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ea63a69b JA |
1 | .TH "IP\-TCP_METRICS" 8 "23 Aug 2012" "iproute2" "Linux" |
2 | .SH "NAME" | |
3 | ip-tcp_metrics \- management for TCP Metrics | |
4 | .SH "SYNOPSIS" | |
5 | .sp | |
6 | .ad l | |
7 | .in +8 | |
8 | .ti -8 | |
9 | .B ip | |
10 | .RI "[ " OPTIONS " ]" | |
11 | .B tcp_metrics | |
12 | .RI "{ " COMMAND " | " | |
13 | .BR help " }" | |
14 | .sp | |
15 | ||
16 | .ti -8 | |
17 | .BR "ip tcp_metrics" " { " show " | " flush " } | |
18 | .IR SELECTOR | |
19 | ||
20 | .ti -8 | |
21 | .BR "ip tcp_metrics delete " [ " address " ] | |
22 | .IR ADDRESS | |
23 | ||
24 | .ti -8 | |
25 | .IR SELECTOR " := " | |
26 | .RB "[ [ " address " ] " | |
27 | .IR PREFIX " ]" | |
28 | ||
29 | .SH "DESCRIPTION" | |
30 | .B ip tcp_metrics | |
31 | is used to manipulate entries in the kernel that keep TCP information | |
32 | for IPv4 and IPv6 destinations. The entries are created when | |
33 | TCP sockets want to share information for destinations and are | |
34 | stored in a cache keyed by the destination address. The saved | |
35 | information may include values for metrics (initially obtained from | |
36 | routes), recent TSVAL for TIME-WAIT recycling purposes, state for the | |
37 | Fast Open feature, etc. | |
38 | For performance reasons the cache can not grow above configured limit | |
39 | and the older entries are replaced with fresh information, sometimes | |
40 | reclaimed and used for new destinations. The kernel never removes | |
41 | entries, they can be flushed only with this tool. | |
42 | ||
43 | .SS ip tcp_metrics show - show cached entries | |
44 | ||
45 | .TP | |
46 | .BI address " PREFIX " (default) | |
47 | IPv4/IPv6 prefix or address. If no prefix is provided all entries are shown. | |
48 | ||
49 | .LP | |
50 | The output may contain the following information: | |
51 | ||
52 | .BI age " <S.MMM>" sec | |
53 | - time after the entry was created, reset or updated with metrics | |
54 | from sockets. The entry is reset and refreshed on use with metrics from | |
55 | route if the metrics are not updated in last hour. Not all cached values | |
56 | reset the age on update. | |
57 | ||
58 | .BI cwnd " <N>" | |
59 | - CWND metric value | |
60 | ||
61 | .BI fo_cookie " <HEX-STRING>" | |
62 | - Cookie value received in SYN-ACK to be used by Fast Open for next SYNs | |
63 | ||
64 | .BI fo_mss " <N>" | |
65 | - MSS value received in SYN-ACK to be used by Fast Open for next SYNs | |
66 | ||
67 | .BI fo_syn_drops " <N>/<S.MMM>" "sec ago" | |
68 | - Number of drops of initial outgoing Fast Open SYNs with data | |
69 | detected by monitoring the received SYN-ACK after SYN retransmission. | |
70 | The seconds show the time after last SYN drop and together with | |
71 | the drop count can be used to disable Fast Open for some time. | |
72 | ||
73 | .BI reordering " <N>" | |
74 | - Reordering metric value | |
75 | ||
76 | .BI rtt " <N>" us | |
77 | - RTT metric value | |
78 | ||
79 | .BI rttvar " <N>" us | |
80 | - RTTVAR metric value | |
81 | ||
82 | .BI ssthresh " <SSTHRESH>" | |
83 | - SSTHRESH metric value | |
84 | ||
85 | .BI tw_ts " <TSVAL>/<SEC>" "sec ago" | |
86 | - recent TSVAL and the seconds after saving it into TIME-WAIT socket | |
87 | ||
88 | .SS ip tcp_metrics delete - delete single entry | |
89 | ||
90 | .TP | |
91 | .BI address " ADDRESS " (default) | |
92 | IPv4/IPv6 address. The address is a required argument. | |
93 | ||
94 | .SS ip tcp_metrics flush - flush entries | |
95 | This command flushes the entries selected by some criteria. | |
96 | ||
97 | .PP | |
98 | This command has the same arguments as | |
99 | .B show. | |
100 | ||
101 | .SH "EXAMPLES" | |
102 | .PP | |
103 | ip tcp_metrics show address 192.168.0.0/24 | |
104 | .RS 4 | |
105 | Shows the entries for destinations from subnet | |
106 | .RE | |
107 | .PP | |
108 | ip tcp_metrics show 192.168.0.0/24 | |
109 | .RS 4 | |
110 | The same but address keyword is optional | |
111 | .RE | |
112 | .PP | |
113 | ip tcp_metrics | |
114 | .RS 4 | |
115 | Show all is the default action | |
116 | .RE | |
117 | .PP | |
118 | ip tcp_metrics delete 192.168.0.1 | |
119 | .RS 4 | |
120 | Removes the entry for 192.168.0.1 from cache. | |
121 | .RE | |
122 | .PP | |
123 | ip tcp_metrics flush 192.168.0.0/24 | |
124 | .RS 4 | |
125 | Removes entries for destinations from subnet | |
126 | .RE | |
127 | .PP | |
128 | ip tcp_metrics flush all | |
129 | .RS 4 | |
130 | Removes all entries from cache | |
131 | .RE | |
132 | .PP | |
133 | ip -6 tcp_metrics flush all | |
134 | .RS 4 | |
135 | Removes all IPv6 entries from cache keeping the IPv4 entries. | |
136 | .RE | |
137 | ||
138 | .SH SEE ALSO | |
139 | .br | |
140 | .BR ip (8) | |
141 | ||
142 | .SH AUTHOR | |
143 | Original Manpage by Julian Anastasov <ja@ssi.bg> |