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Full / Half Duplex

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pd123

Programmer
May 22, 2001
48
GB
I have seen the term full / half duplex used quite a bit when looking up problems regarding networking Solaris.

Could someone explain what the difference is? Is one quicker than the other? Which one should I be using?

Many Thanks,
pd123
 
Full Duplex can both send and receive at the same time, besides doubling the traffic, it also tends to dramatically reduce collisions. You need switches to network with full duplex.

Half Duplex allows the device to send or receive but never both at once. Hubs usually only allow half duplex.


the major hiccup is if one side of the wire decides to be full and one side decides to be half, the throughput is very reduced. (different ports can be different, just not different ends of the same port) this happens with old Solaris OSs (2.4 and 2.5) I tried to remain child-like, all I acheived was childish.
 
If you run 100Mb Full Duplex you will need to set this in /etc/system to prevent autonegotiation. The switch port will need to be locked to 100Mb Full Duplex as well.
Sun systems and some switches do not autonegotiate the same way so this does not work.
Add the following to /etc/system
set hme:hme_adv_autoneg_cap=0
set hme:hme_adv_100T4_cap=0
set hme:hme_adv_100fdx_cap=1
set hme:hme_adv_100hdx_cap=0
set hme:hme_adv_10fdx_cap=0
set hme:hme_adv_10hdx_cap=0
 
While you MAY need to do so, I have had wonderful experience with autonegoitiate with Solais 2.6 and up and Nortel 450s and 1200s, only 2.51 and lower had issues with my gear. I tried to remain child-like, all I acheived was childish.
 
Me also Mike, I had solaris 8 autonegotiate with a cisco switch and deciding to use half duplex.
Ged Jones

Top man
 
What's network card did you use for your solaris ?
Because I also got same problem with Intel NIC connect to Nortel switch,but I used Linux (Intel) and Novell(Intel).
If I used 3com NIC, I didn't have this problem.
I suspected the Network card can't sync with the switch (autodetect speed).
 
I use Sun's hme0 sbus cards, and they work fine, on PCs they use 3com cards, but not on solaris I tried to remain child-like, all I acheived was childish.
 
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