Many times we came across terms like, L2VPN (layer 2 vpn), In this section we will see how to configure L2 VPN in MPLS for Maipu Routers. It’s a service which a service provider offers to customer. SP provide end to end L2 VPN over own MPLS cloud.
So that customer can use own IP addresses and customer will feel that they have dedicated Point to Point link from one site to another site. L2 vpn is emulating legacy costly point to point links.
Since these are configured on shared media, that’s why the cost will be cheap than dedicated point to point connection from Telco.
Here is a MPLS topology and two different customers VPN sites.
Topology
MPLS L2VPN Network diagram
Description of Topology
In the configuration instance, router 1 and router 3 are PE devices; router 2 is the P device; the P and PE devices form the MPLS backbone network. Here, router 1 and router 2 are connected via the serial port; router 2 and router 3 are connected via Ethernet interface. In the MPLS backbone network, run the IGP routing protocol and label distributing protocol LDP.
The MPLS network is connected to two different VPN users (VPN A and VPN B). The MPLS network adopts the LDP to distribute the L2VPN virtual circuit labels to realize the intercommunication between VPN A/Site1 connected to router 1 and VPN A/Site2 connected to router 3 (corresponding to VPN A), as well as the intercommunication between VPN B/Site1 connected to router 1 and VPN B/Site2 connected to router 3 (corresponding to VPN B).
Configuration Template -
The configuration of router 1:
| Command | Description |
| Router1(config)# mpls ip | Enable the global MPLS label forwarding |
| Router1(config)# interface loopback0 | Configure the loopback port (IP address is 1.1.1.1) |
| Router1 (config-if-loopback0)# ip address 1.1.1.1 255.255.255.255 |
|
| Router1 (config-if-loopback0)# exit |
|
| Router1 (config)# interface fastethernet 0 | Configure f0 |
| Router1 (config-if-fastethernet0)# mpls ip | Configure mpls ip |
| Router1 (config-if-fastethernet0)# xconnect 3.3.3.3 100 encapsulation mpls | Configure f0to encapsulate the VPWS virtual circuit |
| Router1 (config-if-fastethernet0)#exit |
|
| Router1 (config)# interface fastethernet 1 | Configure f1 |
| Router1 (config-if-fastethernet1)# mpls ip | Configure mpls ip |
| Router1 (config-if-fastethernet1)# xconnect 3.3.3.3 200 encapsulation mpls | Configure f1 to encapsulate the VPWS virtual circuit |
| Router1 (config-if-fastethernet1)# exit |
|
| Router1 (config)# interface serial 0/1 | Configure the frame relay interface |
| Router1 (config-if-serial0/1)# physical-layer sync |
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| Router1 (config-if-serial0/1)# encapsulation frame-relay |
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| Router1 (config-if-serial0/1)# frame-relay lmi-type ansi |
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| Router1 (config-if-serial0/1)# exit |
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| Router1 (config)# interface serial0/1.1 multipoint | Configure the frame relay sub interface |
| Router1 (config-if-serial0/1.1)# frame-relay interface-dlci 22 |
|
| Router1 (config-fr-dlci)#exit |
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| Router1 (config-if-serial0/1.1)# ip address 21.0.0.1 255.255.255.0 |
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| Router1 (config-if-serial0/1.1)# ip ospf network point-to-multipoint |
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| Router1 (config-if-serial0/1.1)# mpls ip | Enable the label forwarding of the interface |
| Router1 (config-if-serial0/1.1)# mpls ldp | Enable the LDP protocol on the interface |
| Router1 (config-if-serial0/1.1)# exit |
|
| Router1 (config)# router ospf 1 | Configure IGP (OSPF) |
| Router1 (config-ospf)# network 1.1.1.1 0.0.0.0 area 0 |
|
| Router1 (config-ospf)# network 21.0.0.0 0.0.0.255 area 0 |
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| Router1 (config-ospf)#exit |
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| Router1 (config)# mpls ldp | Configure the LDP protocol |
| Router1 (config-ldp)# router-id 1.1.1.1 | Configure the router-id of the LDP |
| Router1 (config-ldp)# targeted-peer 3.3.3.3 | Configure the LDP target peer entity |
| Router1 (config-ldp)# transport-address 1.1.1.1 | Configure the LDP transmission address |
| Router1 (config-ldp)#exit |
|
The configuration of router 2:
| Command | Description |
