Final edits (#165)

* Final instructions tidying

* Instructions

* Add final slides
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@ -16,13 +16,16 @@ you get started with P4 programming, organized into several modules:
* [Explicit Congestion Notification](./exercises/ecn) * [Explicit Congestion Notification](./exercises/ecn)
* [Multi-Hop Route Inspection](./exercises/mri) * [Multi-Hop Route Inspection](./exercises/mri)
4. Advanced Data Structures 4. Advanced Behavior
* [Source Routing](./exercises/source_routing) * [Source Routing](./exercises/source_routing)
* [Calculator](./exercises/calc) * [Calculator](./exercises/calc)
5. Dynamic Behavior
* [Load Balancing](./exercises/load_balance) * [Load Balancing](./exercises/load_balance)
## Presentation
The slides are available [online](http://bit.ly/p4d2-2018-spring) and
in the P4_tutorial.pdf in the tutorial directory.
## Obtaining required software ## Obtaining required software
If you are starting this tutorial at the Spring 2018 P4 Developer Day, If you are starting this tutorial at the Spring 2018 P4 Developer Day,

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@ -165,7 +165,7 @@ There are several ways that problems might manifest:
error emitted from the compiler and stop. error emitted from the compiler and stop.
2. `ecn.p4` compiles but does not support the control plane rules in 2. `ecn.p4` compiles but does not support the control plane rules in
the `sX-runtime.json` files that `make` tries to install using the `sX-runtime.json` files that `make` tries to install using
the BMv2 CLI. In this case, `make` will log the CLI tool output a Python controller. In this case, `make` will log the controller output
in the `logs` directory. Use these error messages to fix your `ecn.p4` in the `logs` directory. Use these error messages to fix your `ecn.p4`
implementation. implementation.
3. `ecn.p4` compiles, and the control plane rules are installed, but 3. `ecn.p4` compiles, and the control plane rules are installed, but

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@ -4,10 +4,10 @@ In this exercise, you will implement a form of load balancing based on
a simple version of Equal-Cost Multipath Forwarding. The switch you a simple version of Equal-Cost Multipath Forwarding. The switch you
will implement will use two tables to forward packets to one of two will implement will use two tables to forward packets to one of two
destination hosts at random. The first table will use a hash function destination hosts at random. The first table will use a hash function
(applied to a 5-tuple consisting of the source and destination (applied to a 5-tuple consisting of the source and destination IP
IP addresses, IP protocol, and source and destination TCP ports) addresses, IP protocol, and source and destination TCP ports) to
to select one of two hosts. The second table will use the select one of two hosts. The second table will use the computed hash
computed hash value to forward the packet to the selected host. value to forward the packet to the selected host.
> **Spoiler alert:** There is a reference solution in the `solution` > **Spoiler alert:** There is a reference solution in the `solution`
> sub-directory. Feel free to compare your implementation to the > sub-directory. Feel free to compare your implementation to the
@ -63,16 +63,9 @@ control plane. When a rule matches a packet, its action is invoked
with parameters supplied by the control plane as part of the rule. with parameters supplied by the control plane as part of the rule.
In this exercise, the control plane logic has already been In this exercise, the control plane logic has already been
implemented. As part of bringing up the Mininet instance, the implemented. As part of bringing up the Mininet instance, the `make`
`make` script will install packet-processing rules in the tables of script will install packet-processing rules in the tables of each
each switch. These are defined in the `s1-commands.txt` file. switch. These are defined in the `sX-runtime.json` files.
**Important:** A P4 program also defines the interface between the
switch pipeline and control plane. The `s1-commands.txt` file contains
a list of commands for the BMv2 switch API. These commands refer to
specific tables, keys, and actions by name, and any changes in the P4
program that add or rename tables, keys, or actions will need to be
reflected in these command files.
## Step 2: Implement Load Balancing ## Step 2: Implement Load Balancing
@ -105,9 +98,6 @@ Follow the instructions from Step 1. This time, your message from
`h1` should be delivered to `h2` or `h3`. If you send several `h1` should be delivered to `h2` or `h3`. If you send several
messages, some should be received by each server. messages, some should be received by each server.
### Food for thought
### Troubleshooting ### Troubleshooting
There are several ways that problems might manifest: There are several ways that problems might manifest:
@ -116,10 +106,10 @@ There are several ways that problems might manifest:
report the error emitted from the compiler and stop. report the error emitted from the compiler and stop.
2. `load_balance.p4` compiles but does not support the control plane 2. `load_balance.p4` compiles but does not support the control plane
rules in the `sX-commands.txt` files that `make` tries to install rules in the `sX-runtime.json` files that `make` tries to install
using the BMv2 CLI. In this case, `make` will log the CLI tool output using the Python controller. In this case, `make` will log the
in the `logs` directory. Use these error messages to fix your `load_balance.p4` controller output in the `logs` directory. Use the error messages to
implementation. fix your `load_balance.p4` implementation.
3. `load_balance.p4` compiles, and the control plane rules are 3. `load_balance.p4` compiles, and the control plane rules are
installed, but the switch does not process packets in the desired way. installed, but the switch does not process packets in the desired way.
@ -139,4 +129,4 @@ mn -c
## Next Steps ## Next Steps
Congratulations, your implementation works! Congratulations, your implementation works and you have finished the tutorial!

