The core skills of 4g wireless industrial router with Ethernet

At present, the market performance of core routers is very good. The system switching capability and processing capability of high-speed core routers are an important manifestation of their ability to be different from general core routers.

At present, the backplane switching capacity of high-speed core routers should reach more than 40Gbps. At the same time, even if the system does not provide OC-192/STM-64 interface temporarily, it must support this interface without upgrading existing interface cards and general components in the future. . In terms of device processing capability, when the system is fully loaded, all interfaces should be able to process short packets at wire speed, such as 40 bytes and 64 bytes, and at the same time, the switching matrix of high-speed core routers should be able to process at wire speed without blocking The exchange of all interfaces, regardless of the type of traffic.

1. Throughput

Throughput is the packet forwarding capability of the core router. Throughput is related to the number of core router ports, port rate, packet length, packet type, routing calculation mode (distributed or centralized), and test method, and generally refers to the ability of the processor to process packets. The packet forwarding capability of the high-speed core router is at least 20Mpps. Throughput mainly includes two aspects:

• Overall throughput
  The whole machine refers to the packet forwarding capability of the whole machine, which is an important indicator of the equipment performance. The job of the core router is to select the route according to the IP packet header or MPLS mark, so the performance index refers to the number of forwarded packets per second. The throughput of the whole machine is usually less than the sum of the throughput of all ports of the core router.
• Port throughput
  Port throughput refers to the port packet forwarding capability, which is the packet forwarding capability of the core router on a certain port. Usually two test interfaces at the same rate are used. Generally, the test interface may be related to the position and relationship of the interface. For example, the test throughput between ports on the same card may be different from the throughput value between ports on different cards.

2. Routing Table Capability

Core routers usually rely on established and maintained routing tables to determine packet forwarding. Routing table capacity refers to the limit of the number of routing table entries contained in the routing table. Since the core routers that implement BGP on the Internet usually have hundreds of thousands of routing table entries, this item is also an important manifestation of the capabilities of the core routers. In general, high-speed core routers should be able to support at least 250,000 routes, providing at least 2 paths per destination address on average, and the system must support at least 25 BGP peers and at least 50 IGP neighbors.

3. Backplane Capability

Backplane refers to the physical path between input and output ports. The backplane capability is the internal implementation of the core router. The traditional core router uses a shared backplane, but as a high-performance core router, it will inevitably encounter congestion problems. Secondly, it is difficult to design a high-speed shared bus. Therefore, the existing high-speed core routers generally Designed with interchangeable backplanes. The backplane capability can be reflected in the throughput of the core router, and the backplane capability is usually greater than the value calculated based on the throughput and the test packet length. However, the backplane capability can only be reflected in the design, and generally cannot be tested.

4. Packet loss rate

The packet loss rate refers to the proportion of data packets that cannot be forwarded due to lack of resources in the core router under a stable and continuous load in the data packets that should be forwarded. The packet loss rate is usually used to measure the performance of the core router when the core router is overloaded. The packet loss rate is related to the length of the data packet and the frequency of packet sending. In some environments, it can be tested and simulated after adding routing jitter or a large number of routes.

5. Time delay

The delay refers to the time interval from the first bit of the data packet entering the core router to the last bit being output from the core router. This time interval is the processing time of the core router operating in the store-and-forward mode. Latency is related to both packet length and link rate, and is usually tested within the core router port throughput range. Delay has a great impact on network performance. As a high-speed core router, in the worst case, the delay for IP packets of 1518 bytes and below is required to be less than 1ms.

6. Back-to-back frames

The number of back-to-back frames refers to the number of packets when the most packets are sent at the minimum frame interval without causing packet loss. This metric is used to test the core router caching capability. For a core router with wire-speed full-duplex forwarding capability, the value of this indicator is infinite.

7. Delay jitter

Delay jitter refers to delay variation. Data services are not sensitive to delay jitter, so this indicator is usually not an important indicator for measuring high-speed core routers. For services other than data on IP, such as voice and video services, this indicator is only necessary to test.

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