So when I’ve done most of my searching on these technologies so far, Google has auto-directed me to IOS XE when it comes to Cisco platforms. Looking at certification blueprints, it seems like the certification expectations are that you know how these technologies work across all three of Cisco’s primary network OSes (IOS + XE + XR).
I must fully admit my experience with the platforms that run these network OSes is pretty limited. My roles so far have mostly focused around specific cases where the network OS was not something I could control.
That said, I want to get a better understanding for when I should be leveraging a given network OS in a given scenario. I think I have a general understanding of the architecture of each of the Cisco-specific ones I’ve listed so far, but I feel like the hardware platforms these typically run on are going to have massively different specs.
And if my question seems super off-base, let’s direct the energy into what I should be asking! I feel like I’m almost in the “don’t know what you don’t know” category here, and every little bit will get me pushing in the right direction.
With the Catalyst 9k series, Cisco has been unifying many of their platforms. So IOS is pretty much just going to be IOS-XE, with NX for data center, XR for carrier, FXOS for Firepower, UCS for… UCS…
Carrier gear is almost always Cisco, Juniper, Ciena, Nokia, and increasingly Arista.
The technologies are pretty much the same, so the hardware and OS doesn’t really matter as long as it does what you want. EVPN is EVPN, regardless of if it’s a Cisco box or not.
The answer depends on scale and features.
“MPLS VPN” is only the tip of the iceberg to pick a platform/OS.
Think of how much bandwidth you need, how many VPNs, how many routes per VPN, if this is a PE or a P device, is this L3VPN, L2VPN, VPLS.
IOS-XE boxes are generally more for enterprise applications, few VRFs here and there.
IOS-XR are Service Provider oriented, where you need hundreds of VRFs on a PE for example. Or massive throughput requirements.
In the IOS-XR platforms there will be devices focused on aggregation vs core or even RR with a ton of RAM for millions of BGP routes.
Right, but from a practicality perspective, I realize that IOS tends to be run on Enterprise platforms, while IOS-XE tends to be run on service provider platforms. My original question is sort of Cisco specific and is basically “Do I really need to understand the full nuances of both?”
I do quite a bit of mentoring for others, and I don’t have much experience in the SP domain, so it would be nice to know whether the cert expectations line up with the community’s experiences and the platforms used.
Sort of… Interpretations of RFCs by each vendor really leads to different implementations and therefor varying feature support plus interoperability issues. Take VLAN-Based vs VLAN-Aware.
You’re thinking of IOS-XR as the SP-focused platform.
Majority of new Cisco gear aimed at enterprise customers runs IOS-XE. IOS (Classic) and IOS-XE are broadly interchangeable from a config knowledge perspective. You’ll notice more of the differences with troubleshooting or just minor feature support differences.
IOS-XE from a high level is Linux running IOS as a Linux process (IOSd) hence the strong familiarity you’ll feel switching between them. There’s a lot more under the hood differences but they mostly don’t matter at a 100/200/300 knowledge level.
Cisco would like to kill IOS classic but it’s just so much leaner for cheap low-power platforms. Service providers that are using it for CPE devices also don’t want to change so IOS is still being used on some new platforms (Cat1000 switches, ISR 900) though I’m sure it will be fully killed off eventually.
I have zero experience with XE, so this is a huge relief to hear, to be honest. I have been out of the enterprise game for over five years, and am definitely not using Cisco these days.
My experiences with XR were SP-focused, so you’re definitely solidifying something I suspected.
The traffic profiles for Ent/SP/DC are all going to be very different. I’m trying to make sure the people I’m working with understand some nuances that I’m still filling.