Hey there everyone, I am working on this simple routing application where it proactively finds the shortest and the longest paths from a source to a destination, and installs the flow entries on the switches in a path.
It uses networkx.shortest_simple_paths() to calculate the paths (this function calculates the paths and sort them from the shortest to the longest). In small network topologies the app works fine. In denser topologies (e.g. 3x3 torus topology) when I use shortest path to forward traffic it works. However, when I try to install the flow entries for the longest paths, nothing happens. Even though, the match and flow rules are created and sent to the switches. They are not being installed and no error is raised. When I use ovs-ofctl it shows that the flow tables are empty. I would appreciate it, if someone could tell me what are some of the possible causes of this behavior. The function that installs the flow entries is as follows (I took this code from this <https://github.com/muzixing/ryu/blob/master/ryu/app/network_awareness/shortest_forwarding.py> Ryu app, even in the original app I observe the same behavior). def install_flow(self, datapaths, link_to_port, access_table, path, flow_info, buffer_id, data=None): ''' Install flow entires for roundtrip: go and back. @parameter: path=[dpid1, dpid2...] flow_info=(eth_type, src_ip, dst_ip, in_port) ''' if path is None or len(path) == 0: self.logger.info("Path error!") return in_port = flow_info[3] first_dp = datapaths[path[0]] out_port = first_dp.ofproto.OFPP_LOCAL back_info = (flow_info[0], flow_info[2], flow_info[1]) self.logger.info("--------------[MAIN_APP][install_flow]\n" "datapath %s,\n in_port %s,\n L2P %s,\n access_table %s,\n path %s,\n flow_info %s\n, back_info %s" "------------------------------------------------------- ", datapaths, in_port, link_to_port, access_table, path, flow_info, back_info) # inter_link if len(path) > 2: for i in xrange(1, len(path) - 1): self.logger.info("[DEBUG][MAIN_APP][install_flow] path > 2 | i = %s, flow %s, path %s, sw %s", i, flow_info, path, path[i]) port = self.get_port_pair_from_link(link_to_port, path[i - 1], path[i]) port_next = self.get_port_pair_from_link(link_to_port, path[i], path[i + 1]) if port and port_next: src_port, dst_port = port[1], port_next[0] datapath = datapaths[path[i]] self.send_flow_mod(datapath, flow_info, src_port, dst_port) self.send_flow_mod(datapath, back_info, dst_port, src_port) self.logger.info("[DEBUG][MAIN_APP][install_flow] path > 2 |inter_link flow install") if len(path) > 1: # the last flow entry: tor -> host port_pair = self.get_port_pair_from_link(link_to_port, path[-2], path[-1]) self.logger.info("[DEBUG][MAIN_APP][install_flow] path > 1 | flow %s, path %s, link(%s, %s)=port(%s)", flow_info, path, path[-2], path[-1], port_pair) if port_pair is None: self.logger.info("Port is not found") return src_port = port_pair[1] dst_port = self.get_port(flow_info[2], access_table) if dst_port is None: self.logger.info("Last port is not found.") return last_dp = datapaths[path[-1]] self.send_flow_mod(last_dp, flow_info, src_port, dst_port) self.send_flow_mod(last_dp, back_info, dst_port, src_port) # the first flow entry port_pair = self.get_port_pair_from_link(link_to_port, path[0], path[1]) if port_pair is None: self.logger.info("Port not found in first hop.") return out_port = port_pair[0] self.send_flow_mod(first_dp, flow_info, in_port, out_port) self.send_flow_mod(first_dp, back_info, out_port, in_port) self.send_packet_out(first_dp, buffer_id, in_port, out_port, data) # src and dst on the same datapath else: out_port = self.get_port(flow_info[2], access_table) self.logger.info("[DEBUG][MAIN_APP][install_flow] esle: outport %s, dst_ip: %s", out_port, flow_info[2]) if out_port is None: self.logger.info("Out_port is None in same dp") return self.send_flow_mod(first_dp, flow_info, in_port, out_port) self.send_flow_mod(first_dp, back_info, out_port, in_port) self.send_packet_out(first_dp, buffer_id, in_port, out_port, data)
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