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Simple writing and introduction of link aggregation technology
Link Aggregation Technology
The meaning of link aggregation technology: Link aggregation is a method of bundling a group of physical interfaces together as a logical interface to increase bandwidth. It is also called multi-interface load balancing to form a link aggregation group. The establishment of a link aggregation group can provide higher communication bandwidth and higher reliability. Link aggregation not only provides redundancy protection for device communication, but also does not require hardware upgrades.
1. Realization conditions of link aggregation
- Each Eth-Trunk interface can contain up to 8 member interfaces
- Member interfaces cannot be configured with any services and static MAC addresses
- When a member interface is added to the Eth-Trunk, it must be the default hybrid interface
- Eth-Trunk interfaces cannot be nested, that is, member interfaces cannot be Eth-Trunk
- An Ethernet interface can only be added to one Eth-Trunk interface. If you want to join another Eth-Trunk interface, you must exit the original Eth-Trunk interface
- The member interface types of an Eth-Trunk interface must be the same type, for example: FE port and GE port cannot be added to the same Eth-Trunk interface
- You can add the Ethernet interfaces on the interface board to the same Eth-Trunk
- If the local device uses Eth-Trunk, the peer interface directly connected to the member interface must be bundled with the Eth-Trunk interface so that both ends can communicate normally
- When the member interface rates are inconsistent, the interface with a low rate in actual use may be congested, causing packet loss
- When the member interface joins the Eth-Trunk, the MAC address is learned according to the Eth-Trunk, not according to the member interface.
Two, the three main advantages of link aggregation
- Increase bandwidth
The maximum bandwidth of the link aggregation interface can reach the sum of the bandwidth of the 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 on the active links of each member can be realized.
Three, specific use
1. Two-tier aggregation
Example: The 
above figure is a network topology diagram. We perform Layer 2 link aggregation between LSW4 and LSW5.
We create link aggregation, then change the link aggregation mode to trunk mode, and finally add the members that need aggregation to the link aggregation.
LSW4
<Huawei>undo terminal monitor
Info: Current terminal monitor is off.
<Huawei>sys
Enter system view, return user view with Ctrl+Z.
[Huawei]vlan 2
[Huawei-vlan2]int e0/0/1
[Huawei-Ethernet0/0/1]port link-type access
[Huawei-Ethernet0/0/1]port default vlan 2
[Huawei-Ethernet0/0/1]q
[Huawei]int Eth-Trunk 1
[Huawei-Eth-Trunk1]port link-type trunk
[Huawei-Eth-Trunk1]port trunk allow-pass vlan all
[Huawei-Eth-Trunk1]int e0/0/2
[Huawei-Ethernet0/0/2]eth-trunk 1
Info: This operation may take a few seconds. Please wait for a moment...done.
[Huawei-Ethernet0/0/2]int e0/0/3
[Huawei-Ethernet0/0/3]eth-trunk 1
Info: This operation may take a few seconds. Please wait for a moment...done.
LSW5
<Huawei>undo terminal monitor
Info: Current terminal monitor is off.
<Huawei>sys
Enter system view, return user view with Ctrl+Z.
[Huawei]vlan 2
[Huawei-vlan2]int e0/0/1
[Huawei-Ethernet0/0/1]port link-type access
[Huawei-Ethernet0/0/1]port default vlan 2
[Huawei-Ethernet0/0/1]q
[Huawei]int Eth-Trunk 1
[Huawei-Eth-Trunk1]port link-type trunk
[Huawei-Eth-Trunk1]port trunk allow-pass vlan all
[Huawei-Eth-Trunk1]q
[Huawei]int e0/0/2
[Huawei-Ethernet0/0/2]eth-trunk 1
Info: This operation may take a few seconds. Please wait for a moment...done.
[Huawei-Ethernet0/0/2]int e0/0/3
[Huawei-Ethernet0/0/3]eth-trunk 1
Info: This operation may take a few seconds. Please wait for a moment...done.
2. Three-layer aggregation
Example:
The network topology diagram is as above. Perform three-layer link aggregation on ports g0/0/1 and g0/0/2 between switches CE1 and CE2, and add loopback ports to CE1 and CE2 for testing. After completing the operation, test PC1 and PC2 connectivity.
CE1
<HUAWEI>undo terminal monitor
Info: Current terminal monitor is off.
