mpls LSP on multi-area with different example of areas ospf ed isis e verifica output di funzionamento

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mpls LSP on multi-area with different example of areas ospf ed isis e verifica output di funzionamento

04.05 2020 | by massimiliano

Questo documento si prefigge di verificare con una rete di laboratorio “easy” come un LSP-MPLS si comporta rispetto a differenti […]


https://www.ingegnerianetworking.com/wp-content/uploads/2020/05/lsp-normal-area-eb3.png

Questo documento si prefigge di verificare con una rete di laboratorio “easy” come un LSP-MPLS si comporta rispetto a differenti aree OSPF e quali configurazioni e redistribuzione necessitano

 

Gli esempi seguenti evidenziano le seguenti architetture

  • – rete mpls ldp in un contesto di multi-area ospf costituita da un’area di backbone e due normal-area
  • – rete mpls ldp in un contesto di multi-area costituita da un’area di backbone e due aree Stub
  • – rete mpls ldp in un contesto di multi-area costituita da un’area di backbone e due totally Stub aree
  • – rete mpls ldp in un contesto di multi-level ISIS costituita da un Level-2 (backbone) e due Level-1 (Stub)

 

1) architettura multi-area OSPF con normal-area

 

 

 

lsp normal area

 

Esempio di configurazione

 

 

 PE1

 

 PE2
 

ip vrf PIPPO

 rd 100:100

 route-target export 100:100

 route-target import 100:100

!

mpls label protocol ldp

!

interface Loopback0

 description Lo0-IGP

 ip address 10.255.255.10 255.255.255.255

 ip ospf 1 area 0.0.0.10

!

interface Loopback100

 description Lo100-BGP

 ip address 192.168.255.10 255.255.255.255

 ip ospf 1 area 0.0.0.10

!

interface GigabitEthernet0/1

 description to-ABR1

 ip address 1.1.1.6 255.255.255.252

 ip ospf 1 area 0.0.0.10

 mpls ip

!

interface GigabitEthernet0/3

 description LAN10

 ip vrf forwarding PIPPO

 ip address 10.10.10.1 255.255.255.0

 !

router ospf 1

 router-id 10.255.255.10

!

router bgp 100

 bgp router-id 192.168.255.10

 bgp log-neighbor-changes

 no bgp default ipv4-unicast

 neighbor 192.168.255.20 remote-as 100

 neighbor 192.168.255.20 update-source Loopback100

 !

 address-family ipv4

 exit-address-family

 !

 address-family vpnv4

  neighbor 192.168.255.20 activate

  neighbor 192.168.255.20 send-community extended

 exit-address-family

 !

 address-family ipv4 vrf PIPPO

  redistribute connected

 exit-address-family

  

ip vrf PIPPO

 rd 100:100

 route-target export 100:100

 route-target import 100:100

!

mpls label protocol ldp

!

interface Loopback0

 description lo0-IGP

 ip address 10.255.255.20 255.255.255.255

 ip ospf 1 area 0.0.0.20

!

interface Loopback100

 description lo100-BGP

 ip address 192.168.255.20 255.255.255.255

 ip ospf 1 area 0.0.0.20

!

interface GigabitEthernet0/2

 description to-ABR2

 ip address 1.1.1.10 255.255.255.252

 ip ospf 1 area 0.0.0.20

mpls ip

!

interface GigabitEthernet0/3

 description LAN20

 ip vrf forwarding PIPPO

 ip address 20.20.20.1 255.255.255.0

!

router ospf 1

 router-id 10.255.255.20

!

router bgp 100

 bgp router-id 192.168.255.20

 bgp log-neighbor-changes

 no bgp default ipv4-unicast

neighbor 192.168.255.10 remote-as 100

neighbor 192.168.255.10 update-source Loopback100

 !

 address-family ipv4

 exit-address-family

 !

 address-family vpnv4

  neighbor 192.168.255.10 activate

  neighbor 192.168.255.10 send-community extended

 exit-address-family

 !

 address-family ipv4 vrf PIPPO

  redistribute connected

 exit-address-family

 

 

 

 ABR1

 

  ABR2 
 

mpls label protocol ldp

!

interface Loopback0

 description lo0-IGP

 ip address 10.255.255.1 255.255.255.255

 ip ospf 1 area 0.0.0.0

!

interface GigabitEthernet0/0

 description to-ABR2

 ip address 1.1.1.1 255.255.255.252

 ip ospf 1 area 0.0.0.0

mpls ip

!

interface GigabitEthernet0/1

 description to-PE1

 ip address 1.1.1.5 255.255.255.252

 ip ospf 1 area 0.0.0.10

 mpls ip

!

router ospf 1

 router-id 10.255.255.1

!

  

mpls label protocol ldp

!

interface Loopback0

 description Lo0-IGP

 ip address 10.255.255.2 255.255.255.255

 ip ospf 1 area 0.0.0.0

!

interface GigabitEthernet0/0

 description to-ABR1

 ip address 1.1.1.2 255.255.255.252

 ip ospf 1 area 0.0.0.0

 mpls ip

!

interface GigabitEthernet0/2

 description to-PE2

 ip address 1.1.1.9 255.255.255.252

 ip ospf 1 area 0.0.0.20

 mpls ip

!

router ospf 1

 router-id 10.255.255.2

!