| Router2(config)# mpls ip | Enable the global MPLS label forwarding |
| Router2(config)# interface loopback0 | Configure the loopback port (the IP address is 2.2.2.2) |
| Router2 (config-if-loopback0)# ip address 2.2.2.2 255.255.255.255 |
|
| Router2 (config-if-loopback0)# exit |
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| Router2 (config)# interface fastethernet 1 | Configure f1 |
| Router2 (config-if-fastethernet1)# ip address 22.0.0.1 255.255.255.0 | Configure the IP address |
| Router2 (config-if-fastethernet1)# mpls ip | Configure mpls ip |
| Router2 (config-if-fastethernet1)# mpls ldp | Configure f1 to enable LDP |
| Router2 (config-if-fastethernet1)#exit |
|
| Router2 (config)# interface serial0/1 | Configure the frame relay interface |
| Router2 (config-if- serial0/1)# physical-layer sync |
|
| Router2 (config-if- serial0/1)# clock rate 2000000 |
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| Router2 (config-if- serial0/1)# encapsulation frame-relay |
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| Router2 (config-if-serial0/1)# frame-relay lmi-type ansi |
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| Router2 (config-if-serial0/1)# frame-relay intf-type dce |
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| Router2 (config-if-serial0/1)# exit |
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| Router2 (config)# interface serial0/1.1 multipoint | Configure the frame relay sub interface |
| Router2 (config-if-serial0/1.1)# frame-relay interface-dlci 22 |
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| Router2 (config-fr-dlci)#exit |
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| Router2 (config-if-serial0/1.1)# ip address 21.0.0.2 255.255.255.0 |
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| Router2 (config-if-serial0/1.1)# ip ospf network point-to-multipoint |
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| Router2 (config-if-serial0/1.1)# mpls ip | Enable the label forwarding of the interface |
| Router2 (config-if-serial0/1.1)# mpls ldp | Enable the LDP protocol on the interface |
| Router2 (config-if-serial0/1.1)# exit |
|
| Router2 (config)# router ospf 1 | Configure IGP (OSPF) |
| Router2 (config-ospf)# network 21.0.0.0 0.0.0.255 area 0 |
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| Router2 (config-ospf)# network 22.0.0.0 0.0.0.255 area 0 |
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| Router2 (config-ospf)# network 2.2.2.2 0.0.0.0 area 0 |
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| Router2 (config-ospf)#exit |
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| Router2 (config)# mpls ldp | Configure the LDP protocol |
| Router2 (config-ldp)# router-id 2.2.2.2 | Configure the router-id of the LDP |
| Router2 (config-ldp)# transport-address 2.2.2.2 | Configure the LDP transmission address |
| Router2 (config-ldp)#exit |
|
The configuration of router 3:
| Command | Description |
| Router3(config)# mpls ip | Enable the global MPLS label forwarding |
| Router3(config)# interface loopback0 | Configure the loopback port (the IP address is 3.3.3.3) |
| Router3 (config-if-loopback0)# ip address 3.3.3.3 255.255.255.255 |
|
| Router3 (config-if-loopback0)# exit |
|
| Router3(config) # port 0/0 |
|
| Router3 (config-port-0/0)# port mode access | Configure port0/0 as access mode |
| Router3 (config-port-0/0)# port access vlan 2 | Bind vlan2 with port0/0 |
| Router3 (config-port-0/0)# exit |
|
| Router3 (config)# interface vlan 2 | Configure vlan 2 |
| Router3(config-if-vlan2)#ip address 22.0.0.2 255.255.255.0 | Configure IP address |
| Router3 (config-if-vlan2)# mpls ip | Configure mpls ip |
| Router3 (config-if-vlan2)# mpls ldp | Configure vlan 2 to enable LDP |
| Router3 (config-if-vlan2)#exit |
|
| Router3 (config)# interface fastethernet 0 | Configure f0 |
| Router3 (config-if-fastethernet0)# mpls ip | Configure mpls ip |
| Router3 (config-if-fastethernet0)# xconnect 1.1.1.1 100 encapsulation mpls | Configure f0to encapsulate the VPWS virtual circuit |
| Router3 (config-if-fastethernet0)# exit |
|
| Router3 (config)# interface fastethernet 1 | Configure f1 |
| Router3 (config-if-fastethernet1)# mpls ip | Configure mpls ip |
| Router3 (config-if-fastethernet1)# xconnect 1.1.1.1 200 encapsulation mpls | Configure f1to encapsulate the VPWS virtual circuit |
| Router3 (config-if-fastethernet1)# exit |
|
| Router3 (config)# router ospf 1 | Configure IGP (OSPF) |
