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excessive error on serial interface

one of our customer has three DMR(digital microwave radio) links which shares the same MUX of a 2M Nokia DM2 unit. the bandwidth are set at 128k,256k and 512k respectively.

we found excessive errors on all serial interfaces on 6 2600 routers connected on those 3 links. the interesting finding is only 75% of the bandwith is reported by the routers on all three links.

the DMR engineer suggests there could be a clocking issue between Cisco interface(x21 DTE) and the Nokia MUX.

but the problem didn't seem to happen with Cisco 2500 routers when the customer had a 128k DMR before those 3 links were put in place.

could you please advice what could be the reason?


Re: excessive error on serial interface

Generally there should be no difference

between the performance of the 2500 and

2600 routers. However, with X.21 there is

only has one clock, RXD. There is no

terminal timing as with the other standards,

such that X.21 really should never be

used above 64K because of this. At any

rate, I would treat this like a normal link

issue and first try loopback tests -

although I'm not sure that there is a loopback

definition for X.21 DTE devices - but you

can check with the carrier about that.

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