 

 

lsp direz traff es1

 

 TEST di Raggiungibilità PC1 to PC2 (Direzione del traffico from PE1 to PE2)

 

PC1> ping 20.20.20.20

84 bytes from 20.20.20.20 icmp_seq=1 ttl=60 time=9.966 ms

84 bytes from 20.20.20.20 icmp_seq=2 ttl=60 time=5.545 ms

84 bytes from 20.20.20.20 icmp_seq=3 ttl=60 time=6.225 ms

^C

PC1> trace 20.20.20.20

trace to 20.20.20.20, 8 hops max, press Ctrl+C to stop

 1   10.10.10.1   1.768 ms  1.854 ms  1.380 ms

 2   1.1.1.5   5.863 ms  5.714 ms  5.192 ms

 3   1.1.1.2   5.191 ms  5.891 ms  5.283 ms

 4   20.20.20.1   6.533 ms  6.261 ms  5.071 ms

 5   *20.20.20.20   5.333 ms (ICMP type:3, code:3, Destination port unreachable)

 

 

PE1#traceroute vrf PIPPO 20.20.20.20

Type escape sequence to abort.

Tracing the route to 20.20.20.20

VRF info: (vrf in name/id, vrf out name/id)

  1 1.1.1.5 [MPLS: Labels 20/22 Exp 0] 6 msec 9 msec 6 msec

  2 1.1.1.2 [MPLS: Labels 20/22 Exp 0] 7 msec 6 msec 6 msec

  3 20.20.20.1 7 msec 8 msec 8 msec

  4  *

    20.20.20.20 8 msec 6 msec

  

 

PE1#show ip bgp vpnv4 vrf PIPPO 20.20.20.20

BGP routing table entry for 100:100:20.20.20.0/24, version 4

Paths: (1 available, best #1, table PIPPO)

  Not advertised to any peer

  Refresh Epoch 1

  Local

    192.168.255.20 (metric 4) (via default) from 192.168.255.20 (192.168.255.20)

      Origin incomplete, metric 0, localpref 100, valid, internal, best

      Extended Community: RT:100:100

      mpls labels in/out nolabel/22

      rx pathid: 0, tx pathid: 0x0

 

PE1#show ip route 192.168.255.20

Routing entry for 192.168.255.20/32

  Known via “ospf 1”, distance 110, metric 4, type inter area

  Last update from 1.1.1.5 on GigabitEthernet0/1, 00:38:21 ago

  Routing Descriptor Blocks:

  * 1.1.1.5, from 10.255.255.1, 00:38:21 ago, via GigabitEthernet0/1

      Route metric is 4, traffic share count is 1

 

 

From PE2

 

PE2#show ip bgp vpnv4 vrf PIPPO 20.20.20.20

BGP routing table entry for 100:100:20.20.20.0/24, version 2

Paths: (1 available, best #1, table PIPPO)

  Advertised to update-groups:

     1

  Refresh Epoch 1

  Local

    0.0.0.0 (via vrf PIPPO) from 0.0.0.0 (192.168.255.20)

      Origin incomplete, metric 0, localpref 100, weight 32768, valid, sourced, best

      Extended Community: RT:100:100

      mpls labels in/out 22/nolabel(PIPPO)

      rx pathid: 0, tx pathid: 0x0

 

 

 

Verifica MPLS LDP:

 

  Verifica MPLS forwarding table:
 

PE1#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.1:0; Local LDP Ident 10.255.255.10:0

        TCP connection: 10.255.255.1.646 – 10.255.255.10.23396

        State: Oper; Msgs sent/rcvd: 93/95; Downstream

        Up time: 01:11:22

        LDP discovery sources:

          GigabitEthernet0/1, Src IP addr: 1.1.1.5

        Addresses bound to peer LDP Ident:

          1.1.1.1         1.1.1.5         10.255.255.1

 

 

ABR1#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.10:0; Local LDP Ident 10.255.255.1:0

        TCP connection: 10.255.255.10.23396 – 10.255.255.1.646

        State: Oper; Msgs sent/rcvd: 97/95; Downstream

        Up time: 01:12:45

        LDP discovery sources:

          GigabitEthernet0/1, Src IP addr: 1.1.1.6

        Addresses bound to peer LDP Ident:

          1.1.1.6         10.255.255.10   192.168.255.10

   

    Peer LDP Ident: 10.255.255.2:0; Local LDP Ident 10.255.255.1:0

        TCP connection: 10.255.255.2.15569 – 10.255.255.1.646

        State: Oper; Msgs sent/rcvd: 85/88; Downstream

        Up time: 01:05:29

        LDP discovery sources:

          GigabitEthernet0/0, Src IP addr: 1.1.1.2

        Addresses bound to peer LDP Ident:

          1.1.1.2         10.255.255.2    1.1.1.9

 

 

ABR2#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.1:0; Local LDP Ident 10.255.255.2:0

