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In the routing / switching field, the trunk port of VLAN is called trunk. Trunk technology is used to interconnect switches so that different VLAN can communicate with the same VLAN in other switches through shared links. The ports that are interconnected between switches are called trunk ports. Trunk is a technology based on OSI layer 2 data Link layer (DataLinkLayer). Trunk can not realize the communication between different VLAN, and the communication between different VLAN needs to be realized through layer 3 devices (routing / layer 3 switch).

LACP, LACP (Link Aggregation Control Protocol, Link aggregation Control Protocol) based on IEEE802.3ad standard, is a protocol to realize dynamic aggregation of links. The LACP protocol exchanges information with the peer through LACPDU (Link Aggregation Control Protocol Data Unit, link aggregation control protocol data unit). When the LACP protocol for a port is enabled, the port advertises its system priority, system MAC address, port priority, port number, and operation Key to the peer by sending LACPDU. After receiving the information, the peer compares the information with the information saved by other ports to select the port that can be converged, so that the two sides can agree on whether the port can join or exit a dynamic aggregation group. Port trunking is the aggregation of multiple ports together to form an aggregation group to achieve the sharing of output / input load among the member ports in the aggregation group, and also provides higher connection reliability.

Both E-trunk and Eth-trunk are link aggregation technologies, so what's the difference between E-trunk and Eth-trunk?

Eth-Trunk: generally refers to the link aggregation of the same device

A switch bundles these interfaces to form an Eth-Trunk interface, thus achieving the purpose of increasing bandwidth and improving reliability.

The link connected by the Trunk interface can be regarded as a point-to-point directly connected link.

The advantages of Trunk are:

Load sharing

Load sharing can be realized through Trunk interface. Traffic load sharing can be achieved within an Eth-Trunk interface.

Improve reliability

When a physical link connected to a member interface fails, traffic is switched to other available links, thus improving the reliability of the entire Trunk link.

Increase bandwidth

The total bandwidth of the Trunk interface is the sum of the bandwidth of each member interface.

If two switches are stacked, the links of the ports are aggregated into a cross-frame Eth-Trunk (across different backplanes or service boards)

E-Trunk: generally refers to aggregation across device links

E-Trunk (Enhanced Trunk) is a mechanism to achieve cross-device link aggregation, which is extended based on LACP (the standard for link aggregation of single device) to realize link aggregation among multiple devices. As a result, the reliability of the link is improved from the single board level to the equipment level.

The E-Trunk mechanism is mainly applied to the link protection between VPLS and PE and the protection against node failures of PE devices when CE is connected to VPLS, VLL and PWE3 networks. Before using E-Trunk, CE could only be returned to one PE device over the Eth-Trunk link. If the Eth-Trunk fails or the PE device fails, CE will not be able to continue to communicate with the PE device. After using E-Trunk, CE can be doubly returned to PE, thus achieving inter-device protection.

As shown in the following figure:

If the two devices are clustered with CSS, then the two devices can be regarded as one device, and the link aggregation between the two physical devices is achieved through Eth-trunk, which is equivalent to the link aggregation of the same device, rather than the link aggregation across devices.

Two examples are attached: stack-based two-tier architecture data center network deployment

Products: Huawei CE12800/CE6800/CE5800 series products

The data center network shown in the following figure is deployed in a two-tier manner of access layer and core layer. In order to simplify the network and improve the reliability, the core layer consists of two CE12800 CSS, and the access layer consists of multiple CE6800 iStack. The access layer and the core layer are connected by cross-device Eth-Trunk to eliminate the layer 2 loop. At the same time, the bandwidth bearing pressure of the inter-frame link is reduced through the traffic local priority forwarding function of Eth-Trunk. The core layer isolates service network segment routing from public network routing by creating VRF, deploys firewalls by side-by-side mode, and two firewalls carry out dual-computer hot backup to ensure high reliability.

Stack-based data center network deployment with three-tier architecture

Products: Huawei CE12800/CE6800/CE5800 series products

In the three-layer data center network shown in the figure below, the core layer is composed of two CE12800, and the two devices are aggregated through two 10GE links to ensure the high reliability of the links. The aggregation layer uses CE12800 switch stack to realize redundant backup, and the stack is connected with upstream and downstream devices through cross-frame Eth-Trunk. At the same time, the bandwidth bearing pressure of the inter-frame link is reduced through the traffic local priority forwarding function of Eth-Trunk. The aggregation layer isolates service network segment routing from public network routing by creating VRF, deploys firewalls by side-by-side mode, and two firewalls carry out dual-computer hot backup to ensure high reliability.

Add:

IStack stacking refers to the combination of multiple switch devices that support stacking characteristics to logically form an overall switching device. IStack is a virtualization technology, which virtualizes multiple devices in the same layer of the network into a single logical device without changing the physical topology of the network, so as to simplify the network structure, simplify the deployment of network protocols, and improve the reliability and manageability of the network. IStack, a virtual device, not only has the advantages of low cost of box devices, but also has the advantages of expansibility and high reliability of frame devices.

Network horizontal Virtualization example

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