WIC-1T Capabilities

[nohare]

Could someone please clarify for me the throughput capabilities of the WIC-1T Interface.

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I understand that the maximum speed supported is 2Mbit/s....does this mean in any one second, the interface can received AND transmit 2Mbit of data? If data arriving at a router was maxing out the interface, can the WIC-1T still transmit data at 2Mbit even though inbound is maxing out the interface? I guess what I'm trying to ask is whether the interface operates as a full duplex, bidirectional interface or not?

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[olorunloba]

Yes, the interface operates in full-duplex, bi directional mode.

What you should take note of is that if for example, inbound traffic is maxing out the interface, a ping across the interface would give high return time. This is because packets are still required to travel back and forth across the link. And with one direction congested, the communication will be impaired.

[nohare]

Thanks for the information.

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Could you provide an insight for this problem....

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During testing I simultaneously started two large FTP transfers (300Mb File), one from siteA to siteB and the other from siteB to SiteA across a 2mbit/s Frame Relay PVC. Using MRTG software, I am seeing siteA-router inbound traffic peaking at 2Mbit/s as expected (resulting in a flat graph line) whilst outbound traffic is unusually peaking at approx 650kbit/s (resulting in flat graph line). At SiteB-router I am obviously seeing the MRTG graph in exact reverse.

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I can't see why outbound traffic from SiteA is peaking at such a low throughput whilst inbound is at the expected 2Mbit/s

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It looks as though SiteA-router could be limiting the outbound data rate to 650Kbis whilst SiteB-router is sending at the full 2Mbits.

Any ideas would be greatly appreciated.

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Regards

[olorunloba]

Are you using the same kind of servers and FTP at both locations?. I feel the bottle neck might not be in the WAN link or interface but somewhere else. Try swapping the locations of the severs and see what happens. Also, please check your routing that you do not have assymetrical routing (i.e. forward and return path are not the same)

[jeiber]

Different operating systems have different default values in their implementations of the IP stack. Window size, MTU, etc., can have a significant effect on throughput. This extends up to the application level as well.

You may want to try using UDP in your bandwidth tests. TCP has 'flow control' built in, but UDP doesn't use this ACKnowledgement, so the transmitter can continuously send without waiting for an 'ok' from the receiver.

Here's a link with details. Good luck!

http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ip.htm#xtocid16

Jeff