NEXPEED NBG440 User’s Manual
NexComm Systems, Inc. 90 PAGE
Load Balancing and Line-Backup
NBG440 that has more than one WAN port offer the functionality of Load Balancing so it enables
to increase the bandwidth.
Load Balancing
There are a few methods to increase the bandwidth in the case of more than 1 channel.
Firstly, combining multi-channel by the use of an H/W logic to form a logical channel.
The typical examples are IMUX and IMA(Inverse Multiplexing over ATM). This
method preserves packet order by distributing the load properly in the viewpoint of each
link. In this way, the bandwidth can be increased but the disadvantage of this method is
the requirement of additional H/W logic.
Secondly, MLPPP(Multi Link PPP) method of combining multi-channel into one logical
channel by the use of a S/W. The MLPPP method provide the same functionality as
IMUX or IMA. There is no need for additional H/W but it induces more loads to CPU.
Lastly, the load balancing method makes a use of a S/W just like the MLPPP method.
The difference between the two methods is that it regards each of the whole channels as
an independent one. This method distributes the load properly according to the induced
load. So it puts less burden on the CPU.
The NBG440 router supports the Load-Balancing using a S/W :
The term ‘Load balancing’ describes functionality in a router that distributes packets
across multiple links based on layer 3 routing information. The kernel part of the load
balancing is to configure the multiple paths to the same destination. Each of the paths is
given a weight according to the
metric
parameter. When these values are equal, the data
is transported depending on the ‘cost’. Metric is used at the time of setting the
redundancy route and set ‘1’ as a default if not defined.
