{"id":3917,"date":"2014-07-07T20:21:55","date_gmt":"2014-07-08T00:21:55","guid":{"rendered":"http:\/\/blogs.n1zyy.com\/n1zyy\/?p=3917"},"modified":"2014-07-07T20:21:55","modified_gmt":"2014-07-08T00:21:55","slug":"long-lines-and-bandwidth","status":"publish","type":"post","link":"https:\/\/blogs.n1zyy.com\/n1zyy\/2014\/07\/07\/long-lines-and-bandwidth\/","title":{"rendered":"Long Lines and bandwidth"},"content":{"rendered":"<p>I was reading a bit about AT&#038;T&#8217;s former <a href=\"http:\/\/long-lines.net\/\">Long Lines<\/a> division, which for a period was a series of microwave towers placed around the country to allow long-distance calling. For example, <a href=\"http:\/\/long-lines.net\/places-routes\/1st_transcon_mw\/TelephoneNews-1948-02\/017.html\">here&#8217;s an article<\/a> from 1948 about the link between NYC and Boston. They had a series of <a href=\"http:\/\/long-lines.net\/places-routes\/John_Tom_Hill\/johntomhill.jpg\">distinctive towers<\/a>, with the odd stuff on top being highly-directional microwave horns.<\/p>\n<p>Eventually, demand exceeded the capacity of the microwave links, and <a href=\"http:\/\/long-lines.net\/places-routes\/maps\/FT\/1981LightGuide.html\">they began to run fiber<\/a>. (Interestingly, many of the old towers still stand, and have found other uses, for cell towers or regional radio traffic.)<\/p>\n<p>What&#8217;s interesting to me about fiber is that the capacity is seemingly infinite. While 100Gbps Ethernet is <a href=\"http:\/\/www.arista.com\/en\/products\/7500-series\">just emerging<\/a> (and presently only available, AFAICT, for links between switches), that&#8217;s grossly insufficient for, say, major Internet backbones. So places just multiplex many signals onto a single strand, known as <a href=\"http:\/\/en.wikipedia.org\/wiki\/Wavelength-division_multiplexing\">Wavelength-division multiplexing<\/a>, or WDM. Present capacity is now in the range of <a href=\"http:\/\/www.infinera.com\/products\/ILS.html\">terabits per second<\/a> on a single strand.<\/p>\n<p>Makes me wonder what things will be like in another 30 years.<\/p>","protected":false},"excerpt":{"rendered":"<p>I was reading a bit about AT&#038;T&#8217;s former Long Lines division, which for a period was a series of microwave towers placed around the country to allow long-distance calling. For example, here&#8217;s an article from 1948 about the link between &hellip; <a href=\"https:\/\/blogs.n1zyy.com\/n1zyy\/2014\/07\/07\/long-lines-and-bandwidth\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-3917","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/posts\/3917","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/comments?post=3917"}],"version-history":[{"count":0,"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/posts\/3917\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/media?parent=3917"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/categories?post=3917"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.n1zyy.com\/n1zyy\/wp-json\/wp\/v2\/tags?post=3917"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}