Cleanup and minor edits

EXERCISE-3.md

@@ -121,7 +121,7 @@ ONOS app that includes a pipeconf. The pipeconf-related files are the following:
 * [PipelinerImpl.java][PipelinerImpl.java]: An implementation of the `Pipeliner`
   driver behavior;
 
-To build the ONOS app (including the pipeconf), In the second terminal window,
+To build the ONOS app (including the pipeconf), in the second terminal window,
 use the command:
 
 ```
@@ -164,8 +164,7 @@ information such as:
 * The ONOS driver to use for each device, `stratum-bmv2` in this case;
 * The pipeconf to use for each device, `org.onosproject.ngsdn-tutorial` in this
   case, as defined in [PipeconfLoader.java][PipeconfLoader.java];
-* Configuration specific to our custom app, such as the `myStationMac` or a flag
-  to signal if a switch has to be considered a spine or not.
+* Configuration specific to our custom app (`fabricDeviceConfig`)
 
 This file contains also information related to the IPv6 configuration associated
 to each switch interface. We will discuss this information in more details in
@@ -180,8 +179,6 @@ $ make netcfg
 This command will push the `netcfg.json` to ONOS, triggering discovery and
 configuration of the 4 switches.
 
-FIXME: do log later, or deactivate lldp app for now to avoid clogging with error messages
-
 Check the ONOS log (`make onos-log`), you should see messages like:
 
 ```
@@ -222,8 +219,8 @@ id=device:spine1, available=true, role=MASTER, type=SWITCH, driver=stratum-bmv2:
 id=device:spine2, available=true, role=MASTER, type=SWITCH, driver=stratum-bmv2:org.onosproject.ngsdn-tutorial
 ```
 
-Make sure you see `available=true` for all devices. That means ONOS is connected
-to the device and the pipeline configuration has been pushed.
+Make sure you see `available=true` for all devices. That means ONOS has a gRPC
+channel open to the device and the pipeline configuration has been pushed.
 
 
 #### Ports
@@ -292,10 +289,10 @@ deviceId=device:leaf1, groupCount=1
 "Group" is an ONOS northbound abstraction that is mapped internally to different
 types of P4Runtime entities. In this case you should see 1 group of type `CLONE`.
 
-`CLONE` groups are mapped to a P4Runtime `CloneSessionEntry`, here used to clone
-packets to the controller via packet-in. Note that the `id=0x63` is the same as
-`#define CPU_CLONE_SESSION_ID 99` in the P4 program. This ID is hardcoded in the
-pipeconf code, as the group is created by
+`CLONE` groups are mapped to P4Runtime `CloneSessionEntry` entities, here used
+to clone packets to the controller via packet-in. Note that the `id=0x63` is the
+same as `#define CPU_CLONE_SESSION_ID 99` in the P4 program. This ID is
+hardcoded in the pipeconf code. The group is created by
 [PipelinerImpl.java][PipelinerImpl.java] in response to flow objectives mapped
 to the ACL table and requesting to clone packets such as NDP and ARP.
 

EXERCISE-4.md

@@ -1,11 +1,12 @@
 # Exercise 4: Enabling link discovery via P4Runtime packet I/O
 
-In this exercise, you will be asked to integrate the ONOS built-in link discovery
-service with your P4 program. ONOS performs link discovery by using controller
-packet-in/out. To make this work, you will need to apply simple changes to the
-starter P4 code, validate the P4 changes using PTF-based data plane unit tests,
-and finally, apply changes to the pipeconf Java implementation to enable ONOS's
-built-in apps use the packet-in/out support provided by your P4 implementation.
+In this exercise, you will be asked to integrate the ONOS built-in link
+discovery service with your P4 program. ONOS performs link discovery by using
