On Tue, 2 Oct 2001, murthy kn wrote:
> >The hardware addresss for the bond are all identical,
> >so the arp table only has one entry, for the shared ip
> >address and hardware address.
> >
> >From an outbound point of view,
> > the target hardware is determined by the logic
> > you select, for example xor mode.
> >
>
> --------> My question is more intended towards a scheme like 2 linux
> boxes back to back connected (without a switch inbetween) and
> RR scheduling algorithm which can send packets of a single session over
> multiple cards.
>
> Let us consider the sending case (outbound packets).
>
> If my understanding is correct, ethernet cards have a fixed MAC address
> which we cannot change...
Incorrect. All cards have an Ethernet address stored in an EEPROM.
The driver reads the Ethernet station ("MAC") address from the card's
EEPROM when the card is first identified. Each time the interface is
started the driver copies the station address to the Ethernet chip.
The EEPROM contents may be permanently changed (see my diag programs) but
you shouldn't do that. One of the few valid cases is when you have a
software license keyed to a specific station address, and have to
replace a failed card. Another case is having a hot spare or duplicate
system where the requirement is exact compatibility.
> - so, when we say that all bonded cards have
> same HW address, I think we are talking about just the software state
> at the driver. Please let me know if I am correct?
Not only the software state of the driver, but also the hardware receive
filter register settings.
> One of the things I understand is that a card (hardware) doesnt grab a
> packet destined to some other card - for this the hardware will check the
> destination address on the card and with its own MAC address...
Correct.
> (which is determined at the time of Manufacture of the card and cannot
> be changed programmatically)
Incorrect. Modern Ethernet chips now copy the MAC address from the
EEPROM to the hardware Rx filter, but that's only to support
Wake-On-LAN.
Donald Becker becker@scyld.com
Scyld Computing Corporation http://www.scyld.com
410 Severn Ave. Suite 210 Second Generation Beowulf Clusters
Annapolis MD 21403 410-990-9993
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