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2503 performance

I have an old 2503 and I want to connect 2 2Mb/s-serials and a 10 Mb/s Ethernet. Are there any performance constraints in the router if I would fully utilize the serial connections?


Re: 2503 performance

The 2500s are rated at 4400 packets-per-second (CEF) with 64 byte packets, which comes to around 2.2Mbits. As packet size increases the achievable packets-per-second goes down, but the maximum bandwidth one can push through a router tends to go up because the packets are bigger. A fairly limited number of tests with other router models showed bandwidth increasing by around 3-4x as packet size went from 64 bytes to 1500 bytes. That would put a 2500 at around 6-8Mbits with 1500 byte packets, but note that this is simply an estimate based on the performance profiles of some other routers.

Note also that these numbers are best case; i.e., CEF enabled, no performance-reducing features such as ACLs or NAT enabled, and so forth. If you're talking about full utilization of both circuits in both directions (full-duplex), that puts you at the upper end of the estimate (8Mbits) with full-sized packets. Average packet size is usually much lower on real networks, so the 2503 could end up being a bottleneck for you depending on your network's traffic profile. But as is usually the case, you can't be sure of anything until you actually try it.

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