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A Table Type Pattern (TTP) is an Open Network Foundation (ONF) effort to more easily enable an OpenFlow controller and switch to agree on a set of functionalities during configuration. A TTP describes specific forwarding behaviors that an OpenFlow controller can program using the OpenFlow-Switch protocol.

With respect to the Pica8 PICOS network operating system and white box switches, TTPs help overcome the limitations of Ternary Content Addressable Memory (TCAM) devices. TCAMs are power hungry, expensive memory devices that bloat the cost of solutions and cannot scale well. TTPs enable OpenFlow access to other ASIC tables, such as the VLAN, MAC, and IP along with TCAM tables. As the NOS opens up the different tables in the ASIC, an OpenFlow application is able to control the population of these tables directly in a normalized way. What this means is that the TTP is persistent across ASIC architectures. As a result, the SDN application can scale across ASIC architectures without any modification. For example, a fixed pipeline for IP routing, policy routing or an MPLS flow could be made consistent across any ASIC implementation.

This document details how to use TTP with the RYU OpenFlow Controller.


RYU Controller Configuration

RYU controller comes with sample applications that enable user to jumpstart SDN deployment. These sample applications are stored in the following directory:

Among all the applications, "ofctl_rest.py" (highlighted above) enables openflow REST interface for an open flow capable switch. This program supports OpenFlow versions 1.0 through 1.5. This provides a good framework to develop the APIs for configuring open flow rules.

pica8@ubuntu:~$ pip install ryu
pica8@ubuntu:~$ cd ryu
pica8@ubuntu:~/ryu$ ryu-manager ryu.app.ofctl_rest --verbose

loading app ryu.app.ofctl_rest
loading app ryu.controller.ofp_handler
instantiating app None of DPSet
creating context dpset
creating context wsgi
instantiating app ryu.app.ofctl_rest of RestStatsApi
instantiating app ryu.controller.ofp_handler of OFPHandler
(24694) wsgi starting up on http://0.0.0.0:8080
connected socket:<eventlet.greenio.base.GreenSocket object at 0x7fc8a6756950> address:('172.16.0.112', 39589)
hello ev <ryu.controller.ofp_event.EventOFPHello object at 0x7fc8a6623350>
move onto config mode
EVENT ofp_event->dpset EventOFPSwitchFeatures
switch features ev version=0x5,msg_type=0x6,msg_len=0x20,xid=0xb0590b8d,OFPSwitchFeatures(auxiliary_id=0,capabilities=15,datapath_id=6790866252693771931,n_buffers=256,n_tables=254)
move onto main mode
EVENT ofp_event->dpset EventOFPStateChange
DPSET: register datapath <ryu.controller.controller.Datapath object at 0x7fc8a668ca10>


Another important tool required to work with APIs is one of the following:

  1. POSTman : (https://www.getpostman.com)
  2. Swagger : (http://swagger.io/swagger-ui/)

The following example will demonstrate the use of POSTman to configure the open flow rules. Typically, these tools are used with a single switch to determine the REST APIs required to configure the switch. POSTman has a facility to run the set of APIs in an iterative process to perform the task multiple times if required.

The following is the configuration on the switch required to configure TTP:

admin@PicOS-OVS$ovs-vsctl show-running-config

Open_vSwitch ab7af11d-fc7a-4e9c-8165-36e67f92d043
  Bridge "br0"
    Controller fb5f8fd6-aca8-49f9-add0-800cd6c4d840
      is_connected: true
      role: other
      status: {current_version="OpenFlow14", sec_since_connect="691372", state=ACTIVE}
      target: "tcp:172.16.0.123:6633"
    datapath_id: "5e3e00e09500169a"
    datapath_type: "pica8"
    Port "te-1/1/1"
      Interface "te-1/1/1"
        type: "pica8"
      tag: 1
      vlan_mode: trunk
    Port "br0"
      Interface "br0"
        mtu: 1500
        type: internal
    Port "te-1/1/2"
      Interface "te-1/1/2"
        type: "pica8"
      tag: 1
      vlan_mode: trunk
    protocols: ["OpenFlow14"]

  Pica8 6d736702-1adb-44f8-93e6-998166ca813f
    hardware_type: "5401"
    pica_ttp_enable: true
    pica_ttp_name: RouterTTP.json



Step 1Setting the following environment variables in Postman helps in managing the variables


Table Type Patterns (TTP) are described in detail in the following blog (http://www.pica8.com/pica8-deep-dive/scaling-up-sdns-using-ttps-table-type-patterns/). The following is based on steps mentioned in the blog.


Step 2Creating a mac entry in the L2 table


Verify the switch has the flow configured

admin@PicOS-OVS$ovs-ofctl dump-flows br0

OFPST_FLOW reply (OF1.4) (xid=0x2):
 flow_id=3735291, cookie=0x0, duration=690201.683s, table=20, n_packets=n/a, n_bytes=n/a, dl_vlan=200,dl_dst=00:11:11:11:11:11 actions=goto_table:30


Step 3Creating a group entry (group_id = 1) for the egress L2 interface



Verify the group exists on the switch

admin@PicOS-OVS$ovs-ofctl dump-groups br0

OFPST_GROUP_DESC reply (OF1.4) (xid=0x2):
 group_id=1,type=indirect,bucket=weight:0,actions=output:97



Step 4Create a group entry (group_id = 2) for the egress L3 interface



Verify the switch has the configuration

admin@PicOS-OVS$ovs-ofctl dump-groups br0

OFPST_GROUP_DESC reply (OF1.4) (xid=0x2):
 group_id=1,type=indirect,bucket=weight:0,actions=output:97
 group_id=2,type=indirect,bucket=weight:0,actions=set_field:00:01:01:01:01:01->eth_src,set_field:00:02:02:02:01:01->eth_dst,set_field:2016->vlan_vid,group:1


Step 5Create a IP flow in the L3 table 



Verify the configuration on the switch

admin@PicOS-OVS$ovs-ofctl dump-flows br0

OFPST_FLOW reply (OF1.4) (xid=0x2):
 flow_id=3735291, cookie=0x0, duration=690201.683s, table=20, n_packets=n/a, n_bytes=n/a, dl_vlan=200,dl_dst=00:11:11:11:11:11 actions=goto_table:30
 flow_id=3735292, cookie=0x0, duration=690201.538s, table=30, n_packets=n/a, n_bytes=n/a, ip,nw_dst=10.0.1.0/24 actions=write_actions(group:2,dec_ttl),goto_table:60


"ovs-ofctl dump-flows br0" shows the software flow table configured by the controller. "ovs-appctl pica/dump-flows" shows the ASIC tables.

admin@PicOS-OVS$ovs-appctl pica/dump-flows

Ingress Port Table: (Total 0 flows)

VLAN Table: (Total 0 flows)

Termination MAC Table: (Total 1 flows)
 ID=5 dl_vlan=200,dl_dst=00:11:11:11:11:11, actions:goto(Unicast Routing Table)

Unicast Routing Table: (Total 1 flows)
 ID=6 ip,nw_dst=10.0.1.0/24, actions:group(id=2,indirect,n=1,b0(set(dl_src=00:01:01:01:01:01,dl_dst=00:02:02:02:01:01),set(vlan_vid=2016),group(id=1,indirect,n=1,b0(output:97)))),goto(Policy ACL Table)

Policy ACL Table: (Total 1 flows)
 ID=1 priority=18000009,tcp,dl_dst=00:e0:95:00:16:9a,nw_src=172.16.0.123,tp_src=6633, actions:set(queue=7),output:60000




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