Contents

Configuring L2PT· 1

About L2PT· 1

L2PT application scenario· 1

Supported protocols· 1

L2PT operating mechanism·· 2

L2PT tasks at a glance· 3

Enabling L2PT· 3

Restrictions and guidelines for L2PT· 3

Enabling L2PT for a protocol in Layer 2 Ethernet interface view· 3

Enabling L2PT for a protocol in Layer 2 aggregate interface view· 4

Setting the destination multicast MAC address for tunneled packets· 4

Display and maintenance commands for L2PT· 5

L2PT configuration examples· 5

Example: Configuring L2PT for STP· 5

 

Configuring L2PT

About L2PT

Layer 2 Protocol Tunneling (L2PT) can transparently send Layer 2 protocol packets from geographically dispersed customer networks across a service provider network or drop them.

L2PT application scenario

Dedicated lines are used in a service provider network to build user-specific Layer 2 networks. As a result, a customer network contains sites located at different sides of the service provider network.

As shown in Figure 1, Customer A's network is divided into network 1 and network 2, which are connected by the service provider network. For Customer A's network to implement Layer 2 protocol calculations, the Layer 2 protocol packets must be transmitted across the service provider network.

Upon receiving a Layer 2 protocol packet, the PEs cannot determine whether the packet is from the customer network or the service provider network. They must deliver the packet to the CPU for processing. In this case, the Layer 2 protocol calculation in Customer A's network is mixed with the Layer 2 protocol calculation in the service provider network. Neither the customer network nor the service provider network can implement independent Layer 2 protocol calculations.

Figure 1 L2PT application scenario

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L2PT is introduced to resolve the problem. L2PT provides the following functions:

·     Multicasts Layer 2 protocol packets from a customer network in a VLAN. Dispersed customer networks can complete an independent Layer 2 protocol calculation, which is transparent to the service provider network.

·     Isolates Layer 2 protocol packets from different customer networks through different VLANs.

Supported protocols

H3C devices support L2PT for the following protocols:

·     CDP.

·     DLDP.

·     EOAM.

·     GVRP.

·     LACP.

·     LLDP.

·     PAgP.

·     PVST.

·     STP (including STP, RSTP, and MSTP).

·     UDLD.

·     VTP.

L2PT operating mechanism

As shown in Figure 2, L2PT operates as follows:

·     When a port of PE 1 receives a Layer 2 protocol packet from the customer network in a VLAN, it performs the following operations:

¡     Multicasts the packet out of all customer-facing ports in the VLAN except the receiving port.

¡     Encapsulates the packet with a specified destination multicast address, and multicasts it out of all ISP-facing ports in the VLAN. The encapsulated packet is called the BPDU tunneled packet.

·     When a port of PE 2 in the VLAN receives the tunneled packet from the service provider network, it performs the following operations:

¡     Multicasts the packet out of all ISP-facing ports in the VLAN except the receiving port.

¡     Decapsulates the packet and multicasts the decapsulated packet out of all customer-facing ports in the VLAN.

Figure 2 L2PT operating mechanism

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For example, as shown in Figure 3, PE 1 receives an STP packet (BPDU) from network 1 to network 2. CEs are the edge devices on the customer network, and PEs are the edge devices on the service provider network. L2PT processes the packet as follows:

1.     PE 1 performs the following operations:

a.     Encapsulates the packet with a specified destination multicast MAC address (010f-e200-0003 by default).

b.     Sends the tunneled packet out of all ISP-facing ports in the packet's VLAN.

2.     Upon receiving the tunneled packet, PE 2 decapsulates the packet and sends the BPDU to CE 2.

Through L2PT, both the ISP network and Customer A's network can perform independent spanning tree calculations.

Figure 3 L2PT network diagram

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L2PT tasks at a glance

To configure L2PT, perform the following tasks:

1.     Enabling L2PT

This feature is applicable only to customer-facing ports.

2.     (Optional.) Setting the destination multicast MAC address for tunneled packets

Enabling L2PT

Restrictions and guidelines for L2PT

·     To enable L2PT for a Layer 2 protocol on a port, perform the following tasks:

¡     Enable the protocol on the connected CE, and disable the protocol on the port.

¡     Disable the protocol (for example, STP) on the PE ports connecting to an aggregate interface on a CE when the following conditions exist:

-     The protocol is running on the aggregate interface on the CE.

-     The aggregate interface on the CE connects to an L2PT-enabled port on the PE.

¡     Enable L2PT on PE ports connected to a customer network. If you enable L2PT on ports connected to the service provider network, L2PT determines that the ports are connected to a customer network.

¡     Make sure the VLAN tags of Layer 2 protocol packets are not changed or deleted for the tunneled packets to be transmitted correctly across the service provider network.

·     L2PT for LLDP supports LLDP packets from only nearest bridge agents.

·     You can enable L2PT on a member port of a Layer 2 aggregation group, but the configuration does not take effect.