        TCP connection: 10.255.255.1.646 – 10.255.255.2.15569

        State: Oper; Msgs sent/rcvd: 92/89; Downstream

        Up time: 01:09:16

        LDP discovery sources:

          GigabitEthernet0/0, Src IP addr: 1.1.1.1

        Addresses bound to peer LDP Ident:

          1.1.1.1         1.1.1.5         10.255.255.1

   

    Peer LDP Ident: 192.168.255.20:0; Local LDP Ident 10.255.255.2:0

        TCP connection: 192.168.255.20.53091 – 10.255.255.2.646

        State: Oper; Msgs sent/rcvd: 66/67; Downstream

        Up time: 00:48:09

        LDP discovery sources:

          GigabitEthernet0/2, Src IP addr: 1.1.1.10

        Addresses bound to peer LDP Ident:

          1.1.1.10        10.255.255.20   192.168.255.20

 

 

PE2#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.2:0; Local LDP Ident 192.168.255.20:0

        TCP connection: 10.255.255.2.646 – 192.168.255.20.53091

        State: Oper; Msgs sent/rcvd: 70/69; Downstream

        Up time: 00:50:08

        LDP discovery sources:

          GigabitEthernet0/2, Src IP addr: 1.1.1.9

        Addresses bound to peer LDP Ident:

          1.1.1.2         10.255.255.2    1.1.1.9

 

PE1#show mpls forwarding-table

 

Local      Outgoing      Prefix                           Bytes Label   Outgoing   Next Hop

Label      Label           or Tunnel Id                  Switched        interface

16           Pop Label    10.255.255.1/32           0                   Gi0/1           1.1.1.5

17           Pop Label    1.1.1.0/30                     0                   Gi0/1           1.1.1.5

18           18                10.255.255.2/32           0                   Gi0/1           1.1.1.5

19           19                1.1.1.8/30                     0                   Gi0/1           1.1.1.5

20           20                192.168.255.20/32       0                   Gi0/1           1.1.1.5

21           21                10.255.255.20/32         0                   Gi0/1           1.1.1.5

22           No Label     10.10.10.0/24[V]          1536              aggregate/PIPPO

 

 

 

ABR1#show mpls forwarding-table

 

Local      Outgoing       Prefix                         Bytes Label   Outgoing   Next Hop

Label      Label            or Tunnel Id                 Switched        interface

16           Pop Label    192.168.255.10/32       4374             Gi0/1            1.1.1.6

17           Pop Label    10.255.255.10/32         0                   Gi0/1            1.1.1.6

18           Pop Label    10.255.255.2/32           0                   Gi0/0            1.1.1.2

19           Pop Label    1.1.1.8/30                     0                   Gi0/0            1.1.1.2

20           20                192.168.255.20/32      3461              Gi0/0            1.1.1.2

21           21                10.255.255.20/32        0                    Gi0/0            1.1.1.2

 

 

 

ABR2#show mpls forwarding-table

 

Local      Outgoing      Prefix                       Bytes Label     Outgoing   Next Hop

Label      Label            or Tunnel Id                Switched      interface

16           Pop Label     1.1.1.4/30                   0                 Gi0/0      1.1.1.1

17           Pop Label     10.255.255.1/32         0                 Gi0/0      1.1.1.1

18           17                 10.255.255.10/32       0                 Gi0/0      1.1.1.1

19           16                 192.168.255.10/32     5315           Gi0/0      1.1.1.1

20          Pop Label     192.168.255.20/32     4258          Gi0/2       1.1.1.10

21          Pop Label     10.255.255.20/32     0                   Gi0/2       1.1.1.10

 

 

 

PE2#show mpls forwarding-table

 

Local      Outgoing        Prefix                        Bytes Label      Outgoing   Next Hop

Label      Label             or Tunnel Id                Switched          interface

16          19                   192.168.255.10/32       0                    Gi0/2       1.1.1.9

17          18                   10.255.255.10/32         0                    Gi0/2       1.1.1.9

18          Pop Label       10.255.255.2/32           0                    Gi0/2       1.1.1.9

19          17                   10.255.255.1/32           0                    Gi0/2      1.1.1.9

20          16                   1.1.1.4/30                     0                    Gi0/2      1.1.1.9

21          Pop Label       1.1.1.0/30                     0                    Gi0/2      1.1.1.9

22          No Label        20.20.20.0/24[V]          1416               aggregate/PIPPO

 

 

Visione d’insieme grafica:

 

lsp ospf es1

 

Si ricorda che in una architettura multi-area tra backbone e normal-area abbiamo questa situazione:

 

lsa backbone area

 

 

2) architettura multi-area OSPF con STUB-area

 

Con una STUB area i tipi di LSA che sono permesse sono:

LSA type 1

LSA type 2

LSA type 3 summary

ed inoltre la default-route verso il nodo interno all’area stub

 

 

lsa stub ospf 

 

E difatti anche in questo scenario ritroviamo le stesse condizioni medesime viste in precedenza per la condizione di mpls forwarding-table e per il database ospf.

