ping <host> mtu-discovery < do | dont | want > <option>
Selects the discovery strategy of the path maximum transmission unit (PMTU).
- ipv4_address
- The IPv4 address of the host.
- ipv6_address
- The IPv6 address of the host.
- hostname
- A host being pinged. This keyword is used when the host is specified as a host name rather than as an IP address.
- do
Prohibits fragmentation, even for the local packet. Sets a do-not fragment (DF) flag to the router.
- want
Performs a PMTU discovery. During the discovery the device fragments the packet locally.
- dont
- Prohibits fragmentation, but does not set a DF flag.
- option
- Each of the following entries are considered options. These options can be issued consecutively, that is, in the same command line.
- adaptive
- Adaptively sets interpacket interval.
- allow-broadcast
- Allows you to ping broadcast address.
- audible
- Makes a beep sound on every ping, while the device pings for host details.
- bypass-route
- Bypasses normal routing tables during ping.
- count
- Specifies the number of ping requests to send.
- deadline
- Specifies the number of seconds before which ping expires.
- ether-size
- Matches the overall size of the data packet with the resultant size of the Layer 3 packet.
- flood
- Sends 100 ping requests each second.
- interface
- Specifies an interface that the device must use as the source address.
- interval
- Specifies the time in seconds for which the device must wait between ping requests.
- mark
- Specifies that the device must consider the ping request for special processing.
- mtu-discovery
- Specifies the path MTU discovery strategy.
- no-loopback
- Suppresses loop-back of multicast pings.
- numeric
- Does not resolve domain name system (DNS) names during ping.
- pattern
- Specifies the hexadecimal digit pattern to fill the packet.
- quiet
- Prints only the ping summary page.
- record-route
- Records the route that the packet takes.
- size
- Specifies the number of bytes to send for a ping request.
- timestamp
- Displays the timestamp during ping output.
- tos
- Marks packet with specified type of service (TOS).
- ttl
- Specifies the maximum packet life-time for a host.
- verbose
- Displays a detailed output for the ping command.
Operational mode
The ping host mtu-discovery command selects the discovery strategy of the PMTU, based on the parameters provided. The command checks the size of the packet. If the size is equal to or greater than the maximum data payload that is available in a packet, the device determines whether the packet has to be fragmented, based on the discovery strategy of the PMTU.
This example shows how to test 1472 bytes of data of the host 10.0.0.103 for network reachability while prohibiting network fragmentation during the ping. However a do-not-fragment flag is set for the router.
vyatta@vyatta:~$ ping 10.0.0.103 size 1472 mtu-discovery do
PING 10.0.0.103 (10.0.0.103) 1472(1500) bytes of data.
1480 bytes from 10.0.0.103: icmp_req=1 ttl=64 time=0.923 ms
^[[A1480 bytes from 10.0.0.103: icmp_req=2 ttl=64 time=1.35 ms
^C
--- 10.0.0.103 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.923/1.137/1.352/0.217 msThis example shows how to test 1472 bytes of data of the host 10.0.0.103 for network reachability while prohibiting network fragmentation during the ping. However a do-not-fragment flag is not set for the router.
vyatta@VR-1:~$ ping 10.0.0.103 size 1472 mtu-discovery dont
PING 10.0.0.103 (10.0.0.103) 1472(1500) bytes of data.
1480 bytes from 10.0.0.103: icmp_req=1 ttl=64 time=1.25 ms
^C
--- 10.0.0.103 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 1.250/1.250/1.250/0.000 msThis example shows how to perform a discovery strategy for PMTU during a ping request. During the discovery, the router fragments the packet locally.
vyatta@VR-1:~$ ping 10.0.0.103 size 1472 mtu-discovery want
PING 10.0.0.103 (10.0.0.103) 1472(1500) bytes of data.
1480 bytes from 10.0.0.103: icmp_req=1 ttl=64 time=1.00 ms
^C
--- 10.0.0.103 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 1.005/1.005/1.005/0.000 ms