Changes between Initial Version and Version 1 of GEC15Agenda/AdvancedGENITopoOmni/Instructions/ClickExampleExperiment

10/18/12 22:14:26 (7 years ago)



  • GEC15Agenda/AdvancedGENITopoOmni/Instructions/ClickExampleExperiment

    v1 v1  
     3= Example Experiment - Click Routers =
     5In this example experiment, you will configure and run a non-IP software routing configuration, using the [ Click] modular router and [ ProtoGENI] hosts. In this example, we'll be running click in user mode. Once you have the prerequisites in place, you should be able to complete this example experiment in under an hour.
     7Please note that you can't just cut and paste all of the commands. There are additional instructions in the text.
     9== Prerequisites ==
     11Before beginning this experiment, you should:
     13 * Have a GENI credential. If you don't, check out SignMeUp.
     14 * Configure omni (version 1.5.2 or later) on your machine. Be sufficiently comfortable with omni to verify that a '''listresources''' command works and to know when your slice is ready using '''sliverstatus'''.
     16Information on obtaining GENI credentials and omni is available at SignMeUp and [wiki:HowToUseOmni] or by contacting [].
     18== Setup ==
     20Create a new directory, '''click-example''', on your machine. You will do the rest of your work from this directory.
     23mkdir click-example
     24cd click-example
     27Download [attachment:click-example.rspec?format=raw the attached rspec file] and save it in your '''click-example''' directory, using the name '''click-example.rspec'''. Be sure to use raw mode.
     29If you haven't already, add your omni source and examples directories to your PATH:
     32export PATH=$PATH:/path/to/gcf-1.x.x/src:/path/to/gcf-1.x.x/examples
     35If you haven't already, add your omni source directory to your PYTHONPATH:
     38export PYTHONPATH=$PYTHONPATH:/path/to/gcf-1.x.x/src
     41(Optional) You'll be making heavy use of your private key to log into your ProtoGENI hosts in the steps below. If your key is encrypted, you might want to take a look at ways for [wiki:HowTo/LoginToNodes#ManagingSSHKeys managing your ssh keys] to make this easier.
     43== Obtain your resources ==
     45Create your slice. Please don't use my stupid slice name.  This example will use the Utah ProtoGENI site. You can choose a different site by selecting a different aggregate manager with the -a switch.
     47{{{ createslice -a StupidSliceName
     51Create a sliver and add resources. (You changed the slice name, right?)
     53{{{ createsliver -a StupidSliceName click-example.rspec
     57Wait until your sliver is ready, typically a few minutes. (You can monitor your sliver with [ Flack] or use omni's '''sliverstatus''' command as shown below.)
     59{{{ sliverstatus -a StupidSliceName
     63When your sliver is ready, run the '''readyToLogin''' script to get login information for your nodes. Use the same aggregate manager and slice name that you used for your '''sliverstatus''' command above.
     64{{{ -a StupidSliceName
     68You'll get a big chunk of information, but you're interested in the '''ssh''' command information near the end.
     71... <lots of output> ...
     73Aggregate [] has a ProtoGENI sliver.
     75's geni_status is: ready
     77Login using:
     78        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     79's geni_status is: ready
     81Login using:
     82        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     83's geni_status is: ready
     85Login using:
     86        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     87's geni_status is: ready
     89Login using:
     90        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     91's geni_status is: ready
     93Login using:
     94        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     95's geni_status is: ready
     97Login using:
     98        xterm -e ssh -i /Users/mberman/.ssh/id_rsa &
     103The six lines that start with '''xterm -e ssh ...''' contain the information you need to connect to your nodes. There are six nodes in this experiment, and you will want to open a window for each. Copy and paste the commands, '''adding the -A switch to each ssh command''' as shown below. You will get six new terminal windows, one on each node of your experiment. (You should say yes if you are prompted to accept the RSA key of the remote host.)
     106xterm -e ssh -A -i /Users/mberman/.ssh/id_rsa &
     109The shell prompt in each of your new terminal windows will tell you the host name. The four routers in your experiment are named '''top''', '''left''', '''right''', and '''bottom'''. The two end hosts are named '''hosta''' and '''hostb'''. You may want to rearrange the windows on your screen, putting the router hosts in the locations indicated, with the end hosts off to the side.