+controller packet-in/out. To make this work, you will need to apply simple
+changes to the starter P4 code, validate the P4 changes using PTF-based data
+plane unit tests, and finally, apply changes to the pipeconf Java implementation
+to enable ONOS's built-in apps to use the packet-in/out support provided by your
+P4 implementation.
 
 ## Controller packet I/O with P4Runtime
 
@@ -50,13 +51,11 @@ The P4 starter code already provides support for the following capabilities:
 
 * Parse the `cpu_out` header (if the ingress port is the CPU one)
 * Emit the `cpu_in` header as the first one in the deparser
-* Skip ingress pipeline processing for packet-outs and set the egress port to
-  the one specified in the `cpu_out` header
 * Provide an ACL table with ternary match fields and an action to clone
   packets to the CPU port (used to generate a packet-ins)
 
-One piece is missing to provide complete packet-in support, and you have to modify
-the P4 program to implement it:
+Something is missing to provide complete packet-in/out support, and you have to
+modify the P4 program to implement it:
 
 1. Open `p4src/main.p4`;
 2. Look for the implementation of the egress pipeline (`control EgressPipeImpl`);
@@ -230,8 +229,8 @@ Link stats are derived by ONOS by periodically obtaining the port counters for
 each device. ONOS internally uses gNMI to read port information, including
 counters.
 
-In this case, you should see ~1 packet/s, as that's the rate of packet-outs
-generated by the `lldpprovider` app.
+In this case, you should see approx 1 packet/s, as that's the rate of
+packet-outs generated by the `lldpprovider` app.
 
 ## Congratulations!
 

EXERCISE-5.md

@@ -27,7 +27,7 @@ are used to provide interface configuration to ONOS.
 ### Our P4 implementation of L2 bridging
 
 The starter P4 code already defines tables to forward packets based on the
-Ethernet address, precisely, two distinct tables to handle two different types
+Ethernet address, precisely, two distinct tables, to handle two different types
 of L2 entries:
 
 1. Unicast entries: which will be filled in by the control plane when the
@@ -36,30 +36,29 @@ of L2 entries:
    (NS) messages to all host-facing ports;
 
 For (2), unlike ARP messages in IPv4, which are broadcasted to Ethernet
-destination address FF:FF:FF:FF:FF:FF, NDP messages are sent to special
-Ethernet addresses specified by RFC2464. These addresses are prefixed
-with 33:33 and the last four octets are the last four octets of the IPv6
-destination multicast address. The most straightforward way of matching
-on such IPv6 broadcast/multicast packets, without digging in the details
-of RFC2464, is to use a ternary match on `33:33:**:**:**:**`, where `*` means
-"don't care".
+destination address FF:FF:FF:FF:FF:FF, NDP messages are sent to special Ethernet
+addresses specified by RFC2464. These addresses are prefixed with 33:33 and the
+last four octets are the last four octets of the IPv6 destination multicast
+address. The most straightforward way of matching on such IPv6
+broadcast/multicast packets, without digging in the details of RFC2464, is to
+use a ternary match on `33:33:**:**:**:**`, where `*` means "don't care".
 
 For this reason, our solution defines two tables. One that matches in an exact
 fashion `l2_exact_table` (easier to scale on switch ASIC memory) and one that
 uses ternary matching `l2_ternary_table` (which requires more expensive TCAM
 memories, usually much smaller).
 
 These tables are applied to packets in an order defined in the `apply` block
-area of the ingress pipeline (`IngressPipeImpl`):
+of the ingress pipeline (`IngressPipeImpl`):
 
