Changes between Version 17 and Version 18 of GENIExperimenter/Tutorials/OpenFlowNetworkDevices/NAT
- Timestamp:
- 07/08/16 11:48:13 (8 years ago)
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GENIExperimenter/Tutorials/OpenFlowNetworkDevices/NAT
v17 v18 110 110 111 111 == 3 Handle ARP and ICMP == 112 One of very common mistakes that people make, when writing OF controller, is forgetting to handle ARP and ICMP message and finding their controller doesnot work as expected.112 One common mistake experimenters make, when writing OpenFlow controllers, is forgetting to handle ARP and ICMP message causing their controllers to not work as expected. 113 113 114 === 3.1 ARP === 115 As we mentioned before, we should insert rules into the OF switch that allow ARP packets to go through, probably after the switch is connected. 114 Handling ARP is trivial in this example, as NAT does not involve ARP. However, that is not the case for ICMP. If you only process translations for TCP/UDP, you will find you cannot ping between `outside` and `insideX`, though nc is working properly. Handling ICMP is not as straightforward as for TCP/UDP because for ICMP you cannot get port information to bind with. Our provided solution makes use of the ICMP echo identifier. You could come up with different approach using ICMP sequence numbers, etc. To see ICMP working do the following. 116 115 117 === 3.2 ICMP === 118 Handling ARP is trivial as NAT does not involve ARP. However, it's not the case for ICMP. If you only process translation for TCP/UDP, you will find you cannot ping between `outside` and `insideX` while nc is working properly. Handling ICMP is even not as straightforward as for TCP/UDP. Because for ICMP, you cannot get port information to bind with. Our provided solution makes use of ICMP echo identifier. You may come up with different approach involves ICMP sequence number or others. 119 120 a. On `inside1`, start a ping to `outside`. 116 a. On `inside1`, start pinging `outside`. 121 117 {{{ 122 118 inside1:~$ ping 128.128.128.2 … … 128 124 }}} 129 125 130 You should see both ping ingare working.126 You should see both ping commands are working. 131 127 132 128 c. On `outside`, use `tcpdump` to check the packets it receives. … … 135 131 }}} 136 132 137 You should see it's receiving two groups of icmp packets, differentiated by id.133 Notice that it is receiving two groups of icmp packets, differentiated by id. 138 134 139 135 = [.. Return to the main page] =