La differenza la troviamo solo a livello di area stub che a differenza di prima riceve anche una default route:

 

PE1#show ip route

Gateway of last resort is 1.1.1.5 to network 0.0.0.0

O*IA  0.0.0.0/0 [110/2] via 1.1.1.5, 00:10:02, GigabitEthernet0/1

      1.0.0.0/8 is variably subnetted, 4 subnets, 2 masks

 

PE1#show ip bgp vpnv4 vrf PIPPO 20.20.20.20

BGP routing table entry for 100:100:20.20.20.0/24, version 3

Paths: (1 available, best #1, table PIPPO)

  Not advertised to any peer

  Refresh Epoch 1

  Local

    192.168.255.20 (metric 4) (via default) from 192.168.255.20 (192.168.255.20)

      Origin incomplete, metric 0, localpref 100, valid, internal, best

      Extended Community: RT:100:100

      mpls labels in/out nolabel/22

      rx pathid: 0, tx pathid: 0x0

 

 

PE1#show mpls forwarding-table

Local      Outgoing   Prefix                        Bytes Label   Outgoing   Next Hop

Label      Label      or Tunnel Id                 Switched      interface

16           Pop Label  10.255.255.1/32          0             Gi0/1      1.1.1.5

17           Pop Label  1.1.1.0/30                    0             Gi0/1      1.1.1.5

18           18         10.255.255.2/32               0             Gi0/1      1.1.1.5

19           19         1.1.1.8/30                         0             Gi0/1      1.1.1.5

20           20         192.168.255.20/32           0             Gi0/1      1.1.1.5

21           21         10.255.255.20/32             0             Gi0/1      1.1.1.5

23         No Label   10.10.10.0/24[V]            0             aggregate/PIPPO

 

 

 

ABR1#show ip ospf database summary 192.168.255.20

            OSPF Router with ID (10.255.255.1) (Process ID 1)

                Summary Net Link States (Area 0.0.0.0)

  LS age: 1222

  Options: (No TOS-capability, DC, Upward)

  LS Type: Summary Links(Network)

  Link State ID: 192.168.255.20 (summary Network Number)

  Advertising Router: 10.255.255.2

  LS Seq Number: 80000002

  Checksum: 0xBAF5

  Length: 28

  Network Mask: /32

        MTID: 0         Metric: 2

                Summary Net Link States (Area 0.0.0.10)

  LS age: 1678

  Options: (No TOS-capability, DC, Upward)

  LS Type: Summary Links(Network)

  Link State ID: 192.168.255.20 (summary Network Number)

  Advertising Router: 10.255.255.1

  LS Seq Number: 80000002

  Checksum: 0xE8C9

  Length: 28

  Network Mask: /32

        MTID: 0         Metric: 3

 

 

PE1#traceroute vrf PIPPO 20.20.20.20

Type escape sequence to abort.

Tracing the route to 20.20.20.20

VRF info: (vrf in name/id, vrf out name/id)

  1 1.1.1.5 [MPLS: Labels 20/22 Exp 0] 6 msec 5 msec 5 msec

  2 1.1.1.2 [MPLS: Labels 20/22 Exp 0] 6 msec 5 msec 5 msec

  3 20.20.20.1 6 msec 6 msec 8 msec

  4 20.20.20.20 11 msec 5 msec 6 msec

 

 

3) architettura multi-area OSPF con Totally STUB-area

 

In questo caso ci troviamo in una situazione dove abbiamo questo tipo di LSA permesse:

LSA type 1

LSA type 2

default route

 

totally stub lsa ospf 

 

E la situazione per la parte MPLS-LSP cambia.

 

PE1#traceroute vrf PIPPO 20.20.20.20

Type escape sequence to abort.

Tracing the route to 20.20.20.20

VRF info: (vrf in name/id, vrf out name/id)

  1  *  *  *

  2  *  *  *

  3  *  *  *

  4  *  *  *

PC1> ping 20.20.20.20

20.20.20.20 icmp_seq=1 timeout

20.20.20.20 icmp_seq=2 timeout

20.20.20.20 icmp_seq=3 timeout

20.20.20.20 icmp_seq=4 timeout

20.20.20.20 icmp_seq=5 timeout

PC1> trace 20.20.20.20

trace to 20.20.20.20, 8 hops max, press Ctrl+C to stop

 1   10.10.10.1   3.338 ms  2.153 ms  3.234 ms

 2     *  *  *

 3     *  *  *

 4     *  *  *

 5     *  *  *

 6     *  *  *

 7     *  *  *

 8     *   

 

PE1#show mpls forwarding-table

Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop

Label      Label      or Tunnel Id     Switched      interface

23         No Label   10.10.10.0/24[V] 1536          aggregate/PIPPO

 

PE1#show ip route

Gateway of last resort is 1.1.1.5 to network 0.0.0.0

O*IA  0.0.0.0/0 [110/2] via 1.1.1.5, 00:12:08, GigabitEthernet0/1

      1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        1.1.1.4/30 is directly connected, GigabitEthernet0/1

L        1.1.1.6/32 is directly connected, GigabitEthernet0/1

      10.0.0.0/32 is subnetted, 1 subnets

C        10.255.255.10 is directly connected, Loopback0

      192.168.255.0/32 is subnetted, 1 subnets

C        192.168.255.10 is directly connected, Loopback100

 

 

ABR1#show ip ospf database summary 192.168.255.20

            OSPF Router with ID (10.255.255.1) (Process ID 1)

                Summary Net Link States (Area 0.0.0.0)

  LS age: 719

  Options: (No TOS-capability, DC, Upward)

  LS Type: Summary Links(Network)

  Link State ID: 192.168.255.20 (summary Network Number)

  Advertising Router: 10.255.255.2

  LS Seq Number: 80000001

  Checksum: 0xBCF4

  Length: 28

  Network Mask: /32

        MTID: 0         Metric: 2

 

Non è presente in area 0.0.0.10

 

Il path LSP end-to-end si interrompe.

