At 07:26 AM 6/1/01, Burnham, Chris wrote:
>Does Gig Ethernet conform to the same minimum frame sizes as general
>Ethernet ie 64 bytes.If so how does it accomodate late collisions when
>running over distances of 2km or more.?
> Or is this not relevant as it will be point to point full duplex
and
>effectively collision free?????????
Good question!
Gig Ethernet is usually used in full duplex mode, but it can be shared.
With shared 10 and 100-Mbps Ethernet, the minimum frame size is equal to
the maximum round-trip propagation delay of the network. In other words,
the minimum frame size = slot time = 512 bits. Using this rule with shared
Gigabit Ethernet would have resulted in impracticably small networks.
Instead, the minimum frame is maintained at 512 bits (64 bytes), but the
slot time is defined as 4096 bit-times (512 bytes). Frames that are shorter
than the slot time are artificially extended by appending a
carrier-extension field so that the frames are exactly one slot time in
length. By increasing the minimum time a station sends, the standards can
support a larger maximum network topology.
Priscilla
>Please help it is giving me brain strain
>
>Chris Burnham,
>Systems Engineer,
>Delphis Consulting Plc.
>Tel: +(44) 020 7916 0200
>Mob: +(44) 07799403576
>[EMAIL PROTECTED]
>
>
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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