.100.0.1       0x80000039   102  0x22 0xb8d   60
Router   10.100.0.2       10.100.0.2       0x8000003c    61  0x22 0x91ed  60
Router  *10.100.0.3       10.100.0.3       0x80000008    60  0x22 0xba7c  36
Router   10.100.0.4       10.100.0.4       0x80000008   103  0x22 0xb710  48
Network  10.100.12.2      10.100.0.2       0x80000025   336  0x22 0x9ab1  32
Network  10.100.14.2      10.100.0.4       0x80000003  1049  0x22 0xd097  32
Network *10.100.23.2      10.100.0.3       0x80000004    60  0x22 0x75e9  32
Summary *10.100.0.3       10.100.0.3       0x80000001   100  0x22 0xa4b5  28
Summary *10.100.0.5       10.100.0.3       0x80000001   100  0x22 0x9abc  28
Summary *10.100.35.0      10.100.0.3       0x80000001   100  0x22 0x3804  28

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   10.100.0.2       10.100.0.2       0x80000005   576  0x20 0xd669  36
Router  *10.100.0.3       10.100.0.3       0x8000000d   100  0x20 0x7428  48
Router   10.100.0.5       10.100.0.5       0x80000006   101  0x20 0x8718  48
Network  10.100.23.1      10.100.0.2       0x80000001   576  0x20 0xadb8  32
Network *10.100.35.1      10.100.0.3       0x80000001   823  0x20 0x490d  32
Summary  10.100.0.1       10.100.0.2       0x80000002   106  0x20 0xe478  28
Summary *10.100.0.1       10.100.0.3       0x80000003    46  0x20 0xe673  28
Summary  10.100.0.2       10.100.0.2       0x80000001   824  0x20 0xd28b  28
Summary *10.100.0.2       10.100.0.3       0x80000003    46  0x20 0xd287  28
Summary  10.100.0.4       10.100.0.2       0x80000001   824  0x20 0xd287  28
Summary *10.100.0.4       10.100.0.3       0x80000003    46  0x20 0xd283  28
Summary  10.100.12.0      10.100.0.2       0x80000001   824  0x20 0x5afb  28
Summary *10.100.12.0      10.100.0.3       0x80000003    46  0x20 0x5af7  28
Summary  10.100.14.0      10.100.0.2       0x80000001   824  0x20 0x4e05  28
Summary *10.100.14.0      10.100.0.3       0x80000003    46  0x20 0x4e01  28
Summary *10.100.23.0      10.100.0.3       0x80000001   100  0x20 0xda6f  28

[edit logical-systems R3]
cwuser@Lab-M# run show ospf database logical-system R5    

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   10.100.0.2       10.100.0.2       0x80000005   579  0x20 0xd669  36
Router   10.100.0.3       10.100.0.3       0x8000000d   103  0x20 0x7428  48
Router  *10.100.0.5       10.100.0.5       0x80000006   102  0x20 0x8718  48
Network  10.100.23.1      10.100.0.2       0x80000001   579  0x20 0xadb8  32
Network  10.100.35.1      10.100.0.3       0x80000001   826  0x20 0x490d  32
Summary  10.100.0.1       10.100.0.2       0x80000002   109  0x20 0xe478  28
Summary  10.100.0.1       10.100.0.3       0x80000003    49  0x20 0xe673  28
Summary  10.100.0.2       10.100.0.2       0x80000001   827  0x20 0xd28b  28
Summary  10.100.0.2       10.100.0.3       0x80000003    49  0x20 0xd287  28
Summary  10.100.0.4       10.100.0.2       0x80000001   827  0x20 0xd287  28
Summary  10.100.0.4       10.100.0.3       0x80000003    49  0x20 0xd283  28
Summary  10.100.12.0      10.100.0.2       0x80000001   827  0x20 0x5afb  28
Summary  10.100.12.0      10.100.0.3       0x80000003    49  0x20 0x5af7  28
Summary  10.100.14.0      10.100.0.2       0x80000001   827  0x20 0x4e05  28
Summary  10.100.14.0      10.100.0.3       0x80000003    49  0x20 0x4e01  28
Summary  10.100.23.0      10.100.0.3       0x80000001   103  0x20 0xda6f  28

cwuser@Lab-M# run show ldp database logical-system R1
Input label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
 299840     10.100.0.1/32
      3     10.100.0.3/32
 299856     10.100.0.4/32
 299824     10.100.0.5/32

