{"id":203,"date":"2020-09-26T13:27:14","date_gmt":"2020-09-26T13:27:14","guid":{"rendered":"https:\/\/dft.wiki\/?p=203"},"modified":"2026-06-09T14:52:35","modified_gmt":"2026-06-09T18:52:35","slug":"etherchannel-on-cisco-routers","status":"publish","type":"post","link":"https:\/\/dft.wiki\/?p=203","title":{"rendered":"EtherChannel on Cisco Routers"},"content":{"rendered":"

When the network grows and traffic increases, the trunks between switches start to become the weak point of the system.<\/p>\n

If this single cable breaks, all communication is lost, and all traffic shares the bandwidth of only one port:<\/p>\n

\"\"<\/figure>\n

Simply adding another cable does not fully solve the problem:<\/p>\n

\"\"<\/figure>\n

STP will automatically block one of the ports to prevent loops, so traffic is still limited to one port, with the second serving only as a spare in case the primary fails.<\/p>\n

EtherChannel creates one virtual interface made up of up to 8 ports. The resulting connection speed equals the sum of each port’s bandwidth.<\/p>\n

\n
\n

Switch1<\/p>\n

enable \r\nconfigure terminal \r\nno ip domain lookup\r\nline con 0\r\nlogging synchronous\r\nhostname Switch1<\/pre>\n<\/div>\n
\n
Switch2<\/p>\n
enable \r\nconfigure terminal \r\nno ip domain lookup\r\nline con 0\r\nlogging synchronous\r\nhostname Switch2<\/pre>\n<\/div>\n<\/div>\n
Set EtherChannel Static:<\/strong><\/p>\n
\n
\n
Switch1<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode on<\/strong><\/pre>\n<\/div>\n
\n
Switch2<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode on<\/strong><\/pre>\n<\/div>\n<\/div>\n
Set EtherChannel to negotiate via PAgP protocol (Cisco):<\/strong><\/p>\n
\n
\n
Switch1<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode desirable<\/strong><\/pre>\n<\/div>\n
\n
Switch2<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode desirable<\/strong><\/pre>\n
OR<\/p>\n
interface range g0\/1-2
\nchannel-group 1 mode auto<\/strong><\/p>\n<\/div>\n<\/div>\n
Set EtherChannel to negotiate via LACP protocol:<\/strong><\/p>\n
\n
\n
Switch1<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode active<\/strong><\/pre>\n<\/div>\n
\n
Switch2<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode active<\/strong><\/pre>\n
OR<\/p>\n
interface range g0\/1-2\r\nchannel-group 1 mode passive<\/strong><\/pre>\n<\/div>\n<\/div>\n
\n
\n
\"\"<\/figure>\n<\/div>\n
\n
No EtherChannel:<\/strong>
\n– Single port speed
\n– 1 spare port<\/p>\n
EtherChannel:<\/strong>
\n– Combined port speed
\n– No dedicated spare port, but if one link goes down the other carries the traffic.<\/p>\n<\/div>\n<\/div>\n
Mode Definitions:<\/strong><\/p>\n
    \n
  • ON – ON\n
      \n
    • Forces link aggregation without negotiation.<\/li>\n<\/ul>\n<\/li>\n
    • Desirable – Desirable\n
        \n
      • Both sides initiate negotiation and form the link.<\/li>\n<\/ul>\n<\/li>\n
      • Desirable – Auto\n
          \n
        • One side initiates negotiation and the other responds to form the link.<\/li>\n<\/ul>\n<\/li>\n
        • Auto – Auto\n
            \n
          • Both sides wait and will NOT initiate negotiation, so the link will NOT form.<\/li>\n<\/ul>\n<\/li>\n
          • Active – Active\n
              \n
            • Both sides initiate negotiation and form the link.<\/li>\n<\/ul>\n<\/li>\n
            • Active – Passive\n
                \n
              • One side initiates negotiation and the other responds to form the link.<\/li>\n<\/ul>\n<\/li>\n
              • Passive – Passive\n
                  \n
                • Both sides wait and will NOT initiate negotiation, so the link will NOT form.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
                  To verify the configuration on each switch, use the following commands:<\/strong><\/p>\n
                  show spanning-tree\r\nshow etherchannel summary\r\nshow interfaces port-channel 1<\/pre>\n
                  EtherChannel can also be used on access ports, but it is most commonly applied to trunk ports since they are the natural bottleneck for traffic.<\/p>\n","protected":false},"excerpt":{"rendered":"
                  When the network grows and traffic increases, the trunks between switches start to become the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-203","post","type-post","status-publish","format-standard","hentry","category-ccna"],"_links":{"self":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/203","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=203"}],"version-history":[{"count":7,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/203\/revisions"}],"predecessor-version":[{"id":5841,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/203\/revisions\/5841"}],"wp:attachment":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=203"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=203"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}