| Router3 (config-ospf)# network 22.0.0.0 0.0.0.255 area 0 |
|
| Router3 (config-ospf)# network 3.3.3.3 0.0.0.0 area 0 |
|
| Router3 (config-ospf)#exit |
|
| Router3 (config)# mpls ldp | Configure the LDP protocol |
| Router3 (config-ldp)# router-id 3.3.3.3 | Configure the router-id of the LDP |
| Router3 (config-ldp)# targeted-peer 1.1.1.1 | Configure the LDP target peer entity |
| Router3 (config-ldp)# transport-address 3.3.3.3 | Configure the LDP transmission address |
| Router3 (config-ldp)#exit |
|
After completing the configuration, use the show mpls ldp session command to view whether the session of targeted-peer is set up, as follows:
Router1#show mpls ldp session
Peer IP Address IF Name My Role State DeadTime
3.3.3.3 serial0/1.1 Passive OPERATIONAL 00:02:26
After setting up the session of targeted-peer, the LDP protocol distributes the VPN label. Here, you can use the show mpls forward command to view whether the VPN label is distributed, as follows:
Router1#show mpls forwarding-table l2-circuit
Codes: L - LDP, B - MP-BGP, R - RSVP, M – Mapped-Route, U - UNSPEC S - SYNC Flag
Pro Ident FEC Inlabel Outlabel Outgoing Next hop RxPkts TxPkts TxBytes Flag
L -VC- 100 / 512 serial0/1.1 3.3.3.3 0 0 0
L -VC- 200 / 513 serial0/1.1 3.3.3.3 0 0 0
The L2VPN communication needs to adopt the tunnel of the PSN network. In the instance, the PSN tunnel is the LSP (Label Switched Path) set up by LDP. The show mpls forward command can be used to view whether LSP is set up, as follows.
Router1#show mpls forwarding-table global
Codes: L - LDP, B - MP-BGP, R - RSVP, U - UNSPEC S - SYNC Flag
Pro Ident FEC Inlabel Outlabel Outgoing Next hop RxPkts TxPkts TxBytes Flag
L global 3.3.3.3/32 / 2048 serial0/1.1 21.0.0.2 0 0 0
Here, the L2VPN is set up and can communicate normally.
If the MPLS fast forwarding high-speed cache is enabled, the router adopts the high-speed cache to forward the MPLS packets. You can use the show mpls cache command to view, as follows:
Router1#show mpls cache
Ident FEC Inlabel Outgoing OLS uses Fwdpkts
-VC- 100 / serial0/1.1 |2048|512| 0 0
-VC- 200 / serial0/1.1 |2048|513| 0 0
You can see that each VC in the high-speed cache creates the fast forwarding item and uses the OLS to finish constructing the packet and then forward it.
If the fault appears, you can use the debug mpls packet command to track the packet forwarding, so as to get the information for analyzing the fault. In normal state, the following debug information can be viewed via the debug mpls packet command.
06:17:05: Receive link layer packet from interface(fastethernet0), and vc id(100)
06:17:05: Pushing VC label(512), nexthop(3.3.3.3)
06:17:05: Pushing Tunnel label(2048), nexthop(21.0.0.2)
06:17:05: Send packet out through interface(serial0/1.1)
06:17:05: Receive mpls packet from interface(serial0/1.1), LABEL(1024), TTL(2), EXP(0)
06:17:05: Popping label 1024 for Virtual Circuit
06:17:05: Send packet out through interface(fastethernet0)
First receive the L2 packet from the fastethernet0 interface, label it with VC 512 and PSN tunnel 2048, and then forward it out from the interface serial0/1.1. The Penultimate-Hop Popping (PHP) is enabled when the packet returns, so only one layer of VC label is left; he debug information shows that the MPLS packet of label 1024 is received from the interface serial0/1.1; the VC label 1024 is popped; the packet is sent out from the fastethernet0 interface.
Note -
- If the MPLS fast forwarding mechanism is enabled, the packet adopts the high-speed cache forwarding and there is no debug information. Therefore, to debug the packet forwarding information, disable the fast forwarding high-speed cache in the interface configuration mode.
- If L2VPN is bound to Ethernet sub interface and there is switch between the interface on PE and CE, the switch must support VLAN, which needs to be configured correctly.
I know this post is too long. But to cover this topic in detail for Maipu to Maipu, I need to explain in detail. So this post is long.
I know many of you will be thinking how Maipu and Cisco will work together in this scenario. Suppose one PE is Cisco and another one is Maipu. That time how will be configuration. Since in Cisco the configuration is little bit more.
I will cover that configuration in coming post.
Hope this information will help you for understanding of MPLS L2VPN.
For any feedback and query, Plz put comment with Name and Mail id.
