Ethernet or VG Anylan

[Pete Turnbull]

On Nov 22 2005,  8:18, Gil Carrick wrote:
> This offer on eBay is unclear to me. 8727096878
>
> It says Ethernet and it says VG AnyLan. I know VG AnyLan was supposed
to
> replace Ethernet, but I was not aware that anybody ever called them
both
> things.
>
> Anybody familiar with this product?

Not terribly, but enough to know that VG Anylan carries Ethernet
packets; it's only the physical layer that differs.  No carrier
sense/collision detect but instead it uses access rules called Demand
Priority to ensure there will never be a collision.  That,
incidentally, is why the switches are smart and not like ordinary
Ethernet switches.   Also VG Anylan uses all four pairs in the cable;
10baseT and 100baseTX only use two pairs (100baseT4 uses all four
though, and for the same reason that VG Anylan does -- more bandwidth
on inferior cable.  VG stands for "voice grade", ie Cat 3 or similar).
 Anyway, Ethernet packets are one reason a card can be both Ethernet
and VG Anylan.

Also most HP cards were made dual-standard -- one physical 10baseT
interface and one physical VG Anylan interface -- as a transition
mechanism.  Often they had two connectors , but sometimes just one that
can be configured or autoconfigures.  HP's website lists these as
dual-standard, probably by detecting signals on the second and third
pairs.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York