-bash-2.05b$ ping 10.0.0.10 PING 10.0.0.10 (10.0.0.10): 56 data bytes 64 bytes from 10.0.0.10: icmp_seq=0 ttl=64 time=348.357 ms 64 bytes from 10.0.0.10: icmp_seq=1 ttl=64 time=102.029 ms 64 bytes from 10.0.0.10: icmp_seq=2 ttl=64 time=173.259 ms 64 bytes from 10.0.0.10: icmp_seq=3 ttl=64 time=91.563 ms 64 bytes from 10.0.0.10: icmp_seq=4 ttl=64 time=15.967 ms 64 bytes from 10.0.0.10: icmp_seq=5 ttl=64 time=17.462 ms 64 bytes from 10.0.0.10: icmp_seq=6 ttl=64 time=17.581 ms 64 bytes from 10.0.0.10: icmp_seq=7 ttl=64 time=16.970 ms 64 bytes from 10.0.0.10: icmp_seq=8 ttl=64 time=17.470 ms 64 bytes from 10.0.0.10: icmp_seq=9 ttl=64 time=17.176 ms 64 bytes from 10.0.0.10: icmp_seq=10 ttl=64 time=16.752 ms 64 bytes from 10.0.0.10: icmp_seq=11 ttl=64 time=26.070 ms 64 bytes from 10.0.0.10: icmp_seq=12 ttl=64 time=17.016 ms 64 bytes from 10.0.0.10: icmp_seq=13 ttl=64 time=26.679 ms 64 bytes from 10.0.0.10: icmp_seq=14 ttl=64 time=16.491 ms 64 bytes from 10.0.0.10: icmp_seq=15 ttl=64 time=16.772 ms 64 bytes from 10.0.0.10: icmp_seq=16 ttl=64 time=74.116 ms 64 bytes from 10.0.0.10: icmp_seq=17 ttl=64 time=33.907 ms 64 bytes from 10.0.0.10: icmp_seq=18 ttl=64 time=16.042 ms 64 bytes from 10.0.0.10: icmp_seq=19 ttl=64 time=15.823 ms 64 bytes from 10.0.0.10: icmp_seq=20 ttl=64 time=15.551 ms 64 bytes from 10.0.0.10: icmp_seq=21 ttl=64 time=17.685 ms 64 bytes from 10.0.0.10: icmp_seq=22 ttl=64 time=342.507 ms 64 bytes from 10.0.0.10: icmp_seq=23 ttl=64 time=110.026 ms 64 bytes from 10.0.0.10: icmp_seq=24 ttl=64 time=69.728 ms 64 bytes from 10.0.0.10: icmp_seq=25 ttl=64 time=30.467 ms 64 bytes from 10.0.0.10: icmp_seq=26 ttl=64 time=15.708 ms 64 bytes from 10.0.0.10: icmp_seq=27 ttl=64 time=17.404 ms 64 bytes from 10.0.0.10: icmp_seq=28 ttl=64 time=17.641 ms 64 bytes from 10.0.0.10: icmp_seq=29 ttl=64 time=16.363 ms 64 bytes from 10.0.0.10: icmp_seq=30 ttl=64 time=17.851 ms 64 bytes from 10.0.0.10: icmp_seq=31 ttl=64 time=25.214 ms 64 bytes from 10.0.0.10: icmp_seq=32 ttl=64 time=107.697 ms 64 bytes from 10.0.0.10: icmp_seq=33 ttl=64 time=177.524 ms 64 bytes from 10.0.0.10: icmp_seq=34 ttl=64 time=97.248 ms 64 bytes from 10.0.0.10: icmp_seq=35 ttl=64 time=54.683 ms 64 bytes from 10.0.0.10: icmp_seq=36 ttl=64 time=16.080 ms ^C --- 10.0.0.10 ping statistics --- 37 packets transmitted, 37 packets received, 0% packet loss round-trip min/avg/max/stddev = 15.551/60.186/348.357/80.744 ms
The beginning of a ping sequence always looks this way (high latency). I have only guessed that it is due to communication setup between the AP and end-points, but I'm not sure. As you can see, the fluctuations to higher latency are semi-regular. The MP.11 gear uses a type of wireless protocol they call WORP to deal with hidden-node and "collisions" in a wireless network. From their manual:
"The Wireless Outdoor Router Protocol (WORP) is a polling algorithm designed for wireless outdoor networks. WORP takes care of the performance degradation incurred by the so-called “hidden-node” problem, which can occur when standards-based 802.11b wireless LAN technology is used for outdoor building-to-building connectivity. In this situation, when multiple radios send an RTS, if another radio is transmitting, it corrupts all data being sent, degrading overall performance. The WORP polling algorithm ensures that these collisions cannot occur, which increases the performance of the overall network significantly. WORP dynamically adapts to the number of satellites that are active on the network and the amount of data they have queued to send."
It seems to me that this protocol actually adds latency to the network by buffering data before being sent (i.e. by making sure that no one else is transmitting at the same time). What my real question is, is whether you are seeing that type of latency on normal bridges - or really, across a number of bridges? Has anyone done studies on how to reduce latency between nodes and/or what are some tricks used? I may be stuck with the latency (although "stuck" is perhaps harsh - performance with surfing, etc. fine - it is if people want to start using VoIP that I am concerned about) with the Tsunami MP.11 gear, but I want to find out whether this type of latency is typical for an outdoor/long-distance wireless network. I had a neighborhood co-op set up using a lot of hacked consumer equipment, but we never did latency tests because I wasn't too concerned about QoS, just general bandwidth availability, etc.
Any ideas, comments, etc. are much appreciated.
Thanks, Steve Fettig _______________________________________________ BAWUG's general wireless chat mailing list [unsubscribe] http://lists.bawug.org/mailman/listinfo/wireless
