What Does Running Multiple WANs Mean and How Do You Combine Them?
Running multiple WANs means connecting a network to more than one wide-area link at the same time. You do it for two reasons: to get more total bandwidth than a single link can provide, or to keep working when one link fails. How you combine those links depends on whether you control both endpoints. If you do, you can bond them into one higher-capacity path. If you only control your own site, you can load-balance or fail over across them, but you cannot merge them into a single faster connection.
Multi-WAN vs. a single WAN
A single-WAN connection is one link between your network and the outside world. Everything shares that link's capacity, and if it goes down, you are offline.
A multi-WAN setup uses two or more links. The links can be different technologies (for example, fiber plus a cellular backup) or the same type (for example, several T3/E3/DS3 circuits). What you gain depends on how the links are used:
- More bandwidth — traffic is spread across links so the combined throughput exceeds any one link.
- Redundancy — if one link fails, traffic moves to the others.
- Both — many designs do load sharing in normal operation and failover when a link drops.
Aggregation/bonding vs. load balancing
These two terms are often used interchangeably, but they produce different results.
| Approach | What it does | Result | Endpoints needed |
|---|---|---|---|
| WAN aggregation / bonding | Treats multiple links as one logical path | A single flow can exceed one link's speed | Equipment at both ends |
| WAN load balancing | Distributes flows or packets across links | Total capacity rises, but a single flow usually stays on one link | Can work from one side |
The key distinction is per-flow versus per-packet behavior. Load balancing typically assigns each connection to one link, so a single large transfer does not go faster. Bonding with fine-grained per-packet load balancing spreads even one transfer across all links, which is what actually raises the speed of an individual session.
Common use cases
Adding bandwidth between two sites you control. If you have two offices, each with its own Ethernet network, and multiple DS3/E3/T3 links between them, you can bond those links into one high-bandwidth path. E3Switch describes this as a Multi-TDM Gigabit LAN Extender: GigE in, multiple DS3/E3 links in the middle, GigE out, with per-packet load balancing over the bonded TDM links. It requires one unit at each end of the DS3/E3 transport.
Connecting a single site to an ISP. Here you have one location and an ISP router at the central office. This is a single-ended connection: one E3Switch unit at your site talks to the ISP over a DS3/E3 WAN. You are not bonding with equipment you control at the far end, so this is a different model from the two-site case.
Point-to-point LAN extension. Two distant customer locations, each with an Ethernet network, connected over intermediate DS3/E3 WAN transport. Again, one unit at each end.
Backhauling TDM traffic over Ethernet. Transporting DS3/E3 over an intermediate Ethernet network, for example backhauling cellular DS3/E3 over Ethernet radios, with one unit at each end.
Passive WAN monitoring. A WAN monitor with Ethernet output lets you passively observe a DS3 or E3 WAN and record or view the traffic, without a separate WAN tap device.
Practical considerations when choosing an approach
- Do you control both endpoints? Bonding and per-packet load balancing need matching equipment at both ends. If the far end is an ISP you do not control, you are limited to single-ended options.
- Do you need one flow to be faster, or just more total capacity? If a single large transfer must exceed one link's speed, you need bonding with per-packet balancing, not simple load balancing.
- Is the goal redundancy, bandwidth, or both? Failover designs prioritize staying up; aggregation designs prioritize throughput.
- What is the underlying transport? Multiple T3/E3/DS3 links behave differently from mixed Ethernet/ISP links, and the equipment must match the transport.
- What does each side need? Two-site bonding needs a unit at each end. Single-ended ISP connections need one unit at the customer site.
The E3Switch product line is described as plug-and-play, rack-mountable, and made in the USA, with a 30-day test drive. Model numbers are organized by application: 1x-DS3-... and 2x-DS3-... for LAN extension (or with DS3 replaced by E3), PPPOE-... for LAN-to-ISP, 1x-WANMON-... and 2x-WANMON-... for WAN monitoring, and WANoE-... for TDM over packet-switched networks.