mirror of
https://github.com/rtbrick/bngblaster.git
synced 2024-05-06 15:54:57 +00:00
Christian Giese
344 lines
11 KiB
ReStructuredText
344 lines
11 KiB
ReStructuredText
.. _ospf:
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OSPF
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----
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OSPF (Open Shortest Path First) is a dynamic Interior Gateway Protocol (IGP)
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widely used in large computer networks. It efficiently determines the best paths
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for data transmission, adapting to network changes in real-time. OSPF's link-state
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algorithm builds a detailed network map, optimizing data delivery and
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ensuring network stability.
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There are two versions of OSPF: OSPFv2 and OSPFv3. OSPFv2 is used for IPv4 networks,
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while OSPFv3 is designed specifically for IPv6 networks.
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The BNG Blaster can emulate multiple OSPF instances of both versions, OSPFv2 and OSPFv3
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(OSPFv3 is basically working but still under development).
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An OSPF instance is a virtual OSPF node with one or more network interfaces attached. Such a
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node behaves like a "real router" including database synchronization and flooding. Every
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instance generates a ``self`` originated type 1 router LSA describing the node itself.
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Configuration
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~~~~~~~~~~~~~
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Following an example OSPFv2 configuration with two instances
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attached to two network interfaces.
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.. code-block:: json
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{
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"interfaces": {
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"network": [
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{
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"interface": "eth1",
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"address": "10.0.1.2/30",
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"gateway": "10.0.1.1",
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"ospfv2-instance-id": 1,
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"ospfv2-type": "p2p",
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},
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{
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"interface": "eth2",
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"address": "10.0.2.2/24",
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"gateway": "10.0.2.1",
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"ospfv2-instance-id": 2,
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"ospfv2-type": "broadcast"
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}
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]
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},
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"ospf": [
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{
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"instance-id": 1,
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"version": 2,
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"router-id": "10.0.0.11",
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"hostname": "R1"
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},
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{
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"instance-id": 2,
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"version": 2,
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"router-id": "10.0.0.12",
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"hostname": "R2"
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}
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]
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}
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.. include:: ../configuration/ospf.rst
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The support for multiple instances allows different use cases. One example might
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be to create two instances connected to the device or network under test. Now
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inject an LSA on one instance and check if learned over the tested network on
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the other instance.
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Every OSPF instance can be also connected to an emulated link state graph loaded
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by MRT files as shown in the example below.
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.. image:: ../images/bbl_ospf.png
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:alt: OSPF
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.. code-block:: json
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{
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"ospf": [
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{
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"instance-id": 1,
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"version": 2,
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"router-id": "10.0.0.11",
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"hostname": "R1"
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"external": {
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"mrt-file": "ospf.mrt",
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"connections": [
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{
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"router-id": "10.10.0.1",
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"local-ipv4-address": "10.0.0.1",
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"metric": 1000
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}
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]
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}
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}
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]
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}
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.. include:: ../configuration/ospf_external.rst
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.. include:: ../configuration/ospf_external_connections.rst
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Interfaces
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~~~~~~~~~~~
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The BNG Blaster supports P2P and broadcast interfaces only.
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The following command returns detailed informations about all
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OSPF interfaces associated with the given OSPF instance (e.g. instance 1).
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``$ sudo bngblaster-cli run.sock ospf-interfaces instance 1``
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Neighbors
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~~~~~~~~~
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The following command returns detailed informations about all
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OSPF neighbors associated with the given OSPF instance (e.g. instance 1).
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``$ sudo bngblaster-cli run.sock ospf-neighbors instance 1``
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Database
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~~~~~~~~
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The BNG Blaster distinguishes between three different source types of
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LSA entries in the OSPF database.
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The type ``self`` is used for the self-originated LSA describing the own
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BNG Blaster OSPF instance. LSP entries of type ``adjacency`` are learned
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from OSPF neighbors. The type ``external`` is used for those LSA entries
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learned via MRT files or injected via ``ospf-lsa/pdu-update`` :ref:`command <api>`.
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``$ sudo bngblaster-cli run.sock ospf-database instance 1``
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The BNG Blaster automatically purges all LSAs of type
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``self`` and ``external`` during teardown. This is done by
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generating LSAs with newer sequence numbers and max age.
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Flooding
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~~~~~~~~
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The BNG Blaster floods LSAs received to all other active
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neighbors of the OSPF instance except to those with neighbor
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router-id equal to the source router-id of the LSA.
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LSA Update Command
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~~~~~~~~~~~~~~~~~~
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It is also possible to inject LSAs using the ``ospf-lsa-update`` :ref:`command <api>`.
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This :ref:`command <api>` expects a list of hex encoded LSA including
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the OSPF LSA common header (``| LS age | Options | LS type |``).
