The real 'investment protection' story of the Cisco 6500

Buyer beware: Upgrading could cost you more and kill performance.

As I am sure you all saw, Cisco recently announced the Supervisor 2T, extending the lifespan of the much loved platform. This continues Cisco's marketing message of investment protection around the 6500 ... the problem is, that the 'investment protection' story told here is simply false. The truth is that an upgrade to the Supervisor-2T in the manner described in Cisco's launch announcements would result in no bandwidth improvement and potentially over 7x performance reduction from the performance of the Supervisor 720 .

BACKGROUND: Cisco injects new life into Catalyst 6500 switch

Essentially, Cisco said that at $38,000, the Sup 2T is priced at one-third that of HP's A9508 switch yet is 3X the performance and supports 200+ features or services, claims Scott Gainey, Cisco director of marketing for Unified Access Solutions.  Gainey further said, "... a forklift upgrade to a comparable HP switch architecture would likely cost that customer more than $100,000, he said, and gives the customer only 720 Gbps of throughput."

Cisco Catalyst family at Cisco Live

Cisco Catalyst family through the ages as presented at Cisco Live.

Cisco expand on this further in its response to HP stating: "for 80 percent of our customers, migrating to the Sup2T really is as simple as a $38,000 list price upgrade."

So Gainey claims that ~$38k is what it will cost for existing 6500 customers to upgrade to the Supervisor 2T? This is in line with much of the messaging I have seen around the 6500, which clearly promotes the false idea that all a customer has to do is upgrade to the new management module and then they get to take advantage of the latest technology.

The statement also clearly implies that this upgrade will create performance that exceeds HP's limitation of 720 gbps. Simply upgrading to the Supervisor2T will not increase the performance levels of existing modules at all, in fact, it will substantially decrease the overall performance of the chassis from Supervisor 720 levels, unless every existing module is retrofitted with a new daughter card. To retrofit a fully populated chassis, the daughter cards alone would cost between $50-$105k list price.

So say you have a 6509, to get 720gbps of throughput, it would need to be fully populated with 67xx series linecards. So now say you want to upgrade to the Supervisor 2T, you get the new supervisors, plug them in, and distributed forwarding stops working since this feature is incompatible with the Supervisor-2T. This is a really big problem, as max system performance for the Supervisor-2T is 720mpps. System performance for the Supervisor 720 was 450mpps. But max system performance with a Supervisor-2T without distributed forwarding is only 60mpps. So before you plugged in the Supervisor 2T, your Sup720 may have had your system humming at 450mpps, but now it has been reduced to 60mpps.

But we can fix this, right? You can buy new distributed forwarding cards, and install them on the system boards of all your linecards. But once you shell out the $$$ and downtime required to do this, your system will still only operate at the same performance levels it did with the Supervisor 720. To fix the problem, Cisco offers two versions of the Supervisor 2T and the new Distributed forwarding cards, but even if you bought two of the cheaper version of the supervisor, and the cheaper versions of the distributed forwarding cards, it would cost you over 100k list, just to get it running at the Supervisor 720 level of performance.

To get the level of performance promised by the Supervisor 2T, you would need to replace all your linecards with the new WS-6908-10G, as there are no other linecards announced that work at the new performance levels. Cisco did announce the 68xx linecards, but these are simply re-marketed versions of the older 67xx linecards with a new daughter card that allows them work with the Supervisor-2T, but does not improve their performance. They still use dcef720 forwarding, and still have 40gbps bandwidth per slot, which is the same as the Supervisor 720.

And the performance numbers promised by the Supervisor 2T may not be as drastic as they seem. For example, the Supervisor 720 max forwarding performance is 450mpps, and while the Supervisor-2T claims nearly triple the bandwidth, it only claims a 37% improvement in packet forwarding to 720mpps. And the maximum 720mpps forwarding performance of the Supervisor-2T is based on a 6513-E, whereas the Supervisor-720's 450mpps could be achieved on 6509. When the Supervisor-2T is used with the 6509, max system performance is only 540mpps, only an improvement of about 16% in packet forwarding performance. The actual performance of the system is measured by combining the performance of the individual linecards, which grew from 48mpps for the Supervisor 720 to only 60mpps for the new 69xx linecards ... not nearly the performance improvement indicated by the marketing campaign.

I am not simply trying to bash this product, it may be a very good fit for your organization. My only point here is that I think consumers should know what they are getting.

The simple fact is that, dating back to the inception of the 6500, all linecards will always have the same speed connection to the switch backplane. Upgrading to a new supervisor has never improved the throughput of existing modules. So if you buy a Supervisor 2T based system with a first gen 61xx series linecard, which is supported, that linecard still has the same connection to the same classic bus that it did with the first generation of the 6500. The 67xx linecards that were released with the Supervisor 720 have a 40gbps connection to the switch fabric and use cef720 or dcef720 forwarding with or without the Supervisor 2T.

The only way you get the new performance is by buying all new components, and that is the real investment "protection" story.

Join the Network World communities on Facebook and LinkedIn to comment on topics that are top of mind.

Copyright © 2011 IDG Communications, Inc.