управление метриками TCP (management for TCP Metrics)
Имя (Name)
ip-tcp_metrics - management for TCP Metrics
Синопсис (Synopsis)
ip [ OPTIONS ] tcp_metrics { COMMAND | help }
ip tcp_metrics { show | flush } SELECTOR
ip tcp_metrics delete [ address ] ADDRESS
SELECTOR := [ [ address ] PREFIX ]
Описание (Description)
ip tcp_metrics is used to manipulate entries in the kernel that
keep TCP information for IPv4 and IPv6 destinations. The entries
are created when TCP sockets want to share information for
destinations and are stored in a cache keyed by the destination
address. The saved information may include values for metrics
(initially obtained from routes), recent TSVAL for TIME-WAIT
recycling purposes, state for the Fast Open feature, etc. For
performance reasons the cache can not grow above configured limit
and the older entries are replaced with fresh information,
sometimes reclaimed and used for new destinations. The kernel
never removes entries, they can be flushed only with this tool.
ip tcp_metrics show - show cached entries
address PREFIX (default)
IPv4/IPv6 prefix or address. If no prefix is provided all
entries are shown.
The output may contain the following information:
age <S.MMM>sec - time after the entry was created, reset or
updated with metrics from sockets. The entry is reset and
refreshed on use with metrics from route if the metrics are not
updated in last hour. Not all cached values reset the age on
update.
cwnd <N> - CWND metric value
fo_cookie <HEX-STRING> - Cookie value received in SYN-ACK to be
used by Fast Open for next SYNs
fo_mss <N> - MSS value received in SYN-ACK to be used by Fast
Open for next SYNs
fo_syn_drops <N>/<S.MMM>sec ago - Number of drops of initial
outgoing Fast Open SYNs with data detected by monitoring the
received SYN-ACK after SYN retransmission. The seconds show the
time after last SYN drop and together with the drop count can be
used to disable Fast Open for some time.
reordering <N> - Reordering metric value
rtt <N>us - RTT metric value
rttvar <N>us - RTTVAR metric value
ssthresh <SSTHRESH> - SSTHRESH metric value
tw_ts <TSVAL>/<SEC>sec ago - recent TSVAL and the seconds after
saving it into TIME-WAIT socket
ip tcp_metrics delete - delete single entry
address ADDRESS (default)
IPv4/IPv6 address. The address is a required argument.
ip tcp_metrics flush - flush entries
This command flushes the entries selected by some criteria.
This command has the same arguments as show.
Примеры (Examples)
ip tcp_metrics show address 192.168.0.0/24
Shows the entries for destinations from subnet
ip tcp_metrics show 192.168.0.0/24
The same but address keyword is optional
ip tcp_metrics
Show all is the default action
ip tcp_metrics delete 192.168.0.1
Removes the entry for 192.168.0.1 from cache.
ip tcp_metrics flush 192.168.0.0/24
Removes entries for destinations from subnet
ip tcp_metrics flush all
Removes all entries from cache
ip -6 tcp_metrics flush all
Removes all IPv6 entries from cache keeping the IPv4 entries.
Смотри также (See also)
ip(8)