     111'''Tip''': If you want to login to your hosts from a different host than the one you are running Omni on, take a look [wiki:HowTo/LoginToNodes here] for some tips about how to do this.
     113== Configure your routers ==
     115''In each of your four router hosts,'' run the extractClickConfig script as shown below.
     118[mberman@top ~]$ /local/click-example/
     121You'll get output something like this:
     123Your host information:
     124        hostA:
     125        top:
     126        left:
     127        right:
     128        bottom:
     129        hostB:
     133(If you are prompted for a password, check to make sure that you provided the -A switch in your xterm command above.)
     135The extractClickConfig script produces router configurations for your experiment. It also creates a diagram of your experiment. Copy it back to the '''click-example''' directory on your local host so you can view it. There's a copy on each of your router hosts. I've chosen, which is the top router, but it doesn't matter. You'll need to find the host name in the script output above, and then run this command ''on your local machine''.
     138scp .
     141Once you have '''myslice.png''' on your local machine, open it in a browser or other viewer program. Your slice will look something like the one below (see [attachment:myslice.png]). The overall configuration should be the same, with two end hosts, named hostA and hostB, and four routers (top, left, right, bottom) in a diamond configuration. The host names, interface names, and MAC addresses will be different, depending on the actual resources assigned to your slice.
     143[[Image(myslice.png, 25%)]]
     145The four routers interconnected by solid lines are your "core network," which will run a non-standard, non-IP protocol. The dashed lines out to the end hosts carry standard IP traffic.
     147== Turn off internet protocol ==
     149At this point, your network is still running IP. You can check by running a ping. In your '''hosta''' terminal window, run this command.
     152ping -c 3 hostb
     155The command should succeed, with output like this:
     158PING hostB-link-B ( 56(84) bytes of data.
     15964 bytes from hostB-link-B ( icmp_seq=1 ttl=61 time=1.38 ms
     16064 bytes from hostB-link-B ( icmp_seq=2 ttl=61 time=1.19 ms
     16164 bytes from hostB-link-B ( icmp_seq=3 ttl=61 time=1.53 ms
     163--- hostB-link-B ping statistics ---
     1643 packets transmitted, 3 received, 0% packet loss, time 2004ms
     165rtt min/avg/max/mdev = 1.193/1.370/1.531/0.138 ms
     168Since our experiment doesn't want IP, let's turn it off. ''On each of your four router hosts,'' run this command:
     171sh ./
     174You'll get output like this (the interface names may be different):
     177Disabling IP on interface eth2
     178Disabling IP on interface eth4
     181To verify that IP is really off, try another ping. On '''hosta''':
     183ping -c 3 hostb
     186The command should take twelve seconds to time out, then fail with output like this:
     189PING hostB-link-B ( 56(84) bytes of data.
     191--- hostB-link-B ping statistics ---
     1923 packets transmitted, 0 received, 100% packet loss, time 11999ms
     195== Start your routers ==
     197The extractor script produces a click configuration file for each of your routers.  ''On each of your four router hosts,'' run this command:
     200sh ./
     203You'll get output like this. (Don't worry about the warning messages, Click is just reminding you that you have no IP addresses in your core network.) The shell prompt won't come back, but you'll see the debugging output of the Click router in the terminal window.
     206Stopping any running Click routers
     207Starting Click router While initializing ‘FromDevice@18 :: FromDevice’:
     209  warning: eth2: no IPv4 address assigned While initializing ‘FromDevice@21 :: FromDevice’:
     211  warning: eth4: no IPv4 address assigned
     214Congratulations! You are now running a non-IP core network on your four routers, along with a (primitive) non-IP multipath routing algorithm. You're ready to experiment with this configuration.
     216== Send some traffic ==
     218Now you'll use your two edge hosts, '''hostA''' and '''hostB''' to send traffic along your network.  Since these end hosts are not running your modified protocol, they'll rely on the '''top''' and '''bottom''' routers to transform their IP packets into your modified protocol on entry to the core network and back into IP packets on exit.
