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 transparent transmission for packets of the specified protocol 3

 

 

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

 

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.

·     MVRP.

·     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

 

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:

2.     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.

3.     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

 

L2PT tasks at a glance

To configure L2PT, perform the following tasks:

1.     (Optional.) Enabling transparent transmission for packets of the specified protocol

Enabling transparent transmission for packets of the specified protocol

About this task

This feature is applicable to L2VPN networks such as VPLS and VPWS networks. With this feature disabled on a Layer 3 Ethernet subinterface or Ethernet service instance acting as an AC, it drops received packets of the CDP, LACP, LLDP, and UDLD protocols. As a result, user networks across sites cannot communicate by using these Layer 2 protocols. With this feature enabled on a Layer 3 Ethernet subinterface or Ethernet service instance on a PE, the PE can receive and transparently transmit packets of the specified protocol. These packets are not encapsulated with the multicast destination MAC address for tunneled packets. When the packets reach the peer PE through a PW, the peer PE forwards the packets to the corresponding user sites.

This feature is applicable to L2VPN networks such as VPLS and VPWS networks. With this feature disabled on a Layer 3 Ethernet subinterface or Ethernet service instance acting as an AC, it drops received packets of the LACP or LLDP protocols. As a result, user networks across sites cannot communicate by using these Layer 2 protocols. With this feature enabled on a Layer 3 Ethernet subinterface or Ethernet service instance on a PE, the PE can receive and transparently transmit packets of the specified protocol. These packets are not encapsulated with the multicast destination MAC address for tunneled packets. When the packets reach the peer PE through a PW, the peer PE forwards the packets to the corresponding user sites.

Restrictions and guidelines

The following restrictions apply to the cards in the table below:

·     For different subinterfaces of the same primary interface on a single card, if a subinterface is configured as an AC and executes the l2protocol transparent lldp enable command, all other subinterfaces that are not bound to an AC will process packets in transparent mode.

·     For different subinterfaces of the same primary interface on a single card, if they are bound to the same or different VSIs, as long as one subinterface is enabled with packet transparent transmission, all other subinterfaces, regardless of whether they are configured with packet transparent transmission, will process packets in transparent mode.

 

Card category	Cards
CEPC	NP5 cards-CEPC
CSPEX	NP5 cards-CSPEX
SPE	NP5 cards-SPE

 

For the following cards, if different subinterfaces of the same primary interface are bound to the same VSI, as long as one subinterface is enabled with protocol transparent transmission, the other subinterfaces will also be treated as protocol transparent transmission regardless of their configuration.

 

Card category	Cards
CEPC	NPS400 cards-CEPC
CSPEX	NPS400 cards-CSPEX
SPE	NPS400 cards-SPE

 

For transparent transmission configurations of different packets in the network, see the following table.

 

Packet type	Network type	Configuration of transparent packet transmission
eoam3ah	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	l2protocol transparent lacp enable
lldp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	l2protocol transparent lldp enable
gmrp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
gvrp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
dldp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
hgmp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
vtp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
dtp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
cdp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
udld	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
pagp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
pvst+	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
stp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
lacp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	l2protocol transparent lacp enable
mvrp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
e-lmi	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
e-lmi	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
802.1X	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.
sstp	SRv6 VPLS: Transparent transmission SRv6 VPWS: Transparent transmission	None.

 

On a Layer 3 interface that has LLDP packet transparent transmission enabled, do not configure the interface to operate in dynamic aggregation mode to prevent aggregate interface flapping.

On a Layer 3 interface that has LLDP packet transparent transmission enabled, disable LLDP to prevent LLDP exceptions on devices attached to the interface.

For the following card, if different subinterfaces of the same primary interface are bound to the same VSI, as long as one subinterface is enabled with protocol transparent transmission, the others will also be treated as protocol transparent transmission regardless of their configuration.

Procedure

1.     Enter system view.

system-view

2.     Enter interface view.

¡     Enter Layer 3 Ethernet interface view.

interface interface-type interface-number

¡     Enter Layer 3 Ethernet subinterface view.

interface interface-type interface-number.subnumber

¡     Enter Layer 3 aggregate interface view.

interface route-aggregation interface-number

¡     Enter Layer 3 aggregate subinterface view.

interface route-aggregation interface-number.subnumber

¡     Enter Layer 3 FlexE logical interface view.

interface flexe interface-number

¡     Enter Layer 3 FlexE logical subinterface view.

interface flexe interface-number.subnumber

3.     Enable transparent transmission for packets of the specified protocol.

l2protocol transparent { lacp | lldp } enable

By default, transparent transmission is disabled for packets of the LACP and LLDP protocols, and enabled for other packets.