Output label database, 10.100.0.1:0--10.100.0.3:0
  Label     Prefix
      3     10.100.0.1/32
 299840     10.100.0.3/32
 299824     10.100.0.4/32
 299856     10.100.0.5/32

Input label database, 10.100.0.1:0--10.100.0.4:0
  Label     Prefix
 299776     10.100.0.1/32
 299792     10.100.0.3/32
      3     10.100.0.4/32
 299808     10.100.0.5/32

Output label database, 10.100.0.1:0--10.100.0.4:0
  Label     Prefix
      3     10.100.0.1/32
 299840     10.100.0.3/32
 299824     10.100.0.4/32
 299856     10.100.0.5/32

[edit logical-systems R3]
cwuser@Lab-M# run show ldp database logical-system R3    
Input label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
      3     10.100.0.1/32
 299840     10.100.0.3/32
 299824     10.100.0.4/32
 299856     10.100.0.5/32

Output label database, 10.100.0.3:0--10.100.0.1:0
  Label     Prefix
 299840     10.100.0.1/32
      3     10.100.0.3/32
 299856     10.100.0.4/32
 299824     10.100.0.5/32

Input label database, 10.100.0.3:0--10.100.0.5:0
  Label     Prefix
 299808     10.100.0.1/32
 299792     10.100.0.3/32
 299824     10.100.0.4/32
      3     10.100.0.5/32

Output label database, 10.100.0.3:0--10.100.0.5:0
  Label     Prefix
 299840     10.100.0.1/32
      3     10.100.0.3/32
 299856     10.100.0.4/32
 299824     10.100.0.5/32

cwuser@Lab-M# run show route protocol ldp logical-system R3

inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)

inet.3: 6 destinations, 10 routes (4 active, 0 holddown, 5 hidden)
+ = Active Route, - = Last Active, * = Both

10.100.0.1/32       [LDP/9] 00:01:52, metric 1
                    > to 10.100.23.1 via lt-0/1/0.32, label-switched-path R3-R1
10.100.0.4/32      *[LDP/9] 00:01:52, metric 1
                    > to 10.100.23.1 via lt-0/1/0.32, label-switched-path R3-R1
10.100.0.5/32      *[LDP/9] 00:02:35, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35

mpls.0: 7 destinations, 7 routes (7 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

299824             *[LDP/9] 00:02:35, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35, Pop      
299824(S=0)        *[LDP/9] 00:02:35, metric 1
                    > to 10.100.35.2 via lt-0/1/0.35, Pop      
299840             *[LDP/9] 00:01:52, metric 1
                    > to 10.100.23.1 via lt-0/1/0.32, label-switched-path R3-R1
299856             *[LDP/9] 00:01:52, metric 1
                    > to 10.100.23.1 via lt-0/1/0.32, label-switched-path R3-R1
=====================================================================================


Thanks,
Patrick

Hi Patrick,

thanks for your feedback. It is not a question of converting the Area 1 from NSSA into a normal Area, but actually rather extending Area 0 to R3 then, and turning R3 into the ABR.

The summary is that in the first case R2 is the ABR that advertises summary LSAs for R5 and others and does not match the LSP tunnel endpoint (or any other router beyond). From the IGp metric perspective, it is actually 'closer' to R1 than R3. This is not aligned with the IGP metric calculations over the LSP that points to R3 and for that reason, you do not see FECs being propagated. In the second case, there is a clear alignement with the ABR and LSP endpoint, and for that reason FECs over the LDP tunnel are advertised and become eligible.

You have to think of LDP inherent checks still being applied on the LDP tunneling case. Herewith some further food for thought.

R3 is the endpoint for your targeted LDP session and the underlying LSP. Please bear in mind that LDP relies on the IGP for ultimate route selection (BTW, please add 'track-igp-metric' under protocols ldp at every system for proper metric tracking) and there is close alignment for IGP metrics and FECs to be actually exported and propagated.

This close alignment needs to be extended to the LDP tunneling case, so that no loops take place, for instance. Our LDP tunneling implementation relies on ’stealth shortcuts’ for this purpose, as FECs can become eligible or non-eligible upon IGP metric changes.

For this implementation, IGPs use the RSVP LSPs in their SPF computation and add hidden routes to inet.3 with RSVP-TE LSPs as next hops (you can check 'show route table inet.3 hidden') to keep them tracked. Routes are hidden because LDP is the only protocol which utilizes them and our routing tables support flash updates for all route changes and not just changes to the active route.

