Add Network Reaction API

[svoropaev]

Please add a possibility to check how topology is changing in case of link(-s) and node(-s) failure via API. Typical usage:

• could we reload a particular router and what will be the impact:
  • Link over utilisation will occurs?
  • Network reachability will be broken? Some nodes will be isolated?

[Vadims06]

Thank you @svoropaev for your feature request. We need to think about the result output. Regarding Link over utilisation - what the best notation of link distinguishing? Source Node Id - Destination Node Id - Cost, i.e. 10.10.10.1_10.10.10.2_100 ? If more traffic will be routed over this link the positive integer will be, if less traffic - negative. Does it make sense? An example of the output. {result: affected_links: ["10.10.10.1_10.10.10.2_100": 500, "20.20.20.1_20.20.20.2_7": -20], isGraphConnected: True, disJoinedNodes: [] } disJoinedNodes (isolated nodes) is always empty if the Graph remains connected after the node failure. But if the graph will be splited into two groups, i.e. 2 and 200 groups, both groups should be printed in isolated node list, I think both lists should be printed?

[svoropaev]

Hi Vadim,

Regarding "Some nodes will be isolated?" request. I guess isGraphConnected: [True, False] is a minimum which should be returned. Not connected graph is a group of connected graphs. For me it would be enough to return the groups of connected graphs. For example we had a connected graph with nodes [N1,N2,...,Nn]. Without Ni [N1,N2,...,Nn] is separated to [[N1,N2,N5], [N3,N4,N8], [Nj,...,Nk]]. If we know how graph is separated we can predict business impact.

Regarding the "Link over utilisation". It is more difficult question. We don't know from OSPF database how more traffic each pair of nodes consume over the link(-s). And we don't know a real link utilisation. But we can calculate the worst case scenario. For example in worst case if link XXX failed or node XXX failed traffic over the link a-b will be increasing twice. But it looks like a difficult math task.

[Vadims06]

Hi @svoropaev , try vadims06/topolograph:2.25

Request:

import requests
from pprint import pprint as pp
r_post = requests.post('http://<topolograph-host>/api/network_reaction/node_failure/', auth=('   ', '    '), 
                          json={"graph_time": "25Nov2021_08h20m45s_7_hosts", "failed_nodes_list": ["10.1.1.2", "10.1.1.4"]})
pp(r_post.json())

Reply

{'affectedLinks': {'sptPathsDecreasedInPercent': {},
                   'sptPathsIncreasedInPercent': {'from': '10.1.1.1',
                                                  'to': '10.1.1.3',
                                                  'value': 60}},
 'disjointedNodes': [['10.1.123.23', '10.1.123.24'],
                     ['192.168.100.100'],
                     ['10.1.1.1', '10.1.1.3']],
 'isGraphStillConnected': False}```

[svoropaev]

Hi Vadim.

It looks good.

[Vadims06]

@svoropaev If you don't mind - I will close this feature request.