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Aggregators
============

Aggregation servers, or aggregators, are a key component in the
SD-WAN architecture. Aggregators split traffic bound for customers
into multiple streams for each leg and recombine traffic from each leg
before sending it on to its final destination on the Internet. This is
what allows SD-WAN to combine the speed of bonded connections,
even for a single download or upload, and to offer instant, transparent
failover when a leg goes down.

|image0|

Aggregators can be considered a type of router, since they route traffic
between the partner's core network and the bonders. In fact, they are
typically integrated into the dynamic routing configuration of the
partner network.

Aggregators should be connected to the Internet with a symetric
connection at least as fast as the speed of all the bonds assigned to
it. For example, if an aggregator has 10 bonds assigned to it, and each
bond has three 10 Mbps legs, the aggregator should have at least 300
Mbps connectivity to the Internet if it is not to be oversubscribed.

Aggregators are usually run as bare metal, for optimum performance, but
can also run as `virtual
guests <../nodes/supported-environments-for-nodes.html>`__. Aggregators
should be hosted as close to the bonders as possible, in order to
minimize latency added by the trip to the aggregator and back to the
bonder.


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.. |image0| image:: /attachments/1639347/11667736.png
