|
A more detailed discussion of the packets that routing protocols exchange may be found in [Goralski2009]_.
|
|
|
Another interesting utilization IPMininet_ is to explore the impact of a link failure. We start from a small variant of the above topology.
|
|
|
Another interesting utilization of IPMininet_ is to explore how routers react to link failures. We start from the same network as with the previous example and disable the link between ``AS2`` and ``AS3``. For this, we log on one of the two routers and issue the following commands.
|
|
|
``AS1`` is assigned ``2001:cafe:1::/48``
|
|
|
``AS2`` is assigned ``2001:cafe:2::/48``
|
|
|
``AS3`` is assigned ``2001:cafe:3::/48``
|
|
|
As in the previous examples, we create the routers and associate one IPv6 prefix to each AS:
|
|
|
As RIP messages are exchanged using UDP on port 521, we filter this port in the tcpdump_ trace. RIPng distributes the routes and our two hosts can exchange packets. The entire script is available from :download:`/exercises/ipmininet_scripts/ripng.py`.
|
|
|
A useful command to start is `show bgp summary` which provides a summary of the state of the BGP daemon.
|
|
|
Besides :manpage:`ping6(8)` and :manpage:`traceroute6(8)`, it is also useful to interact with the BGP daemon that runs on each of our routers. This is done by connecting on the Command Line Interface of the BGP router using telnet.
|
|
|
Draw the network and try to predict how it will react to a shutdown of any of the customer-provider links ?
|
|
|
Exercises
|
|
|
Exploring BGP
|
|
|
Exploring OSPF
|
|
|
Exploring RIP
|
|
|
Exploring routing protocols
|
Découverte des protocoles de routage
|
|
Finally, we can start the IPMininet_ topology and launch the daemons. The entire script is available from :download:`/exercises/ipmininet_scripts/ospf6.py`.
|
|
|
If you launch the script and immediately type ``ping6all`` to check the connectivity, you might obtained the following result.
|
|
|
In its output, we see that ``r1`` is attached to two different routers. Finally, the ``show ipv6 ospf6 database`` returns the full OSPFv3 database with all the link state information that was distributed by OSPFv3.
|
|
|
In these exercises, we mainly consider the ``show`` that extracts information from the BGP daemon. We type `show bgp` and press the `tabulation` key to see the available commands in the `show bgp`.
|
|
