Multi-termination Cable Trace: Interfaces are randomly swapped

[uedvt359]

NetBox version

v3.6.5

Python version

3.11

Steps to Reproduce

this is reproducible on demo.netbox.dev

1: Create 3 devices (names and interfaces obviously don't matter, but these are the ones in the screenshots):

• server (nms)
• switch-old (dist) with interface 65
• switch-new (spine) with interface 1:10

2: connect server to both switches:

• nms -> dist
• spine -> nms

3: do a cable trace

Expected Behavior

the interface of switch-old (dist) should be displayed above switch-old and same for switch-new (spine)

Observed Behavior

depending on the order in which the terminations were added on the multi-side, the interfaces might be flipped around. it can be "fixed" by removing one of the terminations, saving and re-adding it (if it doesn't work, remove the other one).

flipped:

after the remove-and-readd workaround:

https://demo.netbox.dev/dcim/interfaces/1802/trace/

### Tasks

[abhi1693]

I don't believe this is a bug just an nuance that there is no ordering in place to keep the display same every time the page is opened

[uedvt359]

look again closely at the two bottom items: dist is always on the left, but the associated interface changes!

[DanSheps]

I will try and take a stab at this this weekend

[DanSheps]

Took a look at this a bit, probably won't be an easy fix and might need a bit of a rewrite to the svg draw code.

[Moehritz]

I took a stab at this as well as #13922, they are related. I fixed both.

Currently device objects, terminations and cables are drawn separately with no linking them if they appear out of order, I built an extended testcase for that which highlights both issues:

(rear2 is actually connected to et1h1 of s02)

Updated Version looks like this:

If number of interfaces align, there will only be straight lines as before.

If it is okay for you I will submit my changes as a PR for review for you @DanSheps. Are there additional test-cases that I should do manually (verifying rendered SVG for some data) for changes in the renderer?

[jeremystretch]

Thanks @Moehritz, I'll take a look!