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.
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 |
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.
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. |
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
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 |
Function | Command on Huawei S Series Switches | Command on Cisco Switches |
|---|---|---|
Configure the link dynamic negotiation mode as auto. | port link-type negotiation-auto | switchport mode dynamic auto |
Configure the link dynamic negotiation mode as desirable. | port link-type negotiation-desirable | switchport 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 disable | switchport 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
- 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.