With this implementation, LDP is fully aware of IGP topology changes via hidden routes and if necessary become active (or inactive, should it be the case). LDP routes have better preference than IGP shortcut routes which cause the LDP routes to be installed.

Hope this helps. I would recommend you to align the ABR to be the same system as the LSP endpoint or be located 'beyond' the LDP tunnel towards destinations from the ingress system's perspective, for these FEC advertisements to become eligible.

Thanks,

Gonzalo

Thanks a lot!

Dear Gonzalo,

is there is any way to make it work without making LSP endpoint ABR? I have the same topology as a topicstarter, but I don't see any hidden routes in the inet.3 table. 

Hi v1ctor,

thanks for chiming in!

Could you please clarify your case further? Are you using the same topology or a different one? If that is the case, why would you need to extend the LDP tunnel inside the non-backbone area and not terminate it in the ABR?

Thanks,

Gonzalo

Please have a look at my topology. Every router, apart from R6 and R8, is located in the Area 0, so R4, R5 and R7 are ABRs. 

R1, R2, R6, R7, R8 and R9 are PEs, so we need routes between all of them in the inet.3

In order to connect LDP islands, we need to tunnel LDP over RSVP. There are two LSPs - r1-to-r7 and r2-to-r6. As R2 and R6 are located in different areas, LSP between them will not use CSPF. 

Just with all default settings, R9 doesn't have route to R6 in the inet.3 and vice versa. I have managed to make it work by activating LSP tunneling only over r1-to-r7 LSP, decreased to 1 it's LSP metric (IGP metric from R1 to R6 = 3), and increased OSPF metric on the links between R1<->R4 and R2<->R4 to make IGP path from R9 to R6 follow path that LSP takes. 

So the question is - is it possible to make LDP tunneling work using LSP between R2<->R6, and as it's rather academic scenario, making R6 an ABR is not an option. Thanks

Hi v1ctor,

thanks for sharing this use case and question!

The targeted LDP session can be enabled on top of any RSVP-TE LSP (with the known enablement of lo0.0 in LDP) towards a given endpoint. No matter if ABR or internal router inside an area.

It is later a question of the received LDP FECs to be eventually translated into active inet.3 routes or not, with the previous 'stealth shortcuts' and exact matching behaviors. For that purpose, the ingress LSR needs to consider that these FECs are beyond the RSVP-TE LSP endpoint as per SPF calculation results, inheriting the IGP metric.

In your area internal router case (R6), the ingress LSR detects these routes advertised from the ABR, as it does not have direct visibility on the area internal router for SPF computations and it would not work.

You may not even see hidden routes in inet.3 because of that same reason (flushing hidden routes to become active/inactive depending on IGP metrics was the mechanism selected to determine eligible FECs, but in this case there is not even a match on the LSP endpoint).

Hope this helps,

Gonzalo

PS: AFAIK, the JNCIE book scenario just covered R1->R7 (R7 is ABR), please let me know otherwise.

Thanks for thorough reply.

It's more or less clear now. 

You are welcome.

Hi.

So is there any way to make LDP Tunneling over RSVP at non ABR ? I have a problem like that, too.

R3----<LDP- Area 5>-------R1----------<Area 5>-----------<R2>---------<Area 0>-----------<R4>-------<Area1 LDP>-------R6

I already setup RSVP TE LSP between R1 and R4, they were up. But the R3 does not have FEC of R6, it seems LDP Tunneling over RSVP does not work. If I move R1 into Area 0, they will be ok.

So, is there any way to make it work without moving R1 into Area 0?

Hello,

Have You inclided lo0.0 on every router into [protocols ldp]? This is needed for LDP tunneling to work.

If yes and still no luck, please configure an OSPF Virtual Link between R1 and R2, this should make LDP tunneling to work.

HTH

Thx

Alex

So you mean, the RSVP TE LSP has to configure on ABR in case running LDP over RSVP TE ?

Hello,

---

@hoand wrote:

So you mean, the RSVP TE LSP has to configure on ABR in case running LDP over RSVP TE ?

---

I thought You did that?

If You haven't already configured RSVP on Your ABR R2 then You won't get RSVP working at all between R1 and R4.

If You want LDP tunneling to work btwn R1 and R4, configure OSPF VL between R1 and R2.