 

Quindi NON FUNZIONA... ed a questo punto… o quando progettiamo una rete LSP-MPLS lasciamo perdere aree ospf di tipo Totally-Stub oppure….

Questa stessa architettura è paragonabile ad una architettura con ISIS dove abbiamo un Level 2 visto come area backbone e due Level 1 viste come aree differenti (Stub) adiacenti all’area di backbone [ troviamo questa situazione spesso in una architettura di tipo ” seamless mpls ” ]

 

 

lsp isis es1

si riportano le configurazioni per maggiori dettagli:

 

 

 PE3 with ISIS

 

  PE4 with ISIS

router isis

 net 49.0001.0000.0000.0010.00

 passive-interface default

 no passive-interface GigabitEthernet0/1

!

interface GigabitEthernet0/1

 description to-ABR1

 ip address 1.1.1.6 255.255.255.252

 ip router isis

 mpls ip

 isis circuit-type level-1

 isis network point-to-point

!

 

PE3#show isis neighbors

Tag null:

System Id       Type Interface     IP Address      State Holdtime Circuit Id

ABR3               L1   Gi0/1         1.1.1.5               UP    21       00

 

 

 

 

router isis

 net 49.0001.0000.0000.0020.00

 passive-interface default

 no passive-interface GigabitEthernet0/2

!

interface GigabitEthernet0/2

 description to-ABR2

 ip address 1.1.1.10 255.255.255.252

 ip router isis

 mpls ip

 isis circuit-type level-1

 isis network point-to-point

!

 

PE4#show isis neighbors

Tag null:

System Id       Type Interface     IP Address      State Holdtime Circuit Id

ABR4               L1   Gi0/2         1.1.1.9               UP    22       01

 

 

 

 ABR3 with ISIS

 

  ABR4 with ISIS
 

router isis

 net 49.0001.0000.0000.0001.00

 passive-interface default

 no passive-interface GigabitEthernet0/0

 no passive-interface GigabitEthernet0/1

!

interface GigabitEthernet0/0

 description to-ABR2

 ip address 1.1.1.1 255.255.255.252

 ip router isis

 duplex auto

 speed auto

 media-type rj45

 mpls ip

 isis circuit-type level-2-only

 isis network point-to-point

!

interface GigabitEthernet0/1

 description to-PE1

 ip address 1.1.1.5 255.255.255.252

 ip router isis

 duplex auto

 speed auto

 media-type rj45

 mpls ip

 isis circuit-type level-1

 isis network point-to-point

!

ABR3#show isis neighbors

System Id       Type Interface     IP Address      State Holdtime Circuit Id

ABR4              L2   Gi0/0         1.1.1.2               UP    25       00

PE3                 L1   Gi0/1         1.1.1.6               UP    27       00

 

 

  

router isis

 net 49.0001.0000.0000.0002.00

 passive-interface default

 no passive-interface GigabitEthernet0/0

 no passive-interface GigabitEthernet0/2

!

interface GigabitEthernet0/0

 description to-ABR1

 ip address 1.1.1.2 255.255.255.252

 ip router isis

 duplex auto

 speed auto

 media-type rj45

 mpls ip

 isis circuit-type level-2-only

 isis network point-to-point

!

interface GigabitEthernet0/2

 description to-PE2

 ip address 1.1.1.9 255.255.255.252

 ip router isis

 duplex auto

 speed auto

 media-type rj45

 mpls ip

 isis circuit-type level-1

 isis network point-to-point

!

ABR4#show isis neighbors

System Id       Type Interface     IP Address      State Holdtime Circuit Id

ABR3              L2   Gi0/0         1.1.1.1                UP    27       01

PE4                 L1   Gi0/2         1.1.1.10              UP    29       00

 

 

Vediamo ora di verificare gli output in termini MPLS:

Le adiacenze LDP restano corrette:

 

PE3#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.1:0; Local LDP Ident 192.168.255.10:0

        TCP connection: 10.255.255.1.646 – 192.168.255.10.21182

        State: Oper; Msgs sent/rcvd: 58/63; Downstream

        Up time: 00:45:17

        LDP discovery sources:

          GigabitEthernet0/1, Src IP addr: 1.1.1.5

        Addresses bound to peer LDP Ident:

          1.1.1.1         1.1.1.5         10.255.255.1

 

ABR3#show mpls ldp neighbor

    Peer LDP Ident: 192.168.255.10:0; Local LDP Ident 10.255.255.1:0

        TCP connection: 192.168.255.10.21182 – 10.255.255.1.646

        State: Oper; Msgs sent/rcvd: 63/58; Downstream

        Up time: 00:45:31

        LDP discovery sources:

