MTU
Maximum Transmission Unit (MTU) is the largest size in bytes that a certain layer can forward. The MTU is different for each protocol and medium that we use. Ethernet for example has a MTU of 1500 bytes by default.
This means that a single Ethernet frame can carry up to 1500 bytes of data. On top of this data we add the Ethernet header. Typical header sizes are 14 bytes for Ethernet (add another 4 bytes if you use 802.1Q tagging).
The following image indicates the different MTUs that are used for various layers of the OSI model when using TCP/IP and Ethernet:
Links:
https://networklessons.com/cisco/ccie-routing-switching/pppoe-mtu-troubleshooting-cisco-ios
Links to this page:
- Equal-cost Multi-path routing
- Ