W dniu 18.12.2024 o 20:38, Chicklon, Thomas pisze:
It is possible, or most likely very probable, that HMC to SE traffic goes out
to the switch and back. I really don’t know, nor have I had the network folks
trace it or asked IBM to verify this.
The point I was trying to make is that there is no dedicated cable that loops
between two ports on the HMAs so that the SE and HMC on that HMA can
communicate with each other. All cables that plug into the HMA have the other
ends of the cables all plugged into network switches.
A comment regarding no loop. It is 1000BaseT port. It is physically
impossible to connect two LAN cards without the switch.
Yes, for older 10BaseT or 100BaseT (10Mbps or 100Mbps respectively) it
was possible to use special "crossed" cable to connect Tx to Rx and vice
versa. However not for gigabit connection.
It is completely not mainframe-specific issue, it is just Ethernet.
Personally I doubt IBM would require external switch to connect two
physical LAN ports within single physical machine. My VirtualBox
machines also do not require physical ports.
However CPC1_SE to CPC2_SE connectivity do require some external LAN.
And it is suggested to have them within single IP network - that mean
connected with *no* router between (router, not switch). Reason - all
SEs within single network segment allow HMC or HMA to be "local". Remote
HMC is also possible but some features are lost.
--
Radoslaw Skorupka
Lodz, Poland
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