I have 4-5m PPS and ~12Gb bps and around 650 interface vlan and each vlan has 3-4x prefix such as /29 or /28 and i have 6-7 bgp session with no full table and around 2000 IP routes with around 3000 mac address , as i read nexus 3k datasheet and 5k datasheet it seems both can handle my traffic, but i do not know what is their real difference , and does n3k really is able to handle these traffics ? my exact 3k part number is N3K-3064PQ-10GX and if i want to use N5K i want to use N5k-5548UP-AF with N55-D160L3-V2 Layer 3 module. and i have that N3k in stock but if i want to use n3k i should purchase it so i like to save my money :P i will appreciate if anyone can guide or help me. Thank you.

  • As others have said, the n5k is not so string in the L3 world. Your 3064 may physically support everything you want to do, but it's not ideal. Maybe look at the n6k. If you have the budget and space, n7k. Or a n9k, but they (9300) have a long list of restrictions as well. – Ricky Sep 26 '20 at 16:14
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Be sure to understand the limitations of the N5K


That document ist for NXOS 7.3.0, but I don't think that these figures grew all that much on the way to 7.3.3.

Most important:

  • only 256 SVIs
  • only 7'200 or 14'400 dynamic routes (depending on version of the L3 card)
  • only 160Gbps of L3 throughput (see below)
  • can't configure routed ports (if memory serves right)

And then I have a fragement of memory of throughput rating dropping from 960Gbps to 240Gbps with the L3 card - but I'll try to find better info source for that.


So it's only 16x10G in/ouit of that L3 Daughter card.

Source: http://n-sistem.net/pdf/Architecture_Nexus5000_5500_2000.pdf Which is from a presentation at Cisco Live 2011 in Las Vegas (Session BRKARC-3452, Cisco Nexus 5000/5500 and 2000 Switch Architecture) from where I'll try to quote:

Layer 3 Forwarding Engine connects the the X-Bar via two UPC (160GBps)

And this diagram:

Nexus 5500 internal Architecture with L3 daugther card


Hence: The N5K is a very fine L2 switch with can be persuaded to do "some" L3 work. A full-fledged L3 switch, it is not.


Start from this page for the 5500's verified scalability and this for the 3K.

In short (...and as mentioned above) the L3 switching module on the 5500 is basically a router on a 16x10GE switch. The verified scalability guide calls out a 256 SVI limit. If your requirement for 650 'interface vlan' maps to SVI's then the 5K is likely not fit for purpose. The 5500 is, however, capable of supporting up to 4000 active VLAN's (...once again reinforcing that the 5500 began life as a competent L2 switch).

The 3064 can support 1024 SVI's, but the platform can only support 507 active VLAN's concurrently (assuming MST). Again, if you're defining 650 SVI's then this would tend to imply defining at least 650 VLAN's and is over spec for the switch. The 3K was built as a low-cost top-of-rack switch with (old) merchant silicon that could support L3 and decent throughput but wasn't intended to do any kind of L2 heavy lifting.

If I were forced to choose, I'd use the 5500 as an L2 switch to terminate other switches and deal with trunking, whatever flavor of STP, etc and then use the 3064 via an LACP bundle to handle L3.

That said, this is a no-win situation in terms of real operations. Both platforms are old. The 5500 hit end of software support in May of 2020 and is full LDOS (last date of support) in 2024. The 3064PQ was announced EOS in 2016 and hits full LDOS in 2022.

Basically the point is that neither switch should be newly deployed into any kind of production role. Beyond any question of scalability they're both going to soon hit a point where there aren't even security updates, much less bug fixes or useful enhancements. Both platforms have been in the process of active retirement for years at this point.

If these are your two options, find a third.

  • i have N55-D160L3-V2 for my n5k-5548up-af and i have create 280x interface vlan with different IP address on them and all of them are up and routes are available in show IP route, do i understand svi correctly? it N55-D160L3-V2 cause that i can have much more vlans ? – Blackmetal Sep 27 '20 at 8:41
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    SVI = Switched Virtual Interface, so basically any time you have interface vlan xxx and an L3 definition you're using one of the 256 interfaces that the L3 card supports. Would it work at 280? Maybe, but it's outside what's been tested and certified for that platform and you could hit anything from a software limit to unexpected (and potentially catastrophic) behaviors. The 5500 was a decent choice as an L2 aggregation platform but the L3 module was kind of an afterthought (nb - the 56xx has native L3 routing, as do most modern DC switches). – rnxrx Sep 27 '20 at 21:01

The N3k is suitable for your application.

The main advantages of the N5k are the ability to use fabric extenders (very similar to stacking tbh) and to combine fibre channel & Ethernet for networks which have legacy SAN needs, as well as some models having expansion slots. However, it is a more complex product line; and doesn't offer very large MAC & layer-3 tables as compared to many other modular multi-layer switches.

You didn't describe your plan for aggregating the 650 interfaces/ports but I assume you are confident in that aspect of your plan.

  • we have 20x full rack in a datacenter and we are offering colocation services , and each interface vlan may have 3-4 x prefixes such as /29 or /28 or ... , but i just create 350x interface vlan on a n5k-5548up-af and assign 1x /24 to each vlan , i can see all vlans are up and from a server behind the router i can ping their gateway and in show IP route i can see their routes, and as i read in that n5k guide it says the verified limit is for that time that all features are enabled! i just enable 2-3 feature – Blackmetal Sep 27 '20 at 9:21
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    Just because you can see 350+ SVI's up doesn't mean that they're going to function as expected. You're almost 50% beyond what Cisco's QA ever tested and certified for that platform. It might work perfectly. It might crash randomly. It might cause completely unpredictable behavior. If these services are even faintly important you'd be better served looking at a platform that's both supported and within the vendor's listed limits. – rnxrx Sep 27 '20 at 21:06

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