How Do Dual-WAN Routers Handle 2 IP Addresses?

How does a dual WAN router (Truffle Broaband Bonding Appliance) handle 2 IP addressesMushroom Networks provides dual-WAN and multi-WAN solutions for enterprises and therefore we commonly get asked about having 2 or more IP addresses from 2 different ISPs and how that will work. This is a very natural question to ask since within the dual-WAN router, you will be plugging in 2 separate ISP connections that are completely unrelated and don’t share any infrastructure from the ISP side. As an example, the WAN links might be an MPLS, DSL or a cable modem. They will naturally have different IP addresses (static or dynamic) assigned by the ISPs. How will the traffic, both inbound as well as outbound, be treated going through the dual-WAN router?

If the dual-WAN router supports an overlay bonding tunnel, then the Elastic Static IP at the Relay (where the bonding tunnel terminates) is also available for use by the office for both inbound and outbound traffic, since the bonded IP tunnel will be proxied through the Relay node that is terminating the bonding tunnel. As a matter of fact, this Relay node, when provided as a cloud service (see the picture), increases the reliability of the single, static IP dramatically, since it is hosted in a reliable high 9s data center and therefore will stay up and available as long as there is at least one WAN connection active at the office.

The Elastic Static IP can be used to reach the services on the LAN side of the dual WAN router, by coming through the relay in the cloud and going through the bonded tunnel. Similarly, the outgoing traffic will also traverse the bonded tunnel and go out through the cloud relay. This means for services running through the tunnel, session traffic can be routed around networking problems thereby providing an enhanced end-user experience compared to a single-WAN router.

Of course, a Broadband Bonding Service through a Relay is not always required. In fact, advanced dual-WAN routers should be capable of aggregating http downlink traffic without requiring a relay. For all other types of traffic, an aggregation with session-level granularity will be leveraged. This means that sessions not going through the bonded tunnel will go over one or the other WAN link for the multi-WAN router. It is important for the dual WAN router to have the capability to automatically handle sessions that need to be bundled together onto the same IP address, such as secure banking sites that will otherwise have more than 1 session. Without bundling these related sessions together, the separate sessions going over different IP addresses will break the application. This can be avoided by intelligent load balancing where such applications are kept on the same IP address, or by simply providing for the assignment of related traffic onto a desired IP address by the network administrator.

Either with or without the relay service, the multi-WAN router will enhance the resiliency and performance of the WAN for your office. In most of the cases, the cost of the bits delivered will be significantly lower, compared to a single premium WAN link as well.

Cahit Akin, CEO, Mushroom Networks, Inc. 

Mushroom Networks is the provider of SD-WAN (Software Defined WAN) and load balancing solutions capable of Broadband Bonding that enables self-healing WAN networks that route around network problems such as latency, jitter and packet loss.


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