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``$ cat command.json | jq .``
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.. code-block:: json
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{
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"command": "ospf-lsa-update",
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"arguments": {
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"instance": 1,
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"lsa": [
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"000100050ac801000aff010180000001e7790024ffffff00000000140000000000000000",
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"000100050ac802000aff010180000001dc830024ffffff00000000140000000000000000"
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]
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}
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}
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The command ``ospf-pdu-update`` work similar to ``ospf-lsa-update`` expecting OSPF LS update
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request PDU including OSPF common header (``| Version | Type |``).
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.. code-block:: json
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{
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"command": "ospf-pdu-update",
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"arguments": {
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"instance": 1,
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"pdu": [
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"020400400101010100000000456e0000000000000000000000000001000100050ac80c000aff01018000012d13160024ffffff00000000140000000000000000",
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"0204004001010101000000003b780000000000000000000000000001000100050ac80b000aff01018000012d1e0c0024ffffff00000000140000000000000000"
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]
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}
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}
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LSA Update via Scapy
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~~~~~~~~~~~~~~~~~~~~
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The following example shows how to generate LSAs via Scapy
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and inject them using the ospf-lsa-update :ref:`command <api>`.
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.. code-block:: python
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import sys
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import socket
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import os
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import json
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from scapy.contrib.ospf import *
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def error(*args, **kwargs):
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"""print error and exit"""
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print(*args, file=sys.stderr, **kwargs)
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sys.exit(1)
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def execute_command(socket_path, request):
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if os.path.exists(socket_path):
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client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
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try:
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client.connect(socket_path)
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client.send(json.dumps(request).encode('utf-8'))
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data = ""
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while True:
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junk = client.recv(1024)
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if junk:
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data += junk.decode('utf-8')
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else:
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break
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print(json.dumps(json.loads(data), indent=4))
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except Exception as e:
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error(e)
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finally:
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client.close()
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else:
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error("socket %s not found" % socket_path)
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def main():
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"""main function"""
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socket_path = sys.argv[1]
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command = {
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"command": "ospf-lsa-update",
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"arguments": {
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"instance": 1,
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"lsa": []
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}
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}
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lsa = OSPF_External_LSA(type=5, id="10.200.1.0", adrouter="10.255.1.1", mask="255.255.255.0", seq=2147483649)
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command["arguments"]["lsa"].append(lsa.build().hex())
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lsa = OSPF_External_LSA(type=5, id="10.200.2.0", adrouter="10.255.1.1", mask="255.255.255.0", seq=2147483649)
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command["arguments"]["lsa"].append(lsa.build().hex())
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execute_command(socket_path, command)
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if __name__ == "__main__":
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main()
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MRT Files
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~~~~~~~~~
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The BNG Blaster can load LSA updates from a MRT file as defined in
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`RFC6396 <https://datatracker.ietf.org/doc/html/rfc6396>`_.
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.. code-block:: none
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0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Timestamp |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Type | Subtype |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Message... (variable)
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The message field contains the complete OSPF LS Update PDU including
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the OSPF common header starting with version field.
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Those files can be loaded at startup via the configuration option
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``"ospf": { "external": { "mrt-file": "<file>" } }`` or alternative
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via ``ospf-load-mrt`` :ref:`command <api>`.
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``$ sudo bngblaster-cli run.sock ospf-load-mrt file ospf.mrt instance 1``
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The following example shows how to generate such MRT file via Scapy.
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.. code-block:: python
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import struct
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from scapy.contrib.ospf import *
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def main():
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"""main function"""
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with open("ospf.mrt", "wb") as f:
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for i in range(10):
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lsa = OSPF_External_LSA(type=5, id="10.222.%s.0" % i, adrouter="10.255.1.1", mask="255.255.255.0", seq=2147483949)
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ospf = OSPF_Hdr()/OSPF_LSUpd(lsacount=1)/lsa
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pdu = struct.pack("!II", 0, 0) + ospf.build()
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mrt = struct.pack("!IHHI", 0, 11, 0, len(pdu)) + pdu
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f.write(mrt)
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if __name__ == "__main__":
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main()
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LSPGEN
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~~~~~~
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The BNG Blaster includes a tool called :ref:`lspgen <lspgen>`, which is able to generate
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topologies and link state packets for export as MRT and PCAP files. This tool
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is also able to inject LSAs directly using the ``ospf-pdu-update``
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:ref:`command <api>`.
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OSPFv3
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~~~~~~
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The BNG Blaster also provides support for OSPFv3, although it should be noted that
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its support, compared to OSPFv2, is still considered experimental.
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Conceptually, OSPFv2 and OSPFv3 function the same way in the BNG Blaster, and the
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basic configuration differs only in the version number. The control commands are
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also identical.
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.. code-block:: json
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{
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"interfaces": {
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"network": [
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{
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"interface": "eth1",
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"address-ipv6": "fc66:1337:60::2/64",
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"gateway-ipv6": "fc66:1337:60::1",
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"ospfv3-instance-id": 1,
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"ospfv3-type": "p2p"
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}
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]
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},
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"ospf": [
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{
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"instance-id": 1,
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"version": 3,
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"router-id": "10.0.0.16",
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"hostname": "R6"
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}
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]
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} |