I'm running a basic Sup720 and want to purchase a mix of Gig copper linecards for the same chassis. I would like to use the 6748-RJ45 with a DFC daughter card. So far so good, if I add a 6148-RJ45, does that affect the distributed function of the 67xx card w/DFC? How about if I add a 6548 with a DFC3? I understand their different connections to the buses and fabrics, but I would like to know if they all revert t the lowest common denominator on the forwarding. Thanks in advance.
In this situation your 67xx line card with DFC will be OK. It will still make local forwarding decisions. If a frame enters the card that is destined for a port on the same card, it will locally switch it. If a frame enters the 67xx card destined for another fabric enabled card, such as a 6548, the frame will be sent directly to that card. However, if a frame enters the 67xx that is destined for the 6148 card, the frame will have to be sent to the Sup 720 fabric interface to be transferred to the 32-Gbps bus.
There is something that happens when you install a mix of fabric enabled and non-fabric enabled line cards in the same chassis (DFCs or not, it doesnt matter). The switch fabric will operate in Truncated Mode, which will lower the maximum throughput of the system from 30Mpps to 15Mpps.
See this for more info:
Hope this helps. Please give this post a rating ;)