          GigabitEthernet0/1, Src IP addr: 1.1.1.6

        Addresses bound to peer LDP Ident:

          1.1.1.6         10.255.255.10   192.168.255.10

    Peer LDP Ident: 10.255.255.2:0; Local LDP Ident 10.255.255.1:0

        TCP connection: 10.255.255.2.62961 – 10.255.255.1.646

        State: Oper; Msgs sent/rcvd: 59/61; Downstream

        Up time: 00:42:22

        LDP discovery sources:

          GigabitEthernet0/0, Src IP addr: 1.1.1.2

        Addresses bound to peer LDP Ident:

          1.1.1.2         10.255.255.2    1.1.1.9

 

ABR4#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.1:0; Local LDP Ident 10.255.255.2:0

        TCP connection: 10.255.255.1.646 – 10.255.255.2.62961

        State: Oper; Msgs sent/rcvd: 66/64; Downstream

        Up time: 00:46:08

        LDP discovery sources:

          GigabitEthernet0/0, Src IP addr: 1.1.1.1

        Addresses bound to peer LDP Ident:

          1.1.1.1         1.1.1.5         10.255.255.1

    Peer LDP Ident: 192.168.255.20:0; Local LDP Ident 10.255.255.2:0

        TCP connection: 192.168.255.20.34969 – 10.255.255.2.646

        State: Oper; Msgs sent/rcvd: 61/57; Downstream

        Up time: 00:43:19

        LDP discovery sources:

          GigabitEthernet0/2, Src IP addr: 1.1.1.10

        Addresses bound to peer LDP Ident:

          1.1.1.10        10.255.255.20   192.168.255.20

 

PE4#show mpls ldp neighbor

    Peer LDP Ident: 10.255.255.2:0; Local LDP Ident 192.168.255.20:0

        TCP connection: 10.255.255.2.646 – 192.168.255.20.34969

        State: Oper; Msgs sent/rcvd: 58/62; Downstream

        Up time: 00:44:18

        LDP discovery sources:

          GigabitEthernet0/2, Src IP addr: 1.1.1.9

        Addresses bound to peer LDP Ident:

          1.1.1.2         10.255.255.2    1.1.1.9

 

Ma le differenze le troviamo nella tabella di forwarding mpls:

 

 show mpls forwarding table (in situazione normale)  show mpls forwarding table (con totally stub aree/level)
 

PE1#show mpls forwarding-table

 

Local      Outgoing      Prefix                           Bytes Label   Outgoing   Next Hop

Label      Label           or Tunnel Id                  Switched        interface

16           Pop Label    10.255.255.1/32           0                   Gi0/1           1.1.1.5

17           Pop Label    1.1.1.0/30                     0                   Gi0/1           1.1.1.5

18           18                10.255.255.2/32           0                   Gi0/1           1.1.1.5

19           19                1.1.1.8/30                     0                   Gi0/1           1.1.1.5

20           20                192.168.255.20/32       0                   Gi0/1           1.1.1.5

21           21                10.255.255.20/32         0                   Gi0/1           1.1.1.5

22           No Label     10.10.10.0/24[V]          1536              aggregate/PIPPO

 

 

 

ABR1#show mpls forwarding-table

 

Local      Outgoing       Prefix                         Bytes Label   Outgoing   Next Hop

Label      Label            or Tunnel Id                 Switched        interface

16           Pop Label    192.168.255.10/32       4374             Gi0/1            1.1.1.6

17           Pop Label    10.255.255.10/32         0                   Gi0/1            1.1.1.6

18           Pop Label    10.255.255.2/32           0                   Gi0/0            1.1.1.2

19           Pop Label    1.1.1.8/30                     0                   Gi0/0            1.1.1.2

20           20                192.168.255.20/32      3461              Gi0/0            1.1.1.2

21           21                10.255.255.20/32        0                    Gi0/0            1.1.1.2

 

 

 

ABR2#show mpls forwarding-table

 

Local      Outgoing      Prefix                       Bytes Label     Outgoing   Next Hop

Label      Label            or Tunnel Id                Switched      interface

16           Pop Label     1.1.1.4/30                   0                 Gi0/0      1.1.1.1

17           Pop Label     10.255.255.1/32         0                 Gi0/0      1.1.1.1

18           17                 10.255.255.10/32       0                 Gi0/0      1.1.1.1

19           16                 192.168.255.10/32     5315           Gi0/0      1.1.1.1

20          Pop Label     192.168.255.20/32     4258          Gi0/2       1.1.1.10

21          Pop Label     10.255.255.20/32     0                   Gi0/2       1.1.1.10

 

 

 

PE2#show mpls forwarding-table

 

Local      Outgoing        Prefix                        Bytes Label      Outgoing   Next Hop

Label      Label             or Tunnel Id                Switched          interface

16          19                   192.168.255.10/32       0                    Gi0/2       1.1.1.9

17          18                   10.255.255.10/32         0                    Gi0/2       1.1.1.9

