HELP! nm-8a/s Network module what speed?

[admin_2]

I received network modules nm-8a/s with 8 serial interface for syncronous links. I was asked to use these interfaces on dedicated leased line (CDN) at 384 Kbit/s.

On cisco web site i found that these interfaces can work up to 128 Kbit/s is that true? So they should not support higher rates, isn't it?

What seems strange is that these interfaces seems to work fine with a clock needed for a link of 384 Kbit/s with the router acting as DTE while the DCE provided by the ISP (with a V.35 interface) generates the clock. They work but i don't know what is the real speed 128 (nominal limit for the interface) or 384 Kbit/s (stated by the ISP on the DCE).

The serial interfaces itself can generate a max clock of 128.000 (acting as DCE) while seems to accept a clock rate of 4.000.000 when working as DTE, is that normal?

Should i change nm-8a/s with nm-4T?

Why the nm-8a/s syncronous interfaces are so slow?

Thank You very much for Your help

[zander13]

Change to NM-4T.

I just did a check on one of our 26xx router with nm-8a/s and it does NOT support clockrates above 128k.

http://www.cisco.com/en/US/products/hw/modules/ps2797/products_tech_note09186a00800a93f1.shtml

"The maximum speed is 115.2 kbps for async, 128 kbps for the sync external clock, and 125 kbps for the internal clock."

Hope this helps.

mips

[#3]

Ok this is the datasheet (max = 128 Kbps Syncronous mode) but the interface is working with a DCE generating a clock much higher of 128.000, this is what i can't understand...

It seems like the clock and andwidth supported are not directly related. This can be true on frame relay link (CIR and Burst Rate) an on channelize PRI but on a leased line it should not be possible!

Where am i mistaking?

Thank You