Subject: Re: FDDI

From: Peter Hunt <[email-masked]>
Date: Tue, 14 Jul 1998 09:39:09 -0700

Vivek,

	some FDDI devices can be programmed to accept frames with
MAC addresses other than the FDDI device's hardware address. This is done
by specifying a set of MAC address filters which describe the destination
MAC addresses of frames that the device will pass to the host.

	I think the feature was originally intended as a way to filter for
specific multicast frames, rather than putting the device in promiscuous
mode. But you can also add unicast MAC address filters to the set.

	The section recommends that when the router becomes vrrp master,
the virtual router's unicast MAC address should be added to the FDDI
device's set of MAC address filters, rather than reprogramming the
device's hardware MAC address (for the reasons you've stated).

	If the device doesn't support MAC address filters, then the device
should be put into promiscous mode, to accept all packets, and the filtering
should be done in software.

	Hope this helps.

	Peter.

---

From: Vivek Menezes <[email-masked]>
Date: Tue, 14 Jul 1998 14:17:08 -0700 (PDT)

> MAC addresses of frames that the device will pass to the host.

Hi Peter,
	Thank you for your prompt response. I had a question related
to how FDDI would treat a packet with a source address equal to the
virtual MAC address. If the master were to transmit a vrrp advertisement
using the virtual MAC address as the source. The question is how will this
packet
be taken of the ring. Will it continue to go around in circles
because its source address doesnt match any of the source addresses
of stations on the ring, or will it be dropped after sometime.

thanks,
Vivek.