Consideration of 3750 vs 6500 at the access layer:
1) Are the 3750-E failure times slower than a 6500 with dual/SUP'? I'm talking about a master switch failure in a 3750 stack or a stacking cable failure and I need to apply a scenario to an IPT network where I want to avoid dropping calls
2) When a stack master fails, how many seconds does it take before the network is back up or does the forwarding simply continue on a sub-second basis, thus avoiding any call dropping?
3) In terms of QOS and other features, will the 6500's benefit me in any way over the 3750's again considering this is going to be an IPT enabled network.
1) Recovery is about the same but with the 3750-E, you are taking down devices connected to the master switch that failed while with the 6500, all modules continue to function with the exception of the failed Supervisor.
3) No, but it's more expensive. You need bigger power supplies, more expensive modules and you will pay a high price tag for software maintenance.
In short, 6500 is an overkill in the access layer unless you have money to burn. If you still decide to go with the 6500, give the PISA Sup Engine a look. It performs really well with QoS (it's done in hardware).
Ok and can I spec out a 6148 module to go with the SUP32s or these classic modules don't make sense and I should look to the 6548's which also support PoE. Is there buffers per port or shared bandwidth per 8 ports too little on the 6148's?
In the 3750's, QOS is done in software?
6548 is also a classic line card.
For fabric enable line card, you need to look into the 67xx line cards.
WS-X6548-GE-45AF is PoE enabled module with 1 Priority Queue, 2 Regular Queues and 2 Thresholds. It also provides 1.4MB per 8 ports
Usually, when a device does something in hardware, it's mentioned in the data sheet.
It seems QoS itself is not done in hardware but the ACL is. Therefore, it's 10 times faster than if done strictly in software.
And the WS-X6148A-GE-45AF seems to support 5.5 MB per port and 1p3q8t. It seems that this blade has higher capabilities than the WS-X6548-GE-45AF which only has 1.4mb per 8 ports or 0.175mb per port
I thought the 6548 modules were fabric enabled eg. the WS-X6548-GE-TX has a dedicated 8Gbps connection to switch fabric.
When considering 6500:
6148A = Classic
6548 = 8-gig fabric
6748 = 20-gig fabric
If you're looking at access layer, you're right to go with the Sup32 as it has the features of the Sup720 without the price or fabric overkill.
Of the cards listed above, only the 6148A and 6548 are compatible with the Sup32, as the 67xx cards require a Sup720. 6148A has better buffering capabilities, and will do PoE, so it is most often used with new Sup32 deployments.
Comparing 6500 to 3750E:
When it comes to redundancy, there is no question the 6500/Sup32 will offer better switchover times than the 3750E. 3750E switchover times are more comparable to RPR, while 6500 supports SSO/NSF, where the data loss is less than 1 second.
3750E however has better throughput than the 6500. Supposing you get dual Sup32-10G and a bunch of 6148A's, you'll end up with 4 10Gig line-rate ports, and a bunch of 8x oversubscribed Gig ports. A 3750E on the other hand offers full line-rate Gig/10Gig switching within a switch, and up to 64Gb switching between switches.
Another difference between the platforms is the access-layer features you can run. 12.2(33)SXH has made great strides in providing access-layer features previously only available in CatOS code, but 3750E is the platform that always has the new access-layer features first. Some of the more advanced routing features however are only available in the 6500 code.
Ultimately, the decision is best based on:
-How many Gig/10Gig non-oversubscribed ports do you need
-How fast do you need the switchovers to be
-What kind of features you need to run
i really appreciate the exhaustive response you've given. Two further questions if you don't mind:
1) I went through the release notes of 12.2(33)SXH. Can you give me 1/2 features you found were fantastic which are aval on the 3750E but not the 6500?
2) I thought failure times of the 3750E in case of master failure or cable failure was also sub-second. Have you heard differently? Also, have you heard of any compatibility problems with Avaya IP phones on these switches?