     220In your terminal window on '''hostB''', instruct '''nc''' to listen for a UDP connection on port 24565 (or some other port that catches your fancy).
     222[mberman@hostb ~]$ nc -ul 24565
     225Then connect to it from your terminal window on '''hostA''':
     227[mberman@hosta ~]$ nc -u hostb 24565
     230You've established a simple text chat connection. Enter a line of text in either window, and it should appear in the other. Of course to do this, the text is travelling through your core network, using your non-standard protocol and routing. So type a message into each window, and make sure it appears in the other.
     232That's it!  Now, let's look inside to see what's going on.
     234== Looking under the hood ==
     236Please note: the interface names and MAC addresses below are for the sample configuration shown in the figure above. You will want to refer to your network diagram to get the correct interfaces and addresses for your configuration.
     238Let's take a look at what's happening in the four routers in your configuration. There are two basic router configurations. (You can find all of these files on any of your router hosts.)
     240=== Packet transformation ===
     242The more interesting configuration appears here, in the '''''' configuration file.
     245// This portion accepts IP packets,
     246// reformats them, and routes them
     247// to an internal router.
     248route :: Classifier(27/01%01,-);
     250modify :: Unstrip(2) ->
     251    StoreData(0, "AliceWasHere3546") ->
     252    route;
     254FromDevice(eth3, PROMISC true) ->
     255    Classifier(12/0800) ->
     256    modify;
     258route[0] -> left :: EtherEncap(0x7744, 00:04:23:b7:14:76, 00:04:23:b7:18:fa) ->
     259    SimpleQueue ->
     260    Print(outL) ->
     261    ToDevice(eth2);
     263route[1] -> right :: EtherEncap(0x7744, 00:04:23:b7:1c:e0, 00:04:23:b7:19:2e) ->
     264    SimpleQueue ->
     265    Print(outR) ->
     266    ToDevice(eth4);
     268// This portion accepts non-IP packets
     269// with an ether type of 0x7744
     270// from an internal router, restores
     271// them to IP format, and forwards.
     272restore :: SimpleQueue ->
     273    Strip(30) ->
     274    EtherEncap(0x800, 00:04:23:b7:14:77, 00:04:23:b7:20:00) ->
     275    ToDevice(eth3);
     277FromDevice(eth2) -> Classifier(12/7744) -> Print(inL) -> restore;
     278FromDevice(eth4) ->  Classifier(12/7744) -> Print(inR) -> restore;
     281As indicated in the comments, the top portion of the configuration listens ('''!FromDevice''') for IP packets arriving on the interface connected to '''hostA''' (that's '''eth3''' in this example). It then creates a new 16-byte field at the head of the packet (two bytes added by the '''Unstrip''' operation, plus the existing 14-byte Ethernet header. It fills that field with what could be important routing instructions, but in this case is just graffiti ('''!StoreData'''). The '''route''' operation then routes the packet via either the '''left''' or '''right''' router toward '''hostB'''. In either case, it wraps the packet in a fresh Ethernet header ('''!EtherEncap''') with a distinctive ether type code (0x7744), logs the new packet on its way out ('''Print''') and sends it out on the correct interface ('''!ToDevice''').
     283The bottom portion of the configuration is intended for packets coming out of the core network to '''hostA'''.  It accepts packets from either the '''left''' or '''right''' router, logs them, strips off thirty bytes (Ethernet header plus your 16-byte new header field), puts on a fresh Ethernet header, and sends them along to '''hostA'''.
     285The configuration for the '''bottom''' router is exactly symmetric, routing packets between '''hostB''' and the core network, but using different graffiti.
     287=== Simple Forwarding ===
     289The '''left''' router configuration is much simpler.  Here's the '''''' file:
     292// Copy packets from top to bottom.
     293FromDevice(eth2) ->
     294    StoreEtherAddress(00:04:23:b7:42:b6, dst) ->
     295    StoreEtherAddress(00:04:23:b7:18:fb, src) ->
     296    SimpleQueue ->
     297    Print(top) ->
     298    ToDevice(eth3);
     299// Copy packets from bottom to top.
