Redundancy on modular switches

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Apr 24th, 2007
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When is required to make a full redundancy for 4500R/6500 modular switches with chassis redundancy versus modules redundancy?

In my opinion it is necessary only if is required 24x24 ensuring. When there aren’t time gaps to shutdown equipment for maintenance jobs. Chassis redundancy is more expensive (may be not so much) and more complex in management. And this solution excludes some possibilities, for example Etherchannels uplinks to different modules in chassis. A 48 port 2960G/3560G switch can be connected with 4 ports Etherchannel to 2 different modules in 4500/6500 switch. We have got 12:1 oversubscribing and a good resiliency


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Amit Singh Tue, 04/24/2007 - 03:59
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Hello,


It depends on the criticality of the network. As you said rightly, if you have 24X7 envrionment and you cannot afford a downtime, then its better to go for chassis/module redundancy.


However if you have using the CPU and module level redundancy within the same chassis, I would suggest to go for an extra chassis as you only have to pay for chassis and power supplies only.Move you one CPU and each redundnat module to new chassis.This will make you network highly avaialble as the chassis was the single point of failure though you had the CPU/Module redundnacy. The chassis and PS will cost you only 10-15% of the overall solution that you will make.


You can also make the same ether-channel connectivity with redundant chassis. You can use PVST and MHSRP loadblancing for making both the chassis as active/active and have the load shared between them.


HTH,Please rate if it does.


-amit singh



pavelalex1 Tue, 04/24/2007 - 05:39
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> ether-channel connectivity with redundant chassis

Can you give more detail about this?

Amit Singh Tue, 04/24/2007 - 09:11
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  • Cisco Employee,

By that I meant that most of the switches like 2960's,3560's,3750's come with at 4 SFP ports and you can use an ether-channel using 2 ports to one chassis and using another 2 ports to a different chassis. If you have connectivity using Gig copper links, you can bundle the ports and connect to both the chassis. You can inturn connect both the core redundant chassis.


-amit singh

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