2015-10-16 07:03:16 +00:00
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---
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layout: "docs"
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page_title: "Commands: RTT"
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sidebar_current: "docs-commands-rtt"
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description: >
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The rtt command estimates the network round trip time between two nodes.
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---
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# Consul RTT
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Command: `consul rtt`
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The 'rtt' command estimates the network round trip time between two nodes using
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Consul's network coordinate model of the cluster. While contacting nodes as part
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of its normal gossip protocol, Consul builds up a set of network coordinates for
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all the nodes in the local datacenter (the LAN pool) and remote datacenters (the WAN
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pool). Agents forward these to the servers and once the coordinates for two nodes
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are known, it's possible to estimate the network round trip time between them using
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a simple calculation.
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It is not possible to measure between LAN coordinates and WAN coordinates
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because they are maintained by independent Serf gossip pools, so they are
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not compatible.
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## Usage
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Usage: `consul rtt [options] node1 node2`
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The two node names are required. Note that these are node names as known to
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Consul as `consul members` would show, not IP addresses.
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The list of available flags are:
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* `-wan` - Instructs the command to use WAN coordinates instead of LAN
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coordinates. If the -wan option is given, then the node names must be prefixed
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by the datacenter and a period (eg. "dc1.sever"). By default, the two nodes are
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assumed to be nodes in the local datacenter the LAN coordinates are used.
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* `-short` - Abbreviates the output to just the round trip time (eg. "1.234 ms").
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* `-http-addr` - Address to the HTTP server of the agent you want to contact
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to send this command. If this isn't specified, the command will contact
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"127.0.0.1:8500" which is the default HTTP address of a Consul agent.
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## Output
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If coordinates are available, the command will print the estimated round trip
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time between the given nodes:
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```
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$ consul rtt n1 n2
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Estimated n1 <-> n2 rtt=0.610 ms (using LAN coordinates)
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2015-10-16 07:56:15 +00:00
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$ consul rtt -short n1 n2
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0.610 ms
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2015-10-16 07:03:16 +00:00
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$ consul rtt -wan dc1.n1 dc2.n2
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Estimated dc1.n1 <-> dc2.n2 rtt=1.275 ms (using WAN coordinates)
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```
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