     300FromDevice(eth3) ->
     301    StoreEtherAddress(00:04:23:b7:14:76, dst) ->
     302    StoreEtherAddress(00:04:23:b7:18:fa, src) ->
     303    SimpleQueue ->
     304    Print(bottom) ->
     305    ToDevice(eth2);
     308This configuration just blindly forwards packets. It picks up any packet from the '''top''' router, updates the Ethernet header, and passes it along to the '''bottom''' router. The same applies in the reverse direction.  Again, the configuration for the '''right''' router is exactly analogous.
     310=== Monitoring your core network ===
     312Let's watch how the packets travel through the network. The terminal windows on your four router hosts show the log output from the '''Print''' statements shown above, one line per packet.
     314Type <enter> a few times in each router window to create a space below the existing log entries, so you can identify new log messages as they appear.
     316Now go to your window for hostA, where your '''nc''' command is still running. Type a message into this window. You should see a log message in three of your four router windows. In this example, you might see:
     318In the '''top''' router log:
     320outR:   76 | 000423b7 192e0004 23b71ce0 7744416c 69636557 61734865
     323This log entry says that the '''top''' router received a packet from '''hostA''', modified it, and sent it out to the '''right''' router. If the entry started with '''outL''', that would indicate that it sent the packet out to the '''left''' router. Let's look a bit at the start of the packet (the first 24 bytes are logged). It starts with an Ethernet header. The first six bytes are the MAC address of the destination interface, that's 00:04:23:B7:19:2E, the MAC address of '''eth4''' on '''right'''. The next six bytes are the MAC address of the source interface, 00:04:23:B7:1C:E0, or '''eth4''' on '''top'''. Next comes your ether type, 0x7744. The remaining bytes, "416c 69636557 61734865" are the start of the first field in your new protocol, "!AliceWasHe" in ASCII.
     325Since this packet was routed to the right, there's an entry in the '''right''' router log. This entry indicates that a packet was received from '''top'''. The logged contents show the packet sent to '''bottom''', with rewritten MAC addresses, corresponding to '''eth5''' on '''bottom''' and '''eth5''' on '''right'''.
     328top:   76 | 000423b7 42590004 23b7192f 7744416c 69636557 61734865
     331Finally, here's the entry on '''bottom''':
     333inR:   76 | 000423b7 42590004 23b7192f 7744416c 69636557 61734865
     336It shows the same packet received from '''right'''. After logging, the packet is rewritten into IP and sent to '''hostB'''.
     338Try typing a few different lines to hostA. You should see some packets routed to the left and some to the right. The routing decision is based on the '''route :: Classifier(27/01%01,-);''' entry in the '''top''' router configuration. Here, the router is looking at the low-order bit of the checksum on the initial IP packet (now at byte position 27 with the addition of the new sixteen byte field at the start of the header). Packets with odd checksums go to the left; those with even checksums go right.
     340Try typing a few lines to hostB. You should see similar behavior, but starting from '''bottom''' and working up. You'll also see the different value inserted in the new header field.
     342== Clean up ==
     344When you're done, please release your resources so they'll be available to others.
     346{{{ deletesliver -a StupidSliceName
     350== Moving forward with your experiment ==
     352This sample experiment is just a very simple demonstration of how to run a Click-based routing configuration using ProtoGENI. For a more meaningful experiment, you may want to try some of the variations described below. We'd love to hear what you're doing with Click and GENI, and we're here to help. Please let us know at [].
     354=== Improved routing ===
     356Instead of writing "!AliceWasHere" in your packets, perhaps include some real routing instructions. Modify the Click configurations to route packets accordingly.
     358=== Richer topology ===
     360Incorporate additional hosts into a core network topology that's more interesting than a simple diamond.
     362=== Improved performance with kernel-level Click ===
     364The Click router supports kernel-level operation. The principles are the same, but the setup is a bit more involved. To use kernel-level Click, you will probably want first to develop and debug your setup at the user level. Drop us a line at [] for help setting up Click in kernel mode.
     366=== Wide-area routing ===
     368Modify your rspec to include some ProtoGENI hosts on the Internet2 backbone or at multiple ProtoGENI sites. Additional information available at or [].