Common Workflows¶
There is an existing pyNTM training repository on GitHub that extensively covers common workflows with pyNTM.
pyNTM Training Modules repository module 1 covers what network modeling is, the problem it solves for, and the common use cases
Please see the pyNTM Training Modules repository module 2 for info and walk-through exercises for
- Directions on how to get started using pyNTM
- Setting up a practice/demo environment
- Finding Shortest Path(s)
- Failing/Unfailing Interfaces
- Finding traffic demands egressing a given interface
- Finding all ECMP paths for a specific demand
- Simple visualization exercise
Please see the pyNTM Training Modules repository module 3 for info and walk-through exercises for
- Adding a new Node
- Adding a new link
- Adding traffic to the traffic matrix
- Changing Interface/Circuit capacity
- Changing an Interface metric
- Working with RSVP LSPs
Please see the pyNTM Training Modules repository module 4 for info and walk-through exercises for
- RSVP LSP model data files
- RSVP types and behaviors
- Auto bandwidth
- Fixed bandwidth
- LSPs and Demands
- Getting an LSP path
- Seeing demands on an LSP
- Demand path when demand is on LSP
- Shared Risk Link Groups (SRLGs)
- Adding an SRLG
- Failing an SRLG
Please see the pyNTM Training Modules repository module 5 for info and walk-through exercises for
- How to create a visualization using the WeatherMap
- WeatherMap visual components overview
Checking Network Health¶
There are a some results to watch for in your simulations that will indicate a network augment or re-architecture of your existing or planned network may be helpful.
IGP routing is deterministic and much simpler to interpret; one obvious warning sign is over-utilized links.
It gets a bit more difficult with RSVP, especially with auto-bandwidth enabled, to determine if the network is under stress. RSVP auto-bandwidth behavior can be non-deterministic, meaning that there may be multiple different end-states the network will converge to, depending on the order in which the LSPs signal and how long each layer 3 node takes to compute the paths for its LSPs and a host of other factors.
With this being the case, there are a few behavior in the model to watch for when running RSVP that may indicate a network augment or re-architecture may be helpful:
- Large quantities of LSPs not on the shortest path
- LSPs reserving less bandwidth than they are carrying
- Some LSPs not being able to signal due to lack of available setup bandwidth in the path