18          Pop Label       10.255.255.2/32           0                    Gi0/2       1.1.1.9

19          17                   10.255.255.1/32           0                    Gi0/2      1.1.1.9

20          16                   1.1.1.4/30                     0                    Gi0/2      1.1.1.9

21          Pop Label       1.1.1.0/30                     0                    Gi0/2      1.1.1.9

22          No Label        20.20.20.0/24[V]          1416               aggregate/PIPPO

  

PE3#show mpls forwarding-table

Local      Outgoing            Prefix                       Bytes Label   Outgoing   Next Hop

Label      Label                  or Tunnel Id              Switched      interface

16           No Label            10.10.10.0/24[V]       0                   aggregate/PIPPO

17           Pop Label          10.255.255.1/32        0                  Gi0/1      1.1.1.5

 

NOTA: manca l’indirizzo NH 192.168.255.20

 

 

ABR3#show mpls forwarding-table

Local      Outgoing         Prefix                             Bytes Label   Outgoing   Next Hop

Label      Label               or Tunnel Id                   Switched      interface

16           Pop Label      10.255.255.10/32           0                   Gi0/1      1.1.1.6

17           Pop Label      192.168.255.10/32         0                   Gi0/1      1.1.1.6

18           Pop Label      10.255.255.2/32             0                   Gi0/0      1.1.1.2

19           Pop Label      1.1.1.8/30                       0                   Gi0/0      1.1.1.2

20           20                  10.255.255.20/32           0                  Gi0/0      1.1.1.2

21           21                  192.168.255.20/32         0                  Gi0/0      1.1.1.2

 

 

ABR4#show mpls forwarding-table

Local      Outgoing           Prefix                  Bytes Label   Outgoing   Next Hop

Label      Label                 or Tunnel Id       Switched      interface

16           Pop Label         1.1.1.4/30                 0                 Gi0/0      1.1.1.1

17           Pop Label         10.255.255.1/32       0                 Gi0/0      1.1.1.1

18           16                     10.255.255.10/32     0                Gi0/0      1.1.1.1

19           17                     192.168.255.10/32   0                 Gi0/0      1.1.1.1

20         Pop Label            10.255.255.20/32    0                  Gi0/2      1.1.1.10

21         Pop Label            192.168.255.20/32   0                Gi0/2      1.1.1.10

 

 

 

PE4#show mpls forwarding-table

Local      Outgoing       Prefix                   Bytes Label   Outgoing   Next Hop

Label      Label            or Tunnel Id           Switched      interface

16           No Label      20.20.20.0/24[V]     0                 aggregate/PIPPO

17           Pop Label    10.255.255.2/32      0                 Gi0/2      1.1.1.9

 

 

E’ evidente come gli ABR svolgono un ruolo fondamentale per la redistribuzione del corretto Next-Hop (nel nostro caso l’indirizzo 192.168.255.20) per la raggiungibilià della rete target.

La soluzione è quella di permettere una redistribuzione delle loopback operata a livello ABR dal Level-2 to Level-1 secondo questa configurazione:

 

 

 ABR3 with ISIS

 

  ABR4 with ISIS
 

router isis

 net 49.0001.0000.0000.0001.00

 metric-style wide

 redistribute isis ip level-2 into level-1 route-map L2-L1

 passive-interface default

 no passive-interface GigabitEthernet0/0

 no passive-interface GigabitEthernet0/1

!

route-map L2-L1 permit 10

 match ip address 10

!

access-list 10 permit 192.168.255.20

 

  

router isis

 net 49.0001.0000.0000.0002.00

 metric-style wide

 redistribute isis ip level-2 into level-1 route-map L2-L1

 passive-interface default

 no passive-interface GigabitEthernet0/0

 no passive-interface GigabitEthernet0/2

!

route-map L2-L1 permit 10

 match ip address 10

!

access-list 10 permit 192.168.255.10

 

A seguito di questa configurazione abbiamo quindi:

 

 

PE3#

*May  5 13:59:23.274: %BGP-5-ADJCHANGE: neighbor 192.168.255.20 Up

 

PE4#

*May  5 13:59:24.848: %BGP-5-ADJCHANGE: neighbor 192.168.255.10 Up

 

Andiamo a vedere le rispettive tabelle di routing a livello PE (lato interno delle aree/livelli):

 

PE3#show ip route

Gateway of last resort is not set

      1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        1.1.1.4/30 is directly connected, GigabitEthernet0/1

L        1.1.1.6/32 is directly connected, GigabitEthernet0/1

      10.0.0.0/32 is subnetted, 2 subnets

i L1     10.255.255.1 [115/10] via 1.1.1.5, 01:04:38, GigabitEthernet0/1

C        10.255.255.10 is directly connected, Loopback0

      192.168.255.0/32 is subnetted, 2 subnets

C        192.168.255.10 is directly connected, Loopback100

i ia     192.168.255.20 [115/30] via 1.1.1.5, 00:07:15, GigabitEthernet0/1

 

 

PE4#show ip route

Gateway of last resort is not set

      1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        1.1.1.8/30 is directly connected, GigabitEthernet0/2

