Latency on E1 Lines

[lstegemann]

Hi,

Two 1841 routers are connected over 2 continents with an E1 line using VWIC-1MFT-G703 controllers. The configured channel-group generates a serial interface, which uses hdlc as the default protocol. I notice a standard ping round-trip-delay of at least 350ms between both routers. Is there a chance of reducing latency by using another L2-protocol?

Thanks,

Lothar

[mehrdad]

Hi,

There isn't any chance if you change L2 protocol.

is there any congestion on your links? if yes, you can implement QoS on your links.

Regards,

mehrdad

[lstegemann]

Hi mehrdad,

A relevant reducing of the latency occured two days ago without any configuration changes on my routers. I rather think of a changed WAN wiring.

Thanks for response!

Regards,

Lothar

[Georg Pauwen]

Hello Lothar,

use PingPlotter (www.pingplotter.com) to find out where the delay is occuring. Unless there are problems with the clock settings of your line, a delay of 350ms does not necessarily have to be unusual; in my experience, providers often classify ICMP traffic as best effort/low priority traffic.

Do you see any errors on your interface(s) (show interfaces serial) ?

Regards,

GP

[lstegemann]

Hello GP,

thanks for responding!

I may report you an event, that happened two days ago. Both routers detected a line outage for 10 seconds. Since then I see a ping-delay of about 210ms. My question to the carrier was being answered by: We have nothing done to the line, but the wiring of the WAN may have been automatically changed on an event of failure.

To your question: Yes, I see some errors on the serial interface of the router in the netherlands.

The statistics for the last two days:

3614 CRC, 744 frame, 30 overrun, 710 abort. The counters were cleared after the line outage. The remote site looks ok.

Regards,

Lothar

[amit-singh]

Hi Lothar,

If you have CRC errors that means the link is not not through completely and that's why there is a latency over the link. Try punching the cable at your end. If you have a telco Mux intslatted in your primises, then repunch the bcable on the MDF again. Try taking the local loop and remote loop from your IPS towards your premises and try pinging your local serial interface IP with large packet size. If you see CRC incrementing then ask your ISP to check the line using BERT meter for any type of errors in it.

regards,

-amit singh