Solved: benefits of adding a nexus switch to datacenter

prakavi · ‎09-08-2012

Hi,

We have two catalyst 6506 switches with 10 gb u plinks and around 120 edge switches cat 3750-x switches. Still the module on the core wheere servers are connected is 1000mbps port.Now if we induct a nexus switch to the datacenter what kinds of benefits we can reap In a virtulised environment as well as real environment?following are the some of the queries.

1- Can we reduce the number of edge switches? ( by virtual environment)

2- Inter operabaility between cat ios and nexus ios, how this will affect the environement

3- What will be the over all benefits ?

4- What are the cons of this induction ?

Regards

prakavi

Reza Sharifi · ‎09-08-2012

Hi Prakavi,

A FEX need to have a parent switch. The parent switch is usually a set of Nexus 5Ks or 7Ks. The FEX doesn't operate on its own and it is dependent on 5ks or 7ks. The image running on a FEXs is usually pushed to it via a 5k or 7k switch.

1- Can we reduce the number of edge switches? ( by virtual environment)

As also Leo and Jerry already have mentioned here, you only manage the parent switch. So, if you a row of 10 cabinets in your data center and have a FEX in each cabinet with 2 5ks (one in cabinet 1 and one in 10) you only manage the 2 5ks. It doesn't necessarily reduce the port count, because you have to connect a server to some kind of port, whether that port is connected to a FEX, 5K, 6500, 3750, etc... what it saves you is managing and maintaining fewer devices. Now if you virtualizes your servers and use for example UCS, IBM, HP, etc.. with VMs, that will reduce your port count significantly.

2- Inter operability between cat ios and nexus ios, how this will affect the environement

Yes, the Native IOS interoperable with Nexus OS very nicely. Once you start using Nexus OS, you will see that it is much easier to use than IOS.

3- What will be the over all benefits ?

4- What are the cons of this induction ?

For these last 2 questions you have to evaluate your environment, application and also cost, which is very important these days unless you have unlimited budget. As others also noted, the 6500 series has been around for a very long time and they are very feature rich. For example, if you are planning to add a Firewall Service Module to your design, than that is only supported on the 6500 and not the Nexus. So, is ACE module, WAN modules, etc...

Overall, Nexus switches are low latency devices with high backplane speed and a lots of througout for data centers, but one could argue that they could also be used as core devices. At the end it, all depends on your budget and requirement.

HTH

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Jerry Ye · ‎09-08-2012

1. It is possible but you have to understand what is supported with/by the FEX. Like you said, the Nexus is mainly for DC. FEX fabric interface has a 300m limit (from my memory), no 10mb support and no POE (since you said you have 3750X).

2. See 1.

3. See 1. Also, looks like you need L3. With the L3 module inserted into the N5K, this will reduce the number of FEXs to 8.

4. N5K support both 1G and 10G SFPs. And beside, if you use FEX, there are both models, 2248 supports 100/1000 and 2232 supports 1G/10G.

5. You have to decide if you want Nexus 7000 or Nexus 5500. The Nexus 5500 is less expensive when comparing to the Catalyst 6500.

Jerry

Sent from Cisco Technical Support iPhone App

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Reza Sharifi · ‎09-08-2012

Hi Prakavi,

As always you scores! well explained.But I have some more doubts to clear.From your explanations what I understand is that Nexus is mainly a datacenter switch.Still it can be used as a Core .But the flexibility of adding linecards is limited.

Maybe I did not clearly explain this in my previous post. With 5k and 7k switches you actually have more flexibility to add line cards. For example, with the latest release of Nexus OS (6.1), and Sup-2E,you can now have 48 FEXs per 7k. another word, imagine a chassis with 48 blades in it. Here is link for more info (see table-2).

http://www.cisco.com/en/US/docs/switches/datacenter/sw/verified_scalability/b_Cisco_Nexus_7000_Series_NX-OS_Verified_Scalability_Guide.html#reference_3AD0536C32FF4B499A0936409729951D

1-Can a FEX replace a stack of switches?If i have a stack of 5 switches over 15 floors can i replace the stack in each floor with a FEX?(irtulized environment)

You can, but remember if for example you are using POE on your 3750 switches, the FEX will not support that. You really have to look at your applications and requirement, functionalist, feature set you need before your replace your 3570s with FEXs.

2- Since we have cat 3750x swiitces on edge and cat6506 with 10g at the core the aggreagation is not bad.But if i can replace the 3750s with FEX really its helpful.