L        1.1.1.10/32 is directly connected, GigabitEthernet0/2

      10.0.0.0/32 is subnetted, 2 subnets

i L1     10.255.255.2 [115/10] via 1.1.1.9, 01:05:11, GigabitEthernet0/2

C        10.255.255.20 is directly connected, Loopback0

      192.168.255.0/32 is subnetted, 2 subnets

i ia     192.168.255.10 [115/30] via 1.1.1.9, 00:07:33, GigabitEthernet0/2

C        192.168.255.20 is directly connected, Loopback100

 

 

Verifichiamo la parte MPLS:

 

 

PE3#show mpls forwarding-table

Local      Outgoing        Prefix                        Bytes Label   Outgoing   Next Hop

Label      Label             or Tunnel Id               Switched      interface

17           No Label       10.10.10.0/24[V]        0                  aggregate/PIPPO

18           Pop Label     10.255.255.1/32        0                   Gi0/1      1.1.1.5

20           23                 192.168.255.20/32    0                   Gi0/1      1.1.1.5

 

 

 

PE4#show mpls forwarding-table

Local      Outgoing      Prefix                            Bytes Label   Outgoing   Next Hop

Label      Label           or Tunnel Id                     Switched      interface

17           No Label     20.20.20.0/24[V]                 0               aggregate/PIPPO

18           Pop Label   10.255.255.2/32                 0                Gi0/2      1.1.1.9

20           23               192.168.255.10/32             0                Gi0/2      1.1.1.9

 

 

E verifichiamola con il BGP:

 

PE3#show ip bgp vpnv4 vrf PIPPO 20.20.20.20

BGP routing table entry for 100:100:20.20.20.0/24, version 6

Paths: (1 available, best #1, table PIPPO)

  Not advertised to any peer

  Refresh Epoch 1

  Local

    192.168.255.20 (metric 30) (via default) from 192.168.255.20 (192.168.255.20)

      Origin incomplete, metric 0, localpref 100, valid, internal, best

      Extended Community: RT:100:100

      mpls labels in/out nolabel/17

      rx pathid: 0, tx pathid: 0x0

 

 

PE3#traceroute vrf PIPPO 20.20.20.20

Type escape sequence to abort.

Tracing the route to 20.20.20.20

VRF info: (vrf in name/id, vrf out name/id)

  1 1.1.1.5 [MPLS: Labels 23/17 Exp 0] 6 msec 6 msec 7 msec

  2 1.1.1.2 [MPLS: Labels 18/17 Exp 0] 5 msec 6 msec 6 msec

  3 20.20.20.1 6 msec 5 msec 6 msec

  4 20.20.20.20 6 msec 5 msec 5 msec

 

 

ABR3#show mpls forwarding-table

Local      Outgoing       Prefix                         Bytes Label   Outgoing   Next Hop

Label      Label            or Tunnel Id                 Switched      interface

16           Pop Label    10.255.255.10/32         0                   Gi0/1      1.1.1.6

17           Pop Label    192.168.255.10/32       9031             Gi0/1      1.1.1.6

18           Pop Label    10.255.255.2/32          0                    Gi0/0      1.1.1.2

20           19                10.255.255.20/32        0                    Gi0/0      1.1.1.2

21            Pop Label   1.1.1.8/30                    0                    Gi0/0      1.1.1.2

23           18                192.168.255.20/32      6925              Gi0/0      1.1.1.2

 

 

ABR4#show mpls forwarding-table

Local      Outgoing        Prefix                             Bytes Label   Outgoing   Next Hop

Label      Label             or Tunnel Id                      Switched      interface

16           Pop Label    1.1.1.4/30                       0                      Gi0/0      1.1.1.1

17           Pop Label    10.255.255.1/32             0                      Gi0/0      1.1.1.1

18           Pop Label    192.168.255.20/32        7512                 Gi0/2      1.1.1.10

19           Pop Label    10.255.255.20/32          0                       Gi0/2      1.1.1.10

22           16                10.255.255.10/32          0                       Gi0/0      1.1.1.1

23           17                 192.168.255.10/32       9954          Gi0/0      1.1.1.1

 

 

Da un punto di vista grafico abbiamo:

 

lsp isis es2

 

PC3> ping 20.20.20.20

84 bytes from 20.20.20.20 icmp_seq=1 ttl=60 time=5.316 ms

84 bytes from 20.20.20.20 icmp_seq=2 ttl=60 time=4.807 ms

84 bytes from 20.20.20.20 icmp_seq=3 ttl=60 time=7.663 ms

^C

PC3>

PC3> trace 20.20.20.20

trace to 20.20.20.20, 8 hops max, press Ctrl+C to stop

 1   10.10.10.1   2.452 ms  1.625 ms  1.920 ms

 2   1.1.1.5   6.111 ms  5.650 ms  5.077 ms

 3   1.1.1.2   8.015 ms  5.944 ms  6.367 ms

 4   20.20.20.1   6.111 ms  6.968 ms  7.420 ms

 5     *  *  *

 6   *20.20.20.20   6.638 ms (ICMP type:3, code:3, Destination port unreachable)

 

 

Ora Funziona.

🙂

 

 

 

 

 

 

 

 

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