The key consideration when deciding on the right tool is whether the SUT needs to enforce at Layer 4 and above. Devices that do interact with Layer 4 streams, like firewalls and load balancers, require a transaction generator. That's because the SUT is interacting with the Transport layer stream, so that stream has to behave properly. It's also possible that the SUT will interact with the application, which can contain dynamic content--in this case, simulated traffic at Layer 4 and above won't be processed properly by the SUT because the simulated traffic expects specific responses to requests. Dynamic content or responses that aren't expected won't be processed or will be flagged as errors.
Traffic generators are bit blasters. They test performance and are good for testing Layer 2/3 devices. The advantage of traffic generators, like Spirent Communications' SmartBits and Ixia Communications' Chassis, is that they can create packet traffic to exacting specifications and send those packets at near line rate. For a recent review of 10 Gigabit Ethernet switches (see "Life in the Really Fast Lane,"), we used the Ixia 1600T to test performance and QoS (Quality of Service). By setting IP header fields, like IP address and ToS/DiffServe for QoS, we were able to exercise the 10 Gigabit Ethernet switches with high rates of varied traffic.
It's important to note that in addition to aiding performance testing, traffic generators provide reliable background traffic. In both the 10 Gigabit Ethernet switch tests and our review of midrange Fibre Channel switches, a traffic generator was used to stress the SUT with different types of traffic while a second tool measured performance. As with performance testing, the traffic generator must properly exercise the SUT; otherwise, the background traffic is useless.
A common mistake is to use a traffic generator to send UDP (User Datagram Protocol) traffic through a stateful packet-filtering firewall while using some other TCP-based tool to measure performance. The problem is that UDP traffic doesn't place the same load on the firewall as similar amounts of TCP traffic.
And though traffic generators often simulate TCP traffic with random initial sequence numbers, sequence number incrementing, source port generation and the like, the resulting traffic may not behave quite according to the TCP RFC. If the SUT actively tracks TCP state, you may find the tools don't perform as you'd expect.
Subsea cable alternatives can provide a level of comfort for those concerned about disruptions. Realistically, they will continue to play a small, but critical role in the short term.
Maintaining existing network infrastructures often incurs huge technical debt before newer technologies are adopted over time.
Amid ongoing regional uncertainties, telecom infrastructure in the Middle East has expand to include terrestrial low-latency network infrastructure, which offers resilience and agility in navigating political complexities without relying solely on undersea networks.
