<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>My client has implemented a system in which 2951 routers with E&M cards have been used to extend what was essentially a 4 wire leased line circuit.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The system at either end of the IP cloud are connected using 4 wire modems. One site is primarily a transmit site and the other is primarily a receive site.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The E&M cards are configured as 4-wire Type 2 cards and the interface cables between the E&M ports and the modems are special-made Ethernet cables – standard RJ-45 jack on the Cisco end and going to bare wires to connect to the modems. The strands used or 3,4,5,and 6 (blues and greens). These correspond to the 4 audio wires of a card configured as a 4 wire Type 2 card.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Leads 1, 2, 7, and 8 (corresponding to E, M SG, and SB) are all unterminated.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The voice ports are also configured with connection trunk – pointing to each other – in effect creating a continuously open 4 wire audio circuit.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>When all equipment is turned on, everything is fine.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>However, when the receiving computer system (and its modem) are powered off – with the intervening Cisco routers and E&M cards remaining powered on – the transmitting side of circuit appears to receive messages looped back to itself (the system has a transmit and receive message counter – the receive message counter increases when there is no system on the other end doing any transmitting).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Another tech that I am working with has had commercial (non Cisco ) telco experience and he swears that the E&M card has a failover loopback mode. He has essentially convinced the client that when the E&M card does not “sense” that it is connected to anything, that it places itself into a maintenance loopback condition – thus producing the symptoms that are being seen.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have spent days searching and am unable to find any references to such a mode. I know of the “test voice port network/local loopback” command – I am referring to a process that happens automatically.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Anyone?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='color:black'>--------------------------------------------------------------------------------------<br>Dr. Jeffrey T. Girard (Jeff), PhD<br>Colonel, United States Army (Retired)<br>Owner, Network Engineer, VoIP Engineer - Wire Me Happy, LLC<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'>www.wiremehappy.com<br>(607) 835-0406 (home office)<br>(845) 764-1661 (mobile)<br>(607) 835-0458 (fax)<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>