6509 10/100/1000 card vs New 3750

Unanswered Question
Oct 31st, 2008

I need to add multiple gigabit ports to my datacenter and am debating adding a 10/100/1000 card to my 6509 or purchasing a new 3750 switch. I've heard differing opionions and want some advice as to which is the best option. Thanks,

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Jon Marshall Fri, 10/31/2008 - 07:46


Very difficult to give advice without knowing

1) what the ports will be used for

2) How a 3750 would fit into your existing topology

3) Have you considered other switches eg. 4948 is a data centre switch designed to supply very low latency gigabit connectivity

4) Where these 6500's sit in your existing topology.

5) What other modules and supervisors you have in the 6500 switch because this will make a huge difference to the amount of available bandwidth.


kevin.joyce Fri, 10/31/2008 - 08:03

1) Connections to various servers within the room. All new servers need Gigabit connections.

2) Would uplink to the 6509 with a Gbit connection

3) Other options would be too expensive for our short term plans

4) There are 2 6509 switches at the core of our network in different buildings connected via fiber.

5) Data Center 6509 has the following cards:

a) SUP1A

b) SUP1A

c) 6408A (8 Port GBIC)

d) 6408A (8 Port GBIC)

e) 6348 (48 Port 10/100)

f) 6348 (48 Port 10/100)

g) 6348 (48 Port 10/100)

h) 6516 (16 Port 10/100/100)

Jon Marshall Fri, 10/31/2008 - 08:25

I agree with Amit in that if your plans are short term a 10/100/1000 module may be the way to go.

But you only have Sup1A's in your chassis. This means you only have a shared 32Gbps bus for all line cards. So there is a lot of contention already. You say that the 3750 will be uplinked to the 6500 anyway. I would consider looking into the 3750 if there was a lot of communication between the servers on the 3750 switch that does not need to go back to the 6500.

If there is very little inter-server communication then your bottleneck would be the 6500 switches.

Having said that with dual supervisors in the 6500 switches and presumably dual power supplies you have more redundancy that a standalone 3750.

It really does come down to the servers/traffic patterns and criticality of those servers.


Amit Singh Fri, 10/31/2008 - 08:09

In addition, adding the new switch will add another point of managability also another piint of failure in the network. Why do you want to add trobleshooting and manageability aid when you can simply put a line card in Cat6500.

kevin.joyce Fri, 10/31/2008 - 11:17

Excellent, thank both of you for your information. I will add the 10/100/1000 48 port card to the 6509.

Joseph W. Doherty Fri, 10/31/2008 - 12:45

Instead of adding an old series 6500 10/100/1000 line card to your 6500, and instead of using a 3750, you might consider increasing your port count by using a gig L2 switch, such as a 2960G switch. Unless you expect to have high traffic between ports of the external switch, or route between VLANs, even the 8 port 2960Gs might be an option. (The 8 port models would help preclude high oversubscription of the uplink ports for server usage. Smaller incremental port expansion, lowers cost to have spare on-hand, and likely useful if you upgrade core switch later on.)

If you see the need to route, outside of the 6500, then the 3560/3750 series would be of interest. If you want lots of ports in one logical device, and with some additional redundancy, then the 3750 would be of interest.


From a raw performance perspective, I believe the 2960G/3560G/3750G models have both a higher Mpps and more internal bandwidth than your existing 6500. The 3750 stack bus is not quite as fast as the 6500 bus, although the 3750-E StackPlus should better it.

Oh, also on the issue of redundacy, an external switch can fail; so can a 6500 line card. (Another reason less expensive L2 switch, for on-hand spare, might be of interest.)

Joseph W. Doherty Fri, 10/31/2008 - 15:04


Forgot to add to my prior post, considering what your 6500 is now equiped with, replacing the whole chassis with a 3750 or 3750-E stack is a possibility. If you were considering that as an option, then starting with one or two 3750Gs to provide gig server ports might make more sense than using L2 or 3560G switches. If you believe you might upgrade your 6500 chassis, then less expensive L2 switches, to "fan out" some of your existing gig ports, likely makes more sense.

I see the only 10/100/1000 card you have is the 6516. This, and the other x65xx cards are really optimal for sup2 with SFM (or sup720). For your sup1a (or sup32), your 1st choice is likely to be the WS-X6148A-GE-TX. Depending how many ports you need, you could also swap out the 6516 with one of these.


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