IGMP - Telecom UA 2019-20

Stan Schepers & Luckas Declerck (V1)

Luckas Declerck (V2)

This project implements IGMPv3 on the Click Modular Router. The solution is interoperable using the given reference platform. The implementation can executed by running sudo ./start_click.sh in the click/scripts folder. Make sure to comment out the elements in this file when running both this and the reference implementation.

All the checksums of in- and outgoing IGMP packets will be checked, as well as the the checksums of the IP headers (as a seperate click element)

Changelog V2

• Packets weren't forwarded to client elements itself (arpq missing)
• Packets were sent to wrong MAC address
• IGMPGroupMembers (clients) didn't internally check if they are subscribed to a resource when they got a packet from it. (filter)
• The TOS-byte is added to the packet header
• Extra tests and scenarios were added

Basic Usage

Clients can join/leave multicasts group by calling the following handlers: write clientXX/igmp.join [multicast IP] and write clientXX/igmp.leave [multicast IP]. These lines can be executed in the telnet panel telnet localhost {portnumber} where portnumber is:

• client21: 10003
• client22: 10004
• client31: 10005
• client31: 10006

The router will handle these state changes internally, output will be visible in the console or in the .pcap files.

Extra Implementation

• A client can join multiple multicast addresses (tested in worst_case_scenario)
• Checksums of the IGMP header, IP header and UDP header will be checked (tested in worst_case_scenario)
• IGMP Packages with an unknown type (other than Query/Report) will be silently ignored
• Leaving unjoined resources will be silently ignored
• Joining nonexisting resources will be handled correctly by the router
• Handler for simulating a client that won't respond

Scenarios

Our project comes with 2 scenario's: the happy_day_scenario.sh end the worst_case_scenario.sh. In the first one, the given scenario (blackboard) will be executed. The second one will stress-test the router and clients by executing the following:

• Client joins a server that does not exist
• Client leaves a group where he's not joined to
• Client joins two times consecutively
• Client will be killed, router must stop forwarding after timer has passed Just run these test anywhere on your PC while the clickfiles are running.

Extra Handlers

We used the given handlers of the reference implementation to test our created elements. But for some specific reasons we created our own.

• a Kill Client handler. This handler will can be called to simulate a dying client, which will result in not answering to the general queries. Can be undone by calling it again. write clientXX/igmp.kill WARNING! This will of course not work if you are using a Reference client (has no kill implementation)

Nice to know

• All the variables that can be changed are found in defaults.hh.
• Since our packets were encapped outside of the IGMPRouter, and click doens't natively support to add info to the IP header, we needed to come up with our own solution without completely rewriting the flow. We cannot override Click classes, so we've imported the code of the element IPEncap and modified it to add the Router Alert option. (and recalculation of checksum). We've therefore renamed it to IPEncapDeluxe.
• The UDP data and IGMP messages use the same output, but the UDP data doesn't need an extra header. To split the flow of these packets, they will be colored using color 1 or 0, and PaintSwitch will distribute them accordingly.