 ```
 if (!l2_exact_table.apply().hit) {
     l2_ternary_table.apply();
 }
 ```
 
-The ternary table has lower priority and is applied only if a matching entry is
-not found in the exact one.
+The ternary table has lower priority and it's applied only if a matching entry
+is not found in the exact one.
 
 **Note**: To keep things simple, we won't be using VLANs to segment our L2
 domains. As such, when matching packets in the `l2_ternary_table`, these will be

EXERCISE-6.md

@@ -90,7 +90,7 @@ The first step will be to add new tables to `main.p4`.
 We already provide ways to handle NDP NS and NA exchanged by hosts connected to
 the same subnet (see `l2_ternary_table`). However, for hosts, the Linux
 networking stack takes care of generating a NDP NA reply. For the switches in
-our fabric, there's no Linux networking stack associated to it.
+our fabric, there's no traditional networking stack associated to it.
 
 There are multiple solutions to this problem:
 
@@ -106,7 +106,7 @@ There are multiple solutions to this problem:
 option. You can decide to go with a different one, but you should keep in mind
 that there will be less starter code for you to re-use.
 
-The idea is simple, NDP NA packets have the same header structure as NDP NS
+The idea is simple: NDP NA packets have the same header structure as NDP NS
 ones. They are both ICMPv6 packets with different header field values, such as
 different ICMPv6 type, different Ethernet addresses etc. A switch that knows the
 MAC address of a given IPv6 target address found in an NDP NS request, can
@@ -117,13 +117,13 @@ To implement P4-based generation of NDP NA messages, look in
 `ndp_ns_to_na` to transform an NDP NS packet into an NDP NA one. Your task is to
 implement a table that uses such action.
 
-This table should define a mapping between the interface IPv6 addresses
-provided in [netcfg.json](mininet/netcfg.json) and the `myStationMac` associated
-to each switch (also defined in netcfg.json). When an NDP
-NS packet is received, asking to resolve one of such IPv6 addresses, the
-`ndp_ns_to_na` action should be invoked with the given `myStationMac` as
-parameter. The ONOS app will be responsible of inserting entries in this table
-according to the content of netcfg.json.
+This table should define a mapping between the interface IPv6 addresses provided
+in [netcfg.json](mininet/netcfg.json) and the `myStationMac` associated to each
+switch (also defined in netcfg.json). When an NDP NS packet is received, asking
+to resolve one of such IPv6 addresses, the `ndp_ns_to_na` action should be
+invoked with the given `myStationMac` as parameter. The ONOS app will be
+responsible of inserting entries in this table according to the content of
+netcfg.json.
 
 The ONOS app already provides a component
 [NdpReplyComponent.java](app/src/main/java/org/p4/p4d2/tutorial/NdpReplyComponent.java)

app/src/main/java/org/onosproject/ngsdn/tutorial/L2BridgingComponent.java

@@ -180,7 +180,7 @@ private void insertMulticastGroup(DeviceId deviceId) {
         }
 
         log.info("Adding L2 multicast group with {} ports on {}...",
-                 ports.size(), deviceId);
+                ports.size(), deviceId);
 
         // Forge group object.
         final GroupDescription multicastGroup = Utils.buildMulticastGroup(
@@ -191,7 +191,7 @@ private void insertMulticastGroup(DeviceId deviceId) {
     }
 
     /**
-     * Insert flow rules matching matching ethernet destination
+     * Insert flow rules matching ethernet destination
      * broadcast/multicast addresses (e.g. ARP requests, NDP Neighbor
      * Solicitation, etc.). Such packets should be processed by the multicast
      * group created before.
@@ -313,7 +313,7 @@ private void insertUnmatchedBridgingFlowRule(DeviceId deviceId) {
     private void learnHost(Host host, DeviceId deviceId, PortNumber port) {
 
         log.info("Adding L2 unicast rule on {} for host {} (port {})...",
-                 deviceId, host.id(), port);
+                deviceId, host.id(), port);
 
         // *** TODO EXERCISE 5
         // Modify P4Runtime entity names to match content of P4Info file (look
@@ -324,7 +324,7 @@ private void learnHost(Host host, DeviceId deviceId, PortNumber port) {
         final MacAddress hostMac = host.mac();
         final PiCriterion hostMacCriterion = PiCriterion.builder()
                 .matchExact(PiMatchFieldId.of("MODIFY ME"),
-                            hostMac.toBytes())
+                        hostMac.toBytes())
                 .build();
 
         // Action: set output port
@@ -425,7 +425,7 @@ public void event(HostEvent event) {
 
             mainComponent.getExecutorService().execute(() -> {
                 log.info("{} event! host={}, deviceId={}, port={}",
-                         event.type(), host.id(), deviceId, port);
+                        event.type(), host.id(), deviceId, port);
 
                 learnHost(host, deviceId, port);
             });
@@ -500,7 +500,7 @@ private void setUpAllDevices() {
                 // For all hosts connected to this device...
                 hostService.getConnectedHosts(device.id()).forEach(
                         host -> learnHost(host, host.location().deviceId(),
-                                          host.location().port()));
+                                host.location().port()));
             }
         });
     }

solution/app/src/main/java/org/onosproject/ngsdn/tutorial/L2BridgingComponent.java

@@ -191,7 +191,7 @@ private void insertMulticastGroup(DeviceId deviceId) {
     }
 
     /**
-     * Insert flow rules matching matching ethernet destination
+     * Insert flow rules matching ethernet destination
      * broadcast/multicast addresses (e.g. ARP requests, NDP Neighbor
      * Solicitation, etc.). Such packets should be processed by the multicast
      * group created before.
@@ -273,10 +273,10 @@ private void insertUnmatchedBridgingFlowRule(DeviceId deviceId) {
         // Match unmatched traffic - Match ternary **:**:**:**:**:**
         final PiCriterion unmatchedTrafficCriterion = PiCriterion.builder()
                 .matchTernary(
-                    PiMatchFieldId.of("hdr.ethernet.dst_addr"),
-                    MacAddress.valueOf("00:00:00:00:00:00").toBytes(),
-                    MacAddress.valueOf("00:00:00:00:00:00").toBytes())
-            .build();
+                        PiMatchFieldId.of("hdr.ethernet.dst_addr"),
+                        MacAddress.valueOf("00:00:00:00:00:00").toBytes(),
+                        MacAddress.valueOf("00:00:00:00:00:00").toBytes())
+                .build();
 
         // Action: set multicast group id
         final PiAction setMcastGroupAction = PiAction.builder()