LNP and DTP

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LNP and DTP

Huawei LNP

The Link-type Negotiation Protocol (LNP) dynamically negotiates whether an Ethernet interface is the access or trunk interface. Huawei S series switches support LNP starting from V200R005.

Table 2-104  LNP negotiation

Local Link Type

Remote Link Type or Negotiation Status

Locally Negotiated Link Type

Final Status of the Remote Interface

Negotiation-desirable/Negotiation-auto

Access (LNP negotiation enabled)

Access

Access

Hybrid (LNP negotiation enabled)

Trunk

Hybrid

Dot1q-tunnel (LNP negotiation enabled)

Access

Dot1q-tunnel

Trunk (LNP negotiation enabled)

Trunk

Trunk

LNP negotiation not supported or disabled

Access

Uncertain

Negotiation-desirable

Negotiation-desirable

Trunk

Trunk

Negotiation-desirable

Negotiation-auto

Trunk

Trunk

Negotiation-auto

Negotiation-auto

Access

Access

imgDownload?uuid=43dc74213a4d49469188f62 NOTE:
  • The VCMP domain name affects LNP negotiation. A trunk interface is negotiated only when domain names at both ends of a link are consistent or the domain name of at least one end is empty; otherwise, an access interface is negotiated.
  • The Ethernet interface that is negotiated as an access interface joins VLAN 1 by default. The Ethernet interface that is negotiated as a trunk interface allows all VLANs by default.
Cisco DTP

The Dynamic Trunking Protocol (DTP) dynamically negotiates whether an Ethernet interface is the access or trunk interface.

Table 2-105  DTP negotiation

Configured Link Type of an Interface

Negotiated Link Type of an Interface

Switchport mode access

The interface is configured to work in access mode forcibly.

Switchport mode dynamic auto

If the remote interface works in trunk or desirable mode, the local interface works in trunk mode through negotiation.

Switchport mode dynamic desirable

If the remote interface works in trunk, desirable, or auto mode, the local interface works in trunk mode through negotiation.

Switchport mode trunk

The interface is configured to work in trunk mode forcibly.

Switchport nonegotiate

This command is used to enable the interface not to send DTP packets, and can be used on only the interface in trunk or access mode.

To establish a trunk link, you must manually configure interfaces at both ends to work in trunk mode.

imgDownload?uuid=43dc74213a4d49469188f62 NOTE:
  • Devices at both ends must have the same VTP domain name to ensure successful DTP negotiation.
  • DTP supports the Inter-Switch Link (ISL) and IEEE 802.1Q. ISL is a Cisco proprietary encapsulation protocol, and IEEE 802.1Q is a standard protocol.

Comparison Between LNP and DTP

Table 2-106  Function support

Function

Huawei S Series Switches

Cisco Switches

Enabling or disabling global auto-negotiation of the link type of an interface

Supported

Global auto-negotiation of the link type of an interface is enabled by default.

For devices such as access devices that do not require dynamic negotiation, LNP can be disabled globally. After LNP is disabled, the device stops sending LNP packets. The network burden is therefore reduced.

Not supported

Enabling or disabling auto-negotiation of the link type of an interface

Supported

Auto-negotiation of the link type of an interface is enabled by default.

Supported

See the Cisco documentation.

Dynamically negotiating the link type

Supported

Supported

Delivering VLAN information about an interface based on the negotiation result after the link type is negotiated dynamically

Supported

Supported

Displaying negotiation information about the link type of an interface

Supported

Supported

Automatic recovery of the dynamically negotiated link state after the active/standby switchover

Supported

Supported

Table 2-107  Differences in command formats

Function

Command on Huawei S Series Switches

Command on Cisco Switches

Configure the link dynamic negotiation mode as auto.

port link-type negotiation-autoswitchport mode dynamic auto

Configure the link dynamic negotiation mode as desirable.

port link-type negotiation-desirableswitchport mode dynamic desirable

Remove an interface from a VLAN in negotiation mode. For example, remove an interface from VLAN 10.

There is no command used to remove an interface from VLAN 10. You can specify the VLANs that interfaces can be added to.

port trunk allow-pass only-vlan 1 to 9 11 to 4094
switchport trunk allowed vlan remove 10

Disable auto-negotiation of an interface.

port negotiation disableswitchport nonegotiate

Disable global LNP.

lnp disable

Not supported

Modify the packet encapsulation mode.

Huawei supports only encapsulation based on the standard protocol, without any configuration.

switchport trunk encapsulation dot1q

LNP and DTP Interworking and Replacement Solution Analysis

DTP and LNP are both proprietary protocols, so they cannot interwork. The two protocols can replace each other. Two solutions are available:
  • Network-wide replacement: All Cisco DTP switches are replaced by Huawei S series switches that support LNP.
  • Single replacement: One Cisco switch is replaced by a Huawei S series switch. The remote switch is still a Cisco switch. In this situation, you need to configure the interface of the remote Cisco switch to work in non-negotiation mode.
  • x
  • convention:

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