Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

NV Edge IRL Dimensioning

Use of nv edge can provide customers the ability to build resilient networks in a scalable way, maintaining simplicity on the control plane. It also allows to increase capacity of a given chassis making expansion an easier task. It introduces though the problem of dimensioning the IRL (Inter Rack Links) that connected the two racks on the nv edge pair. This paper will focus on this process.

Version history
Revision #:
1 of 1
Last update:
‎12-19-2013 08:26 AM
Updated by:
Labels (1)
New Member

Hi, gprueba:


Can you please confirm 100G IRL support starting with 4.3.0? According to NV Edge deployment guide:


  • Only Enhanced Ethernet Linecards (Typhoon) can be used for IRL. Support for 100G/40G IRL is supported from 5.1.3


I have an environment with XR 4.3.4, moving towards an NV cluster setup and would like to avoid an upgrade if possible.




Cisco Employee

Hi Carlos


CCO is the official documentation. Please refer to:


Data Links / IRL supported optics:

  • Optics support is as per LC support
  • 10G IRL support that started in Release 4.2.1
  • 40G IRL support that started in Release 5.1.1
  • 100G IRL support that started in Release 5.1.1




Best Regards,


Ki Na


New Member


I have issue with cluster ASR 9001 and 9010 

can we use single mode fiber as IRL because on Cisco DOC say

''SFP-GE-S and GLC-SX-MMD are the only Cisco supported SFPs that are allowed for all inter rack connections.''

and the booth SFPs mentioned are for Multi mode 


Cisco Employee

Hi Larbi, I assume you're building a cluster between 9001/9001 and 9010/9010 right?

as long as you have the supported optics, and this is key here, because there are no overrides possible as with linecard optics. this simply because the cluster EOBC ports are brought up by rommon, so rommon needs to have the right drivers for us to make the cluster peering happen.

The other thing is that when we're mixing SMF and MMF or optics for that matter, this *can* be done, but as everything with networking nothing is for free. Simply because single mode optics (laser) transmit at a MUCH higher power, multimode (led based sort of) will get blinded by it, so we need an attenuator to lower the light level. From MM to SM the sm receiving side may be too weak if the length is too long.

When running MM to MM over a SMF or SM to SM over MMF there are different things here too.

The "width" or radius of the glass so to speak of single mode is much smaller then for multimode. Multimode has shorter reach, and a smaller "core" or radius. Mind you that for reaching long lenghts having light "bounce" of the edges of the "cylinder" shape that the fiber is, will cause cross talk, data loss etc and what have you.

Now, here is the deal, TECHNICALLY it can work, but, and I hate to give you that "answer" it also "depends" on what the precise details are: distance, tolerance, quality etc etc etc.

I read a good analogy/write up once that I saved that I wanted to paste here, it is not mine, so wont take credit for this below, but it is a good detail, don't remember where I read that:

Consider single-mode and multi-mode fibres as water pipes with different diameters. Single-mode fibre has a diameter of 9.0 microns and multi-mode fibre comes in sizes of 62.5 and 50.0 microns.

The properties of the glass in the fibre determine the attenuation (signal loss) and the bandwidth (data rate), group delay (propagation delay v wavelength) and phase response.

You can join any two fibres together as long as the cores are in-line so that the signal is transferred from one cable to the other.

The differences in the properties of the fibres will affect the attenuation of the signal and limit the maximum distance, but will still permit a signal to be transmitted.

The wavelength of the signal is chosen to suite the properties of the fibre, eg:

A 1000LX GBIC uses a 800nM wavelength laser diode and over single-mode fibre will reach 10kM or more.

A 1000SX GBIC uses a 1300nM wavelength laser diode and over 50 micron multimode fibre will reach 550m.

A 1000SX GBIC uses a 1300nM wavelength laser diode and over 62.5 micron multimode fibre will reach 220m.

This does no stop you from mixing fibres or interfaces, just as you can mix the size of water pipes. You will suffer the affects of the mismatch between the fibres though!



New Member


for EOBC link we can use compatible SFP and replace SFP GLC-SX-MMD by SFP GLC-LH-SMD for single mode fiber 

now for IRL link I prefer to use XFP interfaces in MPA module : XFP-10GLR-OC192SR

XFP-10GLR-OC192SR: Cisco Multirate 10GBASE-LR/-LW and OC-192/STM-64 SR-1 XFP Module for SMF, low power.

Cisco Employee

sure thing that will work! for the IRL you can use any typhoon based linecard or interface with any supported optic over any applicable fiber (same story on that as above:) as you please.

so you can definitely use the XFP with the mod-X for that purpose no problem!