<HUAWEI>sys
Enter system view, return user view with return command.
[~HUAWEI]int
[~HUAWEI]interface Eth-Trunk 1
[*HUAWEI-Eth-Trunk1]undo portswitch
[*HUAWEI-Eth-Trunk1]ip add 10.1.1.1 24
[*HUAWEI-Eth-Trunk1]q
[*HUAWEI]int g1/0/0
[*HUAWEI-GE1/0/0]undo shutdown
[*HUAWEI-GE1/0/0]eth-trunk 1
[*HUAWEI-GE1/0/0]int g1/0/1
[*HUAWEI-GE1/0/1]undo shutdown
[*HUAWEI-GE1/0/1]eth-trunk 1
[*HUAWEI-GE1/0/1]q
[*HUAWEI]interface LoopBack 0
[*HUAWEI-LoopBack0]ip address 192.168.1.100 32
[*HUAWEI-LoopBack0]q
[*HUAWEI]ip route-static 192.168.2.100 32 10.1.1.2
[*HUAWEI]q
Warning: Uncommitted configurations found. Are you sure to commit them before ex
iting? [Y(yes)/N(no)/C(cancel)]:Y
CE2
<HUAWEI>undo terminal monitor
Info: Current terminal monitor is off.
<HUAWEI>sys
Enter system view, return user view with return command.
[~HUAWEI]int Eth-Trunk 1
[*HUAWEI-Eth-Trunk1]undo portswitch
[*HUAWEI-Eth-Trunk1]ip add 10.1.1.2 24
[*HUAWEI-Eth-Trunk1]q
[*HUAWEI]int g1/0/0
[*HUAWEI-GE1/0/0]undo shutdown
[*HUAWEI-GE1/0/0]eth-trunk 1
[*HUAWEI-GE1/0/0]int g1/0/1
[*HUAWEI-GE1/0/1]undo shutdown
[*HUAWEI-GE1/0/1]eth-trunk 1
[*HUAWEI-GE1/0/1]q
[*HUAWEI]interface LoopBack 0
[*HUAWEI-LoopBack0]ip add 192.168.2.100 32
[*HUAWEI-LoopBack0]q
[*HUAWEI]ip route-static 192.168.1.100 32 10.1.1.1
[*HUAWEI]q
Warning: Uncommitted configurations found. Are you sure to commit them before ex
iting? [Y(yes)/N(no)/C(cancel)]:Y
Test connectivity results:
<HUAWEI>ping 192.168.2.100
PING 192.168.2.100: 56 data bytes, press CTRL_C to break
Reply from 192.168.2.100: bytes=56 Sequence=1 ttl=255 time=12 ms
Reply from 192.168.2.100: bytes=56 Sequence=2 ttl=255 time=4 ms
Reply from 192.168.2.100: bytes=56 Sequence=3 ttl=255 time=5 ms
Reply from 192.168.2.100: bytes=56 Sequence=4 ttl=255 time=4 ms
Reply from 192.168.2.100: bytes=56 Sequence=5 ttl=255 time=4 ms
--- 192.168.2.100 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 4/5/12 ms
[~HUAWEI]ping 192.168.1.100
PING 192.168.1.100: 56 data bytes, press CTRL_C to break
Reply from 192.168.1.100: bytes=56 Sequence=1 ttl=255 time=11 ms
Reply from 192.168.1.100: bytes=56 Sequence=2 ttl=255 time=8 ms
Reply from 192.168.1.100: bytes=56 Sequence=3 ttl=255 time=5 ms
Reply from 192.168.1.100: bytes=56 Sequence=4 ttl=255 time=5 ms
Reply from 192.168.1.100: bytes=56 Sequence=5 ttl=255 time=4 ms
--- 192.168.1.100 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 4/6/11 ms
to sum up
With the continuous expansion of network scale, users have put forward higher and higher requirements on the bandwidth and reliability of backbone links. In the traditional technology, the method of replacing the high-speed interface board or replacing the equipment supporting the high-speed interface board is commonly used to increase the bandwidth, but this kind of solution requires a high cost and is not flexible enough.
The use of link aggregation technology can achieve the purpose of increasing link bandwidth by bundling multiple physical interfaces into a logical interface without hardware upgrades. While achieving the purpose of increasing bandwidth, link aggregation uses a backup link mechanism, which can effectively improve the reliability of links between devices.