Trust me 

HTH

Thx

Alex

Hi,

is there any mean to make ldp-tunneling working without configuring ospf virtual-link?

Thanks

Paul

Hi guys

I am also testing something similar for my customer. But first want to test it in the lab and getting issue.

My topo is very basic:

PE1 --(area1)-- P1 --(area0)-- P2 --(area2)-- PE2

RSVP LSP is from PE1-PE2, and we want to run L2circuit across PEs. So we have enabled LDP on lo0 and want to tunnel it over RSVP.

The problem im getting here is that on PE1, im getting full visibility of routers loopback in LDP database,

run show ldp database logical-system PE1

Input label database, 1.1.1.1:0--4.4.4.4:0
  Label     Prefix
      0      4.4.4.4/32

Output label database, 1.1.1.1:0--4.4.4.4:0
  Label     Prefix
      0      1.1.1.1/32

(Note: PE1 is 1.1.1.1 and PE2 is 4.4.4.4)

But im not seeing its route to install in inet.3 (only RSVP route is there)

run show ldp route logical-system PE1        
Destination         Next-hop intf/lsp/table           Next-hop address
 1.1.1.1/32         lo0.1111
 2.2.2.2/32         ge-7/1/0.112                      192.168.0.5
 3.3.3.3/32         ge-7/1/0.112                      192.168.0.5
 4.4.4.4/32         ge-7/1/0.112                      192.168.0.5          -----> no lsp next-hop selected
 192.168.0.0/30     ge-7/1/0.112                      192.168.0.5
 192.168.0.4/30     ge-7/1/0.112
 192.168.0.6/32    
 192.168.0.8/30     ge-7/1/0.112                      192.168.0.5
 224.0.0.5/32      

falikhan@sydlab@MX960-mx2-re0# run show route table inet.3 logical-system PE1

inet.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

4.4.4.4/32         *[RSVP/7/1] 01:12:37, metric 3
                    > to 192.168.0.5 via ge-7/1/0.112, label-switched-path PE1-PE2

configuration is attached.

When i just made it flat area 0...it did work all OK.

So in MultiArea..is there any limitation or my configuration is wrong?

/Fahad

Attachment(s)

router config.txt   4 KB 1 version

set logical-systems R7 protocols mpls label-switched-path r7-to-r3 to 67.177.255.3
set logical-systems R7 protocols mpls label-switched-path r7-to-r3 ldp-tunneling
set logical-systems R7 protocols mpls label-switched-path r7-to-r3 inter-domain

set logical-systems R3 protocols mpls label-switched-path r3-to-r7 to 67.177.255.7
set logical-systems R3 protocols mpls label-switched-path r3-to-r7 ldp-tunneling
set logical-systems R3 protocols mpls label-switched-path r3-to-r7 inter-domain

lab@MX80-swamy# show logical-systems R5 protocols ldp

[edit]
lab@MX80-swamy#

set logical-systems R3 protocols ospf traffic-engineering
set logical-systems R3 protocols ospf area 0.0.20.82 nssa
set logical-systems R3 protocols ospf area 0.0.20.82 interface ge-1/2/9.0
set logical-systems R3 protocols ospf area 0.0.20.82 interface ge-1/3/8.0 interface-type p2p
set logical-systems R3 protocols ospf area 0.0.20.82 interface ge-1/3/2.0 interface-type p2p
set logical-systems R3 protocols ospf area 0.0.20.82 interface lo0.3

set logical-systems R7 protocols ospf traffic-engineering
set logical-systems R7 protocols ospf area 0.0.0.0 interface ge-1/0/1.1
set logical-systems R7 protocols ospf area 0.0.0.0 interface ge-1/2/9.1
set logical-systems R7 protocols ospf area 0.0.0.0 interface lo0.7
set logical-systems R7 protocols ospf area 0.0.0.0 interface ge-1/3/2.2 passive
set logical-systems R7 protocols ospf area 0.0.0.0 interface ge-1/2/6.1

lab@MX80-swamy# run show mpls lsp logical-system R7
Ingress LSP: 1 sessions
To              From            State Rt P     ActivePath       LSPname
67.177.255.3    67.177.255.7    Up     0 *                      r7-to-r3
Total 2 displayed, Up 2, Down 0

Egress LSP: 1 sessions
To              From            State   Rt Style Labelin Labelout LSPname
67.177.255.7    67.177.255.3    Up       0  1 FF       3        - r3-to-r7
Total 2 displayed, Up 2, Down 0


[edit]
lab@MX80-swamy# run show ospf route 67.177.255.7 logical-system R1    
Topology default Route Table:

Prefix             Path  Route      NH       Metric NextHop       Nexthop      
                   Type  Type       Type            Interface     Address/LSP
67.177.255.7/32    Inter Network    IP            3 ge-1/0/8.0    67.177.0.25
                                                    ge-1/2/8.0    67.177.0.30

was trying a similar scenrio, the ldp tunnel comes up between the NSSA and the router in area 0 over the RSVP tunnel when using the knob inter-domain under the -"protocols mpls label-switched-path".

