Sorry for my unclear statement. I’m using the discovery, STP, l2_multi modules on the controller with the diamond topology, like
h1—s0—— s1—— s2—h3 | | | ——s3—— | When I issue a ping on h1 (10.0.0.1) like this ------------------- root@ubuntu:~# ping 10.0.0.3 -s 1600 PING 10.0.0.3 (10.0.0.3) 1600(1628) bytes of data. ^C --- 10.0.0.3 ping statistics --- 14 packets transmitted, 0 received, 100% packet loss, time 13102ms —————————— The ping can never be successful. By default, I can’t see any warning or error log information on pox. If you ping with smaller size packet like 1000 bytes, there isn't any problem. After I tested, the threshold is around 1500, I’m thinking it’s because of fragmentation. ————————————————————— root@ubuntu:~# ping 10.0.0.3 -s 1000 PING 10.0.0.3 (10.0.0.3) 1000(1028) bytes of data. 1008 bytes from 10.0.0.3: icmp_req=1 ttl=64 time=268 ms 1008 bytes from 10.0.0.3: icmp_req=2 ttl=64 time=0.061 ms 1008 bytes from 10.0.0.3: icmp_req=3 ttl=64 time=0.052 ms 1008 bytes from 10.0.0.3: icmp_req=4 ttl=64 time=0.057 ms ———————————————— Here is the all log information on the pox side. ———————————— pox git:(dart) ./pox.py openflow.discovery openflow.spanning_tree forwarding.l2_multi POX 0.3.0 (dart) / Copyright 2011-2014 James McCauley, et al. INFO:core:POX 0.3.0 (dart) is up. INFO:openflow.of_01:[00-00-00-00-00-0c 1] connected INFO:openflow.of_01:[00-00-00-00-00-0d 4] connected INFO:openflow.of_01:[00-00-00-00-00-0b 2] connected INFO:openflow.of_01:[00-00-00-00-00-0a 3] connected INFO:openflow.discovery:link detected: 00-00-00-00-00-0c.3 -> 00-00-00-00-00-0d.2 INFO:openflow.discovery:link detected: 00-00-00-00-00-0c.2 -> 00-00-00-00-00-0b.3 INFO:openflow.discovery:link detected: 00-00-00-00-00-0d.3 -> 00-00-00-00-00-0a.3 INFO:openflow.discovery:link detected: 00-00-00-00-00-0d.2 -> 00-00-00-00-00-0c.3 INFO:openflow.spanning_tree:6 ports changed INFO:openflow.discovery:link detected: 00-00-00-00-00-0b.3 -> 00-00-00-00-00-0c.2 INFO:openflow.spanning_tree:4 ports changed INFO:openflow.discovery:link detected: 00-00-00-00-00-0b.2 -> 00-00-00-00-00-0a.2 INFO:openflow.spanning_tree:1 ports changed INFO:openflow.discovery:link detected: 00-00-00-00-00-0a.3 -> 00-00-00-00-00-0d.3 INFO:openflow.spanning_tree:4 ports changed INFO:openflow.discovery:link detected: 00-00-00-00-00-0a.2 -> 00-00-00-00-00-0b.2 ————————————————————— Using Ryu as the controller for the same topology ——— ———— ————— root@ubuntu:~# ping 10.0.0.3 -s 9999 PING 10.0.0.3 (10.0.0.3) 9999(10027) bytes of data. 10007 bytes from 10.0.0.3: icmp_req=21 ttl=64 time=1.36 ms 10007 bytes from 10.0.0.3: icmp_req=22 ttl=64 time=0.183 ms 10007 bytes from 10.0.0.3: icmp_req=23 ttl=64 time=0.118 ms 10007 bytes from 10.0.0.3: icmp_req=24 ttl=64 time=0.142 ms 10007 bytes from 10.0.0.3: icmp_req=25 ttl=64 time=0.259 ms 10007 bytes from 10.0.0.3: icmp_req=26 ttl=64 time=0.150 ms 10007 bytes from 10.0.0.3: icmp_req=27 ttl=64 time=0.122 ms 10007 bytes from 10.0.0.3: icmp_req=28 ttl=64 time=0.109 ms 10007 bytes from 10.0.0.3: icmp_req=29 ttl=64 time=0.265 ms ————— ————————— > On Oct 19, 2014, at 19:42, Murphy McCauley <murphy.mccau...@gmail.com> wrote: > > I don't know what limit you're running into. > > Can you be (much) more specific about what you're trying to do, what you > think should be happening, what is happening instead, any relevant errors or > log messages, etc.? > > -- Murphy > > On Oct 19, 2014, at 4:35 PM, Tim Huang <pds...@gmail.com> wrote: > >> Hi, >> >> I am modifying the pox code to perform some kind of load balancing on the >> controller. However, I found that the maximum ping packet size that pox can >> handle is around 1500 bytes which is too small for my test case, then I >> tried other controllers like Ryu, Opendaylight, and they don’t have this >> kind of limitation. Is it because of fragmentation or something else? any >> clue for this? >