Fanout cables

[Alan Smith]

Out of curiosity, how do people handle fanout cables in netbox?

(for example - plugs into a 40G switch single port and turns into 4 10G cables to plug into equipment.)

I am sure there is a better way to handle it than to make a "device" that has a 40G port and 4 10G ports on it.

Thanks in advance,

Alan

[Brian Candler]

On Monday, 11 January 2021 at 18:18:45 UTC alan....@nutanix.com wrote:

I am sure there is a better way to handle it than to make a "device" that has a 40G port and 4 10G ports on it.

There isn't really - the data model in Netbox is quite simplistic.

* An "interface" represents both a physical port, and a L1/L2/L3 interface.  You can't have 4 interfaces on 1 port, except as virtual interfaces

* A "cable" has exactly two ends, and each interface can only accept one cable.

* No modelling of SFPs or fibre pairs

I think your only real option, as you say, is to create 4 interfaces and plug four "cables" into them, as if it were four 10G interfaces (which in fact it is; they're aggregated into one port, but they work as four separate interfaces).

If you were using a QSFP to QSFP cable, then another option would be to create 4 virtual interfaces, as if they were vlans. However that won't work for a QSFP to 4 x SFP+ breakout cable.

[Justin Hammond]

So far I've been able to just create interfaces as they're named in the switch/router as physical interfaces without the base interface.  Most of the time that breaks down to the usual format - i.e., Ethernet49/1, /2, /3, /4, Ethernet50/1,/2,/3,/4, etc...

This seems to be one of those cases where you just find the way that makes the most sense to you and move forward with it.

[ralphn...@gmail.com]

Was about to run into the same dilemma end of this week. Justin's take is where my brain was heading, we will see if I can live with what it looks like in the end. Ultimately though, since there are 4 lanes in it no matter what, it's probably best to just go to the lowest common denominator anyways. Thanks Alan, haha! 

Chris

On Monday, January 11, 2021 at 10:18:45 AM UTC-8 alan....@nutanix.com wrote:

[Jeremy Stretch]

For anyone interested, there's some background about the challenge of modeling breakout cables on the NetBox wiki: https://github.com/netbox-community/netbox/wiki/Data-Model-Limitations#breakout-cables

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Jeremy Stretch

Founder

NetVerity, LLC