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Preface
What are the methods when you want to realize the communication between different VLANs?
One, single-arm routing
One-arm routing is composed of Layer 2 switches and routers. The principle is that the router re-encapsulates the MAC address and converts the Vlan label. Switches and PCs use access, and routers use trunk.
As shown in the figure, if PC1 and PC2 are not in the same vlan, how to configure if they want to be the same? One-arm routing can be used here.
Switch configuration: 
router configuration: 
finally PCs ping each other:
Layer 2 and Layer 3 switching
The three-layer exchange has a routing function, and the principle is that one route is exchanged many times.
Configuration information: 
experimental results:
Three, link aggregation
Port binding technology: Link aggregation is a method of bundling a group of physical interfaces together as a logical interface to increase bandwidth, also known as multi-interface load balancing group or link aggregation group, which establishes a link between two devices Road aggregation group can provide higher communication.
Conditions for the realization of link aggregation/port aggregation/port binding:
1) Each eth-trunk interface can contain up to 8 member interfaces
2) member interfaces cannot be configured with any services and static MAC addresses
3) member interfaces are added to eth-trunk It must be the default hybrid type interface
4) The eth-trunk interface cannot be nested, that is, the member interface cannot be an eth-trunk
5) An Ethernet interface can only be added to an eth-trunk interface, if you need to add other eth- The trunk interface must first exit the original eth-trunk interface
6) The member interfaces of an eth-trunk interface must be of the same type, for example: FE and GE ports cannot be added to the same eth-trunk interface
7) Different interface boards can be used Ethernet interface is added to the same eth-trunk
. 8) If the local device uses eth-trunk, and the members directly connected to the interface must be bundled into a docking port eth-trunk interfaces ends can not communicate ,,
9) when the member When the rate of the interface is inconsistent, the interface with a low rate in actual use may be congested, resulting in packet loss.
10) When the member interface is added to the eth-trunk, the MAC address is learned according to the eth-trunk instead of the member interface Come to learn
Remember that when doing link aggregation, you must set the link type last. Finally, switch 4, I set a few active and several backups for him. The number followed by max active-linknumber is the number of active ones, for example, you have four. If you want three lines to be active and one line to be backed up, you only need to enter 3 in the back. In the query command, enter display trunkmembership eth-trunk 1 in the aggregation mode, and operate up to open, on the contrary, operate down to close.