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@ -211,18 +211,22 @@ There are several ways that problems might manifest:
1. `mri.p4` fails to compile. In this case, `make` will report the 1. `mri.p4` fails to compile. In this case, `make` will report the
error emitted from the compiler and stop. error emitted from the compiler and stop.
2. `mri.p4` compiles but does not support the control plane rules in 2. `mri.p4` compiles but does not support the control plane rules in
the `sX-runtime.json` files that `make` tries to install using the BMv2 CLI. the `sX-runtime.json` files that `make` tries to install using a
In this case, `make` will log the CLI tool output in the `logs` directory. Python controller. In this case, `make` will log the controller
Use these error messages to fix your `mri.p4` implementation. output in the `logs` directory. Use these error messages to fix
your `mri.p4` implementation.
3. `mri.p4` compiles, and the control plane rules are installed, but 3. `mri.p4` compiles, and the control plane rules are installed, but
the switch does not process packets in the desired way. The the switch does not process packets in the desired way. The
`/tmp/p4s.<switch-name>.log` files contain trace messages describing `/tmp/p4s.<switch-name>.log` files contain trace messages
how each switch processes each packet. The output is detailed and can describing how each switch processes each packet. The output is
help pinpoint logic errors in your implementation. The detailed and can help pinpoint logic errors in your implementation.
`build/<switch-name>-<interface-name>.pcap` also contains the pcap of The `build/<switch-name>-<interface-name>.pcap` also contains the
packets on each interface. Use `tcpdump -r <filename> -xxx` to print pcap of packets on each interface. Use `tcpdump -r <filename> -xxx`
the hexdump of the packets. to print the hexdump of the packets.
4. `mri.p4` compiles and all rules are installed. Packets go through 4. `mri.p4` compiles and all rules are installed. Packets go through
and the logs show that the queue length is always 0. Then either and the logs show that the queue length is always 0. Then either
reduce the link bandwidth in `topology.json`. reduce the link bandwidth in `topology.json`.
@ -241,4 +245,3 @@ make stop
Congratulations, your implementation works! Move on to [Source Congratulations, your implementation works! Move on to [Source
Routing](../source_routing). Routing](../source_routing).

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@ -13,8 +13,8 @@ to the specified port number.
Your switch must parse the source routing stack. Each item has a bos Your switch must parse the source routing stack. Each item has a bos
(bottom of stack) bit and a port number. The bos bit is 1 only for the (bottom of stack) bit and a port number. The bos bit is 1 only for the
last entry of stack. Then at ingress, it should pop an entry from the last entry of stack. Then at ingress, it should pop an entry from the
stack and set the egress port accordingly. Note that the last hop can stack and set the egress port accordingly. The last hop may also
also revert back the etherType to `TYPE_IPV4`. revert back the etherType to `TYPE_IPV4`.
> **Spoiler alert:** There is a reference solution in the `solution` > **Spoiler alert:** There is a reference solution in the `solution`
> sub-directory. Feel free to compare your implementation to the > sub-directory. Feel free to compare your implementation to the