G.SHDSL Back To Back & HWIC-4SHDSL

Unanswered Question

Hi All,

I currently have a pair of Cisco 878's in a back-to-back configuration running absoultely fine with a line rate of approx 4Mbps. The 4-wire (EPS-8 baseband) circuit is provided by BT.

The ever increasing need for speed has sent me towards investigating the newer HWIC-SHDSL cards as they appear to work at an increased line rate of up to 11.3Mbps

I have configured a couple of spare routers (2811 and 1841) with the new HWIC's - both running updated IOS's (to support the new HWIC's)

c2800nm-adventerprisek9-mz.124-6.T6

c1841-ipbasek9-mz.124-20.T

With the new routers on the bench, using the exact same wiring configuration (wire-mapped using a Fluke) as the current 4-wire circuit the two routers synch and work perfectly on both pairs at 11.3Mbps which is great - happy days!

However , in swapping out the existing 878's for the new routers the circuit refuses to come up - put the routers back on the bench (same config) and it works ... I've even resorted to using a drum of cable between the routers (approx 125m) and they still synch...

I'm confident that the wire-map between the routers is an exact copy of the current live 4-wire circuit from BT (Fluke says so ) so is there some sort of distance restriction of these new HWIC's that is stopping them synching?

All help greatly appreciated ..

Stu

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Giuseppe Larosa Mon, 02/08/2010 - 02:56

Hello Stuart,

have you enforced a fixed line rate or are the two new routers rate adaptive ?

if you have fixed the line rate to 11.3 Mbps and line is too long for this to be set up you get no sync.

You can guess that your two sites are connected to a CO and the pairs are connected in CO so the total length is the sum of lengths between site1 and CO and CO to site2.

Hope to help

Giuseppe

Hi Giuseppe,

Thanks for the reply.

I should have mentioned in my post but obviously neglected to...

I've tried both fixed rates (as low as 1.5Mb!) and also leaving them to auto-train, (bearing in mind that the 878's synch on the same circuit at 4Mb 'fixed' no problem) - all to no avail. Even left the routers for 20 mins or so just in case it takes longer to synch over a greater distance but still nothing ..

Any other ideas?

Stu

Giuseppe Larosa Mon, 02/08/2010 - 07:07

Hello Stuart,

the details you have added leads again to some sort of cabling issue: they should have been able to sync in auto rate.

Looking at cabling info I see

RJ-45

RJ-45 straight-through

HWIC-4SHDSL

http://www.cisco.com/en/US/docs/routers/access/interfaces/ic/hardware/installation/guide/oview_ic.html

How have you prepared the transition to the two pairs provided by TELCO provider?

I remember some threads about problems of cabling with SHDSL v3

Hope to help

Giuseppe

Actions

This Discussion

Related Content