Drawback when stacking could be scalability (there is always a maximum number of switches that could be stacked), but is a nice solution for a limited number of nodes. Of course, this is not at all an HA approach.
There is a network manufacturer that implements a couple of protocols that could be interesting for network redundancy and low-latency failover mechanisms, that can perfectly fit on that ring proposal you're doing. Those protocols are EAPSv2 (based in a set of rings) for L2 and ESRP for L3. Yet once again, propietary protocols, that's the drawback. Spanning tree has some caveats and could make you to increase the number of hops when communicating two distant leafs. In this case there are some vendor-specific spanning tree implementations (i.e PVST+, EMISTP, etc...) but also a number of "standard" Spanning tree standard implementations (for instance the first definition of STP in 802.1D and its successors 802.1w, etc....) Anyway, hop latency in Ethernet is most of times just peanuts in terms of latency compared to TCP/IP stack overhead... Other option could be not to impement redundancy but of course this depends on the criticity of your cluster.... 2007/7/11, Mark Hahn <[EMAIL PROTECTED]>:
>> my question is: do switches these days have smart protocols for mapping and >> routing in such a configuration? I know that the original spanning > > That's 802.3ad. Quick pointer: > http://en.wikipedia.org/wiki/Link_aggregation I don't think that's what I meant. imagine instead that you have 48pt GE switches, each of which has 4x 10G extra ports. now, take 5 such switches and fully connect them (each switch has a 10G link to each of the other 4 switches). I don't think 802.3ad helps here, since what you want is to _avoid_ a single spanning tree, which would necessarily have one root. 802.3ad is exactly the right thing if you simply want to stack two such switches and want 4x10Gb inter-switch bandwidth. I noticed that d-link appears to use 10G links for stacking, but has a route-discovery protocol that lets them structure the switches into a ring. I'm not sure they use this to reduce hop-count, though - perhaps just for reliability. _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
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