·     Do not enable L2PT on a port that is going to join a service loopback group.

Enabling L2PT for a protocol in Layer 2 Ethernet interface view

Restrictions and guidelines

LACP and EOAM require point-to-point transmission. If you enable L2PT on a Layer 2 Ethernet interface for LACP or EOAM, L2PT multicasts LACP or EOAM packets out of customer-facing ports. As a result, the transmission between two CEs is not point-to-point. To ensure point-to-point transmission for the LACP or EOAM packets, you must configure other features (for example, VLAN).

Procedure

1.     Enter system view.

system-view

2.     Enter Layer 2 Ethernet interface view.

interface interface-type interface-number

3.     Enable L2PT for a protocol.

l2protocol { cdp | dldp | eoam | gvrp | lacp | lldp | pagp | pvst | stp | udld | vtp } tunnel dot1q

By default, L2PT is disabled for all protocols.

Enabling L2PT for a protocol in Layer 2 aggregate interface view

1.     Enter system view.

system-view

2.     Enter Layer 2 aggregate interface view.

interface bridge-aggregation interface-type interface-number

3.     Enable L2PT for a protocol.

l2protocol { cdp | gvrp | lacp | lldp | pagp | pvst | stp | udld | vtp } tunnel dot1q

By default, L2PT is disabled for all protocols.

Setting the destination multicast MAC address for tunneled packets

About this task

The default destination multicast MAC address for tunneled packets is 010f-e200-0003. You can modify the destination multicast MAC address for tunneled packets of the specific protocol or all protocols.

Restrictions and guidelines

For tunneled packets to be recognized, set the same destination multicast MAC addresses for packets of the same protocol on PEs that are connected to the same customer network.

As a best practice, set different destination multicast MAC addresses on PEs connected to different customer networks. It prevents L2PT from sending packets of a customer network to another customer network.

Procedure

1.     Enter system view.

system-view

2.     Set the destination multicast MAC address for tunneled packets of all protocols.

l2protocol tunnel-dmac mac-address

By default, 010f-e200-0003 is used for tunneled packets.

Display and maintenance commands for L2PT

Execute display commands in any view and reset commands in user view.

 

Task	Command
Display L2PT statistics.	display l2protocol statistics [ interface interface-type interface-number ]
Clear L2PT statistics.	reset l2protocol statistics [ interface interface-type interface-number ]

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L2PT configuration examples

Example: Configuring L2PT for STP

Network configuration

As shown in Figure 4, the MAC addresses of CE 1 and CE 2 are 00e0-fc02-5800 and 00e0-fc02-5802, respectively. MSTP is enabled in Customer A's network, and default MSTP settings are used.

Perform the following tasks on the PEs:

·     Configure the ports that connect to CEs as access ports, and configure the ports in the service provider network as trunk ports. Configure ports in the service provider network to allow packets from any VLAN to pass.

·     Enable L2PT for STP to enable Customer A's network to implement independent spanning tree calculation across the service provider network.

·     Set the destination multicast MAC address to 0100-0ccd-cdd0 for tunneled packets.

Figure 4 Network diagram

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Procedure

1.     Configure PE 1:

# Set the destination multicast address to 0100-0ccd-cdd0 for tunneled packets.

<PE1> system-view

[PE1] l2protocol tunnel-dmac 0100-0ccd-cdd0

# Create VLAN 2.

[PE1] vlan 2

[PE1-vlan2] quit

# Configure Twenty-FiveGigE 1/0/1 as an access port and assign the port to VLAN 2.

[PE1] interface twenty-fivegige 1/0/1

[PE1-Twenty-FiveGigE1/0/1] port access vlan 2

# Disable STP and enable L2PT for STP on Twenty-FiveGigE 1/0/1.

[PE1-Twenty-FiveGigE1/0/1] undo stp enable

[PE1-Twenty-FiveGigE1/0/1] l2protocol stp tunnel dot1q

[PE1-Twenty-FiveGigE1/0/1] quit

# Configure Twenty-FiveGigE 1/0/2 connected to the service provider network as a trunk port, and assign the port to all VLANs.

[PE1] interface twenty-fivegige 1/0/2

[PE1-Twenty-FiveGigE1/0/2] port link-type trunk

[PE1-Twenty-FiveGigE1/0/2] port trunk permit vlan all

[PE1-Twenty-FiveGigE1/0/2] quit

2.     Configure PE 2 in the same way PE 1 is configured. (Details not shown.)

Verifying the configuration

# Verify that the root bridge of Customer A's network is CE 1.

<CE2> display stp root

 MST ID   Root Bridge ID        ExtPathCost IntPathCost Root Port

 0        32768.00e0-fc02-5800  0           0

# Verify that the root bridge of the service provider network is not CE 1.

[PE1] display stp root

 MST ID   Root Bridge ID        ExtPathCost IntPathCost Root Port

 0        32768.0cda-41c5-ba50  0           0