¶ Contents
¶ Useful Commands
¶ Switches
| Command | Description |
|---|---|
show clock |
Print the current system time |
show tech-support |
Outputs settings, errors etc needed for technical support purposes. You'll need to ensure that the SSH/Telnet client is logging output to a local text file |
show interface status |
Outputs the status of all interfaces |
These commands work on both Cisco and OS10 devices, but check documentation first
¶ OS troubleshooting commands
¶ Linux
| Command | Description | Use case |
|---|---|---|
ip a |
Shows IP configuration | For use when IP settings are unknown. Will also show MTU settings. NOTE: Can add -c to add colour which makes it easier to read |
ping -M do -s [DATA BYTES] [HOST] |
pings [HOST] with -s [DATA BYTES] with the "Do not fragment" flag set using -M do |
Troubleshoot MTU config issues. [DATA BYTES] is the payload of the packet and does not include ethernet/IP headers etc |
¶ Windows
| Command | Description | Use case |
|---|---|---|
netsh interface ipv4 show subinterfaces |
Lists out status of adapters including link state, MTU etc | Discovery of MTU settings. |
ping -l [DATA BYTES] -f [HOST] |
Pings [HOST] with -l [DATA BYTES] with the "Do not fragment" flag set with -f |
Troubleshoot MTU config issues. [DATA BYTES] is the payload of the packet and does not include ethernet/IP headers etc Use 8972 bytes to test for MTU of 9000. 8792 is frame size minus header info |
¶ VMware
| Command | Description | Use case |
|---|---|---|
vmkping -s [DATA BYTES] -d [HOST] |
Pings [HOST] with -s [DATA BYTES] with the "Do not fragment" flag set -d |
Troubleshoot MTU config issues. [DATA BYTES] is the payload of the packet and does not include ethernet/IP headers etc |
¶ TCP IP
¶ TCP Handshake
sequenceDiagram
Client->>+Server: SYN
Server->>-Client: SYN-ACK
Client->>+Server: ACK
¶ Packet Info
| Item | Explanation |
|---|---|
| TTL (time to live) | Number of hops before the packet is lost (prevents packets from going round and round without ever reaching destination) |
| Hop Limit | IPv6 equivalent of TTL |
¶ Infiniband
¶ General Troubleshooting
| Tool | source | Purpose |
|---|---|---|
| sysinfo-snapshot | https://github.com/Mellanox/linux-sysinfo-snapshot | Take a snapshot of all the configuration and relevant information on the server and Mellanox's adapters. |
| ibdiagnet | https://docs.nvidia.com/networking/display/ibdiagnetUserManualv10/ibdiagnet+Functionality ibutils package |
Sweeps the InfiniBand fabric and collects information from the following InfiniBand devices:
|
| switch configuration | ??? | Obtain the configuration settings of the switch |
¶ Other
Nvidia developer forums: https://forums.developer.nvidia.com/c/infrastructure/369/
¶ Troubleshooting VLAN
