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New Member

line protocol

Line up line protocol up,

In ethernet interface, what is this protocol?

Thanks..

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

line protocol

This protocol was a means of determining whether the interface was in an operational state (outbound data could be transmitted successfully). In earlier versions of Ethernet this protocol used an Ethernet keepalive message to determine the operational state. The keepalive was an Ethernet frame in which the MAC address of the interface was the source MAC (as expected) and was also used as the destination MAC. So in essence it was a frame sent to yourself. As long as the interface detected its keepalive messages the line protocol was up. If keepalives failed (the interface was disconnected from the media, the media was broken, etc) then the line protocol went down. As Ethernet technology has evolved (higher speeds, different media, switch connections, etc) the mechanics of the protocol have evolved but the purpose is still to determine the operational state of the interface.

HTH

Rick

4 REPLIES
Hall of Fame Super Silver

line protocol

This protocol was a means of determining whether the interface was in an operational state (outbound data could be transmitted successfully). In earlier versions of Ethernet this protocol used an Ethernet keepalive message to determine the operational state. The keepalive was an Ethernet frame in which the MAC address of the interface was the source MAC (as expected) and was also used as the destination MAC. So in essence it was a frame sent to yourself. As long as the interface detected its keepalive messages the line protocol was up. If keepalives failed (the interface was disconnected from the media, the media was broken, etc) then the line protocol went down. As Ethernet technology has evolved (higher speeds, different media, switch connections, etc) the mechanics of the protocol have evolved but the purpose is still to determine the operational state of the interface.

HTH

Rick

Hall of Fame Super Silver

line protocol

This URL has a discussion of the Ethernet keepalive that you may find helpful

http://www.cisco.com/en/US/tech/tk827/tk369/technologies_tech_note09186a008048cffc.shtml#t3

HTH

Rick

New Member

Re: line protocol

Is this keep alive (In old type of switches as you described in detail)  going out from the switch, reach other switch and come back?

Hall of Fame Super Silver

Re: line protocol

That type of Ethernet keepalive for designed for environments like the 10base5 and not so much a switched environment. In a switched environment the keepalive has the local MAC address as the destination MAC and since the switch would associate the destination MAC as being on this interface then it would not forward the keepalive to the other switch.

HTH

Rick

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