After the LDP session coming up and the ldp database populated, i do find the loopback ip of NSSA router in the AREA 0 router and viceversa.

        area 0             area 20.82 (nssa)

R4----R7--------R5-----------R3----R1 (ldp)

The issue is these ldp entries in the database do not get converted into active routes in the inet.3

Still not clear how the LDP checks the database to make them valid entry in to inet.3 as an active ldp route.

It checks the IGP route and metric , but the ABR does send it.

67.177.255.3 - R3

67.177.255.5 - R5

67.177.255.7 - R7

lab@MX80-swamy# run show ospf database logical-system R7 lsa-id 67.177.255.3            

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Summary  67.177.255.3     67.177.255.5     0x80000005  1878  0x22 0xa5a0  28

lab@MX80-swamy# run show route 67.177.255.3 logical-system R7                        

inet.0: 55 destinations, 70 routes (55 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

67.177.255.3/32    *[OSPF/10] 00:04:52, metric 2
                    > to 67.177.0.6 via ge-1/2/9.1          

inet.3: 4 destinations, 4 routes (4 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

67.177.255.3/32    *[RSVP/7/1] 00:04:48, metric 2
                    > to 67.177.0.6 via ge-1/2/9.1, label-switched-path r7-to-r3

I suppose this is one of the check to be done here to understand why its failing to do so:

>>>>>>

lab@MX80-swamy# run show ospf route 67.177.255.3 logical-system R7              
Topology default Route Table:

Prefix             Path  Route      NH       Metric NextHop       Nexthop      
                   Type  Type       Type            Interface     Address/LSP
67.177.255.3/32    Inter Network    IP            2 ge-1/2/9.1    67.177.0.6

[edit]

 >>>>>>>

ITS an inter Network sent by the ABR (R5) and that is why it is not qualifying it to be an active route.

Some solution to change it to an intra route on IGP, will qualify it to be an active LDP route.

lab@MX80-swamy# rollback 1
load complete

[edit]
lab@MX80-swamy# show | compare
[edit logical-systems R3 protocols ospf area 0.0.20.82 label-switched-path r3-to-r7]
-      disable;
[edit logical-systems R7 protocols ospf area 0.0.0.0 label-switched-path r7-to-r3]
-      disable;

[edit]
lab@MX80-swamy# commit
commit complete

[edit]
lab@MX80-swamy# run show ospf route 67.177.255.3 logical-system R7   
Topology default Route Table:

Prefix             Path  Route      NH       Metric NextHop       Nexthop      
                   Type  Type       Type            Interface     Address/LSP
67.177.255.3/32    Intra Network    IP            1 r7-to-r3

>>>> this has made it to a intra route though i am not changing the R3 to be an ABR. ( no moveing the routers to different area)

and this qualifies it to be a active ldp route after this.

lab@MX80-swamy# run show route 67.177.255.3 logical-system R7                        

inet.0: 55 destinations, 70 routes (55 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

67.177.255.3/32    *[OSPF/10] 00:03:44, metric 1
                    > to 67.177.0.6 via ge-1/2/9.1, label-switched-path r7-to-r3

inet.3: 4 destinations, 5 routes (4 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

67.177.255.3/32    *[RSVP/7/1] 00:03:39, metric 1
                    > to 67.177.0.6 via ge-1/2/9.1, label-switched-path r7-to-r3
                    [LDP/9] 00:03:44, metric 1
                    > to 67.177.0.6 via ge-1/2/9.1, label-switched-path r7-to-r3

set logical-systems R7 protocols ospf area 0.0.0.0 label-switched-path r7-to-r3

set logical-systems R3 protocols ospf area 0.0.20.82 label-switched-path r3-to-r7

 ( bring up the RSVP in OSPF to make each other loopback as a type 1 and it qualifies the ldp route based on igp check)