1omping(8) System Manager's Manual omping(8)
3
7 omping - test IP multicast
8
10 ping [-46FVv] [-i interval] [-m mcast_addr] [-p port] [-t ttl]
11 remote_addr...
12
14 omping is program which uses User Datagram Protocol to determine if
15 computer is able to send and/or receive IP Unicast and Multicast pack‐
16 ets from the network. It's designed to be used in very similar way as
17 ping(8) and also has some features of the fping(8) command. Where
18 ping(8) and omping differ is in who replies. In ping(8) replies are
19 sent by the operating system and with omping another instance of omping
20 sends the reply. This mean that omping must be running on all comput‐
21 ers to test sending/receiving IP Multicast.
22 Omping(8) uses Internet-Draft draft-ietf-mboned-ssmping-08 as underlay‐
24 ing protocol and tries to be as compliant as possible.
25
27 -4 Force usage of IPv4.
28 -6 Force usage of IPv6.
30 -F Allow entering of arguments which are not allowed or not recom‐
32 mended by the specification. This is typically the interval
33 parameter. This option may be used multiple times.
34 -V Display version and quit.
36 -v Set level of verbosity. Parameter can be used multiple times to
38 achieve higher verbosity.
39 -i interval
41 Wait interval seconds between sending each request packet. The
42 default is to wait for one second between each packet.
43 -m mcast_addr
45 Multicast address to listen on for multicast answer messages.
46 Default is 232.43.211.234 for IPv4 and ff3e::4321:1234 for IPv6.
47 -p port
49 Port to bind and listen on for both unicast and multicast mes‐
50 sages. Default is 4321.
51 -t ttl Time-To-Live of sent packets.
53 remote_addr
55 List of addresses to test. One of them must be address of local
56 internet interface. This local address is used for bind and lis‐
57 tening on for unicast packets. It's also used to determine which
58 interface should be used for sending multicast replies.
59
61 The following commands and output is a typical way how to find-out and
62 solve network problems using omping. In this situation, we have 3 com‐
63 puters named node-01, node-02 and node-03 with IP addresses
64 192.168.1.101 - 192.168.1.103. Let's run the following command on all
65 of them.
66 $ omping node-01 node-02 node-03
68 on all of nodes we should be able to seen similar output
70 node-01 : waiting for response msg
72 node-03 : waiting for response msg
73 node-01 : joined (S,G) = (*, 232.43.211.234), pinging
74 node-03 : joined (S,G) = (*, 232.43.211.234), pinging
75 node-01 : unicast, seq=1, size=69 bytes, dist=0, time=0.192ms (0.192 avg, 0% loss)
76 node-01 : multicast, seq=1, size=69 bytes, dist=0, time=0.284ms (0.284 avg, 0% loss)
77 node-03 : unicast, seq=1, size=69 bytes, dist=0, time=0.279ms (0.279 avg, 0% loss)
78 node-03 : multicast, seq=1, size=69 bytes, dist=0, time=0.360ms (0.360 avg, 0% loss)
79 The first two lines tell us, that node-02 (actual node) is waiting for
81 a response message from node-01 and node-03. The second two lines con‐
82 tain information, that we were successfully able to send an init mes‐
83 sage and also received a response message from remote nodes. Both of
84 these messages are unicast, so we are able to send and receive unicast
85 messages on a given port. If all of nodes are up and omping is running
86 on all of them, but we are not able to receive a response message, it's
87 time to check connectivity between nodes. First make sure that you are
88 able to ping(8) them. If so, make sure that your firewall allows port
89 4321 to receive udp packets.
90 The next line tells us that we were able to receive a 69 byte unicast
92 response message from node-01, with a sequence number of 1. The dis‐
93 tance between the computers is 0 so they are on the same link net. Time
94 between send and receive packet was 0.192 ms, that is also the current
95 average time and lastly there were no lost packets.
96 The 6th line tells us the same information as the previous one, but the
98 received message is a multicast message. It means, that multicast is
99 probably well configured.
100 The 7th and 8th lines are same as previous two one but for node-03.
102 If the node is able to receive unicast packets, but never multicast, it
104 means that multicast configuration is incorrect. It's recommended to
105 turn off your firewall. If multicast packets start to arrive, great. If
106 not, the problem is hidden in the switches/routers between the nodes.
107 Contact your system administrator to allow multicast traffic on the
108 switch or router.
109 omping is terminated by SIGINT signal (CTRL-c). Summary statistics are
111 shown
112 node-01 : unicast, xmt/rcv/%loss = 389/389/0%, min/avg/max = 0.267/0.289/0.386
114 node-01 : multicast, xmt/rcv/%loss = 389/389/0%, min/avg/max = 0.306/0.332/0.540
115 node-03 : unicast, xmt/rcv/%loss = 289/289/0%, min/avg/max = 0.262/0.284/0.365
116 node-03 : multicast, xmt/rcv/%loss = 289/289/0%, min/avg/max = 0.325/0.356/0.548
117
119 · Packet duplicate detection is not implemented.
120 · SSM multicast is not implemented.
122 · Actually computed RTT is not RTT taken from packet, but end-to-end
124 delivery.
125 · It's impossible to set size of send/receive buffer.
127 · No quite mode.
129 · No count mode.
131
133 ping(8), fping(8)
134
136 Jan Friesse
137 2010-11-18 omping(8)