Only 50% bandwidth using 4 wire SHDSL back-to-back

[ingi]

Hi.

I have a 2811 ( CO ) with a 4-wire SHDSL interface connected back-to-back over a leased line to a 1841 ( CPE ). I have the line-rate set at 4608kbs and it works fine with no errors on the SHDSL interfaces.

I then connected my lap to the 1841 f0/0. I downloaded a file from the net and I got ca. 300kb per sec. I also downloaded a file from a server on the CO router site and got the same results.

So I'm only getting 50% of the bandwidth. The config on the routers is as simple as it can get for this type of a connection. No access lists or restrictions of any type.

I'm using PVC 2/100 and AAL5SNAP on the ATM interface.

Any idea why I'm not getting ca. 600kb download per sec?

Regards, Ingi.

[tekha]

I'm not sure what you mean by "with a 4-wire SHDSL interface", I believe the WIC-1SHDSL only uses 2 wires in the cable, not 100% sure. And where did you set the line-rate to 4608kbs?

What bandwidth do you see, when doing a "sh dsl int atm 0"?

According to this document (http://www.cisco.com/en/US/products/hw/routers/ps221/products_data_sheet09186a008008871a.html), the speed of SHDSL doesn't exceed 2.3 Mbps. (look for "G.shdsl WIC Business Class DSL Feature Highlights").

2.3 Mbps is roughly what you are getting, if "300kb sec" means 300 Kilobytes per second.

Are you using two WIC-1SHDSL cards?

[ingi]

Hi.

Thank's for your reply. I'm using the WIC-1SHDSL-V2, http://www.cisco.com/en/US/products/hw/modules/ps3129/products_documentation_roadmap09186a00802c4afc.html

S4_1841#sh int atm0/0/0

ATM0/0/0 is up, line protocol is up

Hardware is DSLSAR

MTU 4470 bytes, sub MTU 4470, BW 4608 Kbit, DLY 110 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 , PVC mode

23 maximum active VCs, 256 VCs per VP, 1 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 166

Queueing strategy: Per VC Queueing

5 minute input rate 36000 bits/sec, 2 packets/sec

5 minute output rate 36000 bits/sec, 2 packets/sec

343460 packets input, 451313839 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

219141 packets output, 68704282 bytes, 0 underruns

1 output errors, 0 collisions, 2 interface resets

0 output buffer failures, 0 output buffers swapped out

I connected two 1841 back-to-back using the Cisco SHDSL cable and got 480kb sec. transfer rate using the same config. So now I know it works.

Maybe it's the distance that is having this effect. The line is max 1.5 miles.

Regards, Ingi.

[tekha]

Hmmm, didn't know there was a V2 SHDSL card, and you are right, it supports 4-wire cables in order to, "provide a higher symmetrical bandwidth and longer reach than 2-wire G.SHDSL"

Did you configure both CO and CPE router like this http://www.cisco.com/en/US/tech/tk175/tk274/technologies_configuration_example09186a0080135834.shtml, notice that both are configured with dsl linerate AUTO.

Could you post the result of "sh dsl int atm0/0/0" instead of "sh int atm0/0/0"?

You should see something called Actual rate:, and then a number representing the line-rate negotiated between the 2 routers.

[ingi]

The command "line-rate auto" isn't an option on the routers, 2811 or 1841. I must enter the line rate value.

Attached is the output from "sh contr dsl 0/0/0" and the config. The DSL config is the same on both except for line-term, CO on the 2811 and CPE on the 1841.

Regards, Ingi.

[tekha]

There seems to a couple of errors on both lines on the CO end, perhaps you should try and set the line-rate at something lower then 4608 Kbps.