That is not bad design at all. If your core 6500 switches are not running in VSS mode and you are using spanning on your upliks from the 3750s to the 6500, You can convert them to VSS and use Portchannels to connect the stack of 3750s to the VSS pair. For VSS, you would need Sup-720-VS or Sup-2T. You would also need to purchase 6900 series or 6800 series card, but VSS would eliminate spanning tree, VRRP, HSRP, and much more overall throughput. You are basically using all your links from the 3750s instead of one forwarding and one booking.

3-Another question is that can i have a FEX each rack where cat3750s are deployed?

Not sure about this question but yes you can connect 3750s to 7ks or 5ks.

4-All the servers may not support 10G .So will it be an issue?

yes, not all servers need to be 10Gig. For example the 2248 FEX comes with 48 ports of 100/1000 copper.

5- Another option for me is that replacing the 1gb in the core where servers are connected with a 10 gb module. it will be less costlier than a NEXUS

Defiantly cheaper to buy 10Gig modules for existing 6500 and connect them.

If your servers have dual 10Gig uplinks, you can use VSS for the data center too.

Here is good doc to read on VSS:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/prod_qas0900aecd806ed74b.html

HTH

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Leo Laohoo · ‎09-08-2012

If your 3750X is your "top-of-rack" switch, then going to migrate/upgrade to Nexus is a no-brainer. Instead of managing each 3750X individually, you can deploy or use the Nexus 2K as top-of-rack switch. Management of these models are done by either the Nexus 7K or the 5K. By going down the Nexus solution, you manage only ONE switch for, say, 10 racks of switches.

If you are using 3K blade switches, Nexus also has two blades: B22HP (for HP chassis) and B22F (Fujitsu chassis). Again, the B22 family is managed by either the Nexus 7K or the 5K.

prakavi · ‎09-08-2012

Hi,

My question is that can I reduce the number of edge switches ?

Regards

Jerry Ye · ‎09-08-2012

Correction Leo,

B22 is for N5K only. There isn't any support on the N7Ks yet.

Regards,

jerry

Leo Laohoo · ‎09-08-2012

B22 is for N5K only. There isn't any support on the N7Ks yet.

Good point, Jerry.

mahmoodmkl · ‎09-08-2012

Hi,

Can u please let us know whether u r going for Nexuz 7K or 5K.

I can see the below benefits.

1.increase in performance.

2.You can have VDC's i.e.virtual swithces.

3.IOS and NXOS are fully interoperatable but command systax is bit idfferent.

4.U cannot reduce the number of edge switches.

Thanks

sean_evershed · ‎09-08-2012

If it was me I would be deploying at least 2 x Nexus switches in order to take advantage of vPC.

Cons:

- If you choose the N7K it draws lots of power and generates a significant amount of heat.

- In order to use many features of the Nexus you need to ensure you have purchased the correct license, for example MPLS or Advanced Routing.

- The Nexus does not support 100 Mb switchports. Many servers have management ports that only operate at this speed.

- The Nexus is a newer product than the 6K. Thererfore it's feature set is not as rich as the 6K.

Cheers

Sean

Leo Laohoo · ‎09-08-2012

The Nexus does not support 100 Mb switchports.

Yes it does. 2224TP & 2248TP/E support 100/1000BaseTx.

The Nexus is a newer product than the 6K.

Coming soon: Nexus 6K.

sean_evershed · ‎09-08-2012

What I meant to say was the N7K copper blades do not support 100 Mb rather than using a fabric extender.

Looking forward to the Nexus 6K

Jerry Ye · ‎09-08-2012

This is not true. The N7K M148 linecards support 10/100/100.

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/data_sheet_c78-574928.html

jerry

prakavi · ‎09-08-2012

Hi,

Great idea, But can I reduce the number of edge switches using VPCS?

prakavi · ‎09-08-2012

Hi,

kindly give the options if i give 7k and the same for 5k? My question is that whether I can reduce thenumber of edge switches by this implementation?

Regards

prakavi

Jerry Ye · ‎09-08-2012

Yes you can, if you are using FEX.

Regards,

jerry

prakavi · ‎09-08-2012

Hi,

Can you elaborate a bit how can I reduce the number of edge switches by using FEX(FABRIC EXTENDER)?

Regards

Jerry Ye · ‎09-08-2012

A FEX is centrally managed by the Nexus 5000. If you place a FEX as TOR, you can centrally configure all access ports via the N5K.

Regards,

jerry