2821 bandwidth

[Aleksey Engalichev]

There are 2 offices, between offices a dedicated channel of 1 gigabit. The ends are cisco 2821. I can not use the 1 Gigabit channel for all power. Maximum achieves the transfer speed on the port 490-500 MB/s, although the port is 1 Gb at 2821.
Can you tell me why? This is the maximum that I can squeeze? I do not use NAT.

[Joseph W. Doherty · Accepted solution]

The 2821 is fast-path rated 170 Kpps for minimum size Ethernet packets, which supports about 87 Mbps. You're transfer rate will increase as the packet size increases, but the 2821 is not a (sustained) gig capable router (even though it has gig interfaces).

To support a gig rate (duplex?) you would want a performance upgraded 4451 or a entry ASR 1K.

[Aleksey Engalichev]

Thanks for the answer ! It's strange, then why the speed when copying files or the test (iperf) reaches 500Mbps on the cisco interface 2821

[Joseph W. Doherty]

Likely due to larger packet sizes.