knowledge focus
- link aggregation
- Introduction to Link Aggregation:
Ethernet link aggregation Eth-Trunk is called link aggregation for short. It bundles multiple Ethernet physical links into a logical link to increase the link bandwidth. At the same time, these bundled links can effectively improve link reliability through mutual dynamic backup.
- Purpose:
- increase bandwidth
The maximum bandwidth of a link aggregation interface can reach the sum of the bandwidths of all member interfaces.
- Improve reliability
When an active link fails, traffic can be switched to other available member links, thereby improving the reliability of the link aggregation interface.
- load sharing
In a link aggregation group, load sharing can be realized on active links of each member.
- Manual load sharing
- Introduction:
In manual load balancing mode, the establishment of Eth-Trunk and the addition of member interfaces are manually configured without the participation of the link aggregation control protocol. In this mode, all active links participate in data forwarding and share traffic evenly, so it is called load sharing mode. If an active link fails, the link aggregation group automatically shares the traffic evenly among the remaining active links. When a large link bandwidth needs to be provided between two directly connected devices and the devices do not support LACP, the manual load balancing mode can be used.
- Load sharing mode of link aggregation:
Based on original IP
Based on destination IP
Based on original MAC
Destination-based MAC
Based on source and destination IP
Based on source and destination MAC
- Example of manual preparation:
- Knowledge point 2:
- lacp
- Introduction:
As a link aggregation technology, Eth-Trunk in manual load balancing mode can aggregate multiple physical interfaces into one Eth-Trunk port to improve bandwidth. Faults such as link layer faults and link misconnections are detected.
In order to improve the fault tolerance of Eth-Trunk, provide backup function, and ensure high reliability of member links, Link Aggregation Control Protocol LACP (Link Aggregation Control Protocol) appeared. LACP mode is a kind of link aggregation using LACP model.
LACP provides a standard negotiation method for devices exchanging data, so that devices can automatically form an aggregated link according to their own configuration and start the aggregated link to send and receive data. After the aggregation link is formed, LACP is responsible for maintaining the link status, and automatically adjusts or dissolves the link aggregation when the aggregation condition changes.
- The basic concept of lacp:
- System LACP priority
In LACP mode, the active interfaces selected by the devices at both ends must be consistent, otherwise the link aggregation group cannot be established. To keep the active interfaces at both ends consistent, one end can have a higher priority, and the other end can select an active interface according to the end with the higher priority. The system LACP priority is a parameter configured to distinguish the priorities of devices at both ends. The smaller the system LACP priority value, the higher the priority.
- How to determine active and passive ends:
① Determined by device LACP priority. The lower the LACP priority is, the more priority it is, and the priority device is the active device, and the default value is 32768.
② Determined by the system MAC address. The smaller the MAC address, the higher the priority, and the device with priority is the active device.
- Interface LACP priority
The interface LACP priority is used to distinguish the priorities of different interfaces in the same Eth-Trunk when they are selected as active interfaces. The interface with higher priority will be selected as the active interface first. The smaller the interface LACP priority value, the higher the priority.
- How to determine the active link:
By configuring the upper threshold of the number of active interfaces, and then configuring the lacp priority of member interfaces, the link with the highest priority is used as the active link, and the rest of the links can be used as backup links.
- Example of lacp configuration:
