Hello,
Today, I would like to share with you this topic Physical link aggregation-improve link utilization.
What should I do when the utilization rate of a microwave link has been increased to the limit through ultra-high modulation mode and frame header compression to maximize the throughput, but still cannot meet the service traffic demand and still needs more bandwidth?
The simplest answer is: create a new microwave link!
Use multiple microwave links to transmit large-bandwidth services together, which is link aggregation. When link aggregation, it faces the problem of how to perform load sharing among member links.
Traditionally, the air interface LAG technology based on the 802.3ad protocol uses the Hash algorithm to distribute service messages to each link, which is suitable for data traffic that contains a lot of service flows. Usually LAG's Hash algorithm relies on MAC address, IP address, MPLS label or a combination of these features.
In most cases, the Hash algorithm can achieve load sharing on each link, and the load of some links may be unbalanced. In some cases, even if the business traffic does not exceed the total bandwidth of the aggregation group, packet loss may occur.
If we compare multiple microwave links to multiple roads connecting two places, the LAG algorithm is equivalent to dispatching vehicles based on the type of goods (material, color, category, etc.), rather than dispatching based on the usage of the road. Obviously, this cannot guarantee full utilization of road resources.
To make full use of road resources, it should be independent of the type of goods, but according to the capacity (bandwidth) of each road to dispatch vehicles, which produces a physical link aggregation algorithm.
Physical link aggregation distributes traffic according to link bandwidth to achieve load sharing. This link aggregation method does not depend on the composition of Layer 2 or Layer 3 service flows, so it can also be called L1 LAG.
The physical link aggregation is not affected by the Ethernet frame type and packet length, and supports the aggregation of microwave links with unequal bandwidths, even when the Ethernet bandwidth of each link changes due to adaptive modulation, it can still be guaranteed The Ethernet bandwidth utilization of each link is basically the same.
Huawei RTN 300, RTN 900 series of IP microwave products fully support physical link aggregation technology. There are three types of physical link aggregation:
* PLA: The IF board (module) performs traffic distribution, which can realize load sharing of two microwave links.
* EPLA: Traffic distribution is carried out by the packet switching unit, and the maximum support for load sharing of four microwave links
* EPLA+: The packet switching unit allocates traffic to the dual-channel IF board, and the dual-channel IF board allocates the traffic to a specific IF port.
RTN 980 Nodal microwave products and RTN 980L Trunk microwave products support the aggregation of up to 12 links. The maximum service capacity of the aggregation group can reach 7Gbit/s, realizing fiber-level large bandwidth backhaul!
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