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Hardware question for 4507R

Hi,

My core switch is a 4507 which I have numerous switches uplinking to.

Some of the downstream switches are connected to oversubscribed ports via trunk or etherchannel(with other oversubscribed ports). Will this cause a problem, or is there a better solution?

Is there a module for the 4507R which will give dedicated bandwidth to each port for uplinking purposes?

Thanks

Brian

3 REPLIES
Bronze

Re: Hardware question for 4507R

Oversubscribing ports is not a bad thing unless you require garaunteed bandwidth at all times.

So, if you have a 4507 with a 6 port 10 Gigabit module, the way the oversubscription works is based on port groups of 3, so the first 3 10 gig ports share a bandwidth of 24 gigabits, and the second set of 3 ports also share 24 gigabits of bandwidth.

As long as the average bandwidth stays under 24 gigabits per second per port, but if all 3 ports would need access to the full 10 gigabits at the same time, then you would have an issue. Most ethernet traffic is bursty and not all at the same time, so oversubscription can work well in most applications.

A situation where oversubscription might not be wanted is in a network with streaming video, say from cameras on a surveillence network, this creates a steady stream of traffic on the interfaces, so I wouldn't design a system like that to use oversubscription.

Now if you are using etherchannels to fill your oversubcription banks (so if I had 3 10 gig connections in the above example all etherchanneled together) then I would just consider that a 24 gigabit uplink because it's not shared by any other device, and you would actually be maximizing your bandwidth availability.

As for a module that gives dedicated bandwidth per port, that all depends on what type of bandwidth you are requiring, how many ports, supervisor module etc.

If you can fill in the blanks for me I can help you get a better idea of what you are needing.

1) How much bandwidth per switch are you "needing"

2) How many switches?

3) What kind of redundancy are you trying to achieve?

4) What supervisor module are you running and what IOS?

HTH,

Craig

Bronze

Re: Hardware question for 4507R

Also is your chassis a 4507R-E or just a 4507R?

And what slot are you connecting to? I know the 4510R-E chassis has less bandwidth available in the lower 3 slots.

Super Bronze

Re: Hardware question for 4507R

"Is there a module for the 4507R which will give dedicated bandwidth to each port for uplinking purposes? "

The WS-X4302-GB, WS-X4306-GB and WS-X4506-GB-T provide gig dedicated bandwidth to each of the card's ports. With some cards that oversubscribe bandwidth, you can also guarantee non-oversubscription or oversubription ratio by varying ports used on card. Table 2, in http://www.cisco.com/en/US/prod/collateral/modules/ps2710/ps5494/product_data_sheet0900aecd802109ea_ps4324_Products_Data_Sheet.html, provides bandwidth subscription ratios and see the "**" footnote.

"Some of the downstream switches are connected to oversubscribed ports via trunk or etherchannel(with other oversubscribed ports). Will this cause a problem, or is there a better solution?"

It might, depends how busy the uplinks are. If there's only transient congestion, might not be a problem. As noted above, you can adjust oversubscription on some cards, and/or vary number of Ethernet channels links to provide bandwidth needed to your downstream switches.

For example, user side doesn't tend to be a bandwidth demanding per port as server side. So, something like the WS-X4418-GB's two dedicated gig ports might be connected to server switches while the other ports are connected to user access switches.

PS:

The original 4500 platform is really inadequate for lots of high utilization gig since it only supports 6 GB per card slot. The later -E 4500, though, provides up to 4x the slot bandwidth.

If you want to consider a core bandwidth upgrade, you might also want to consider 3560-E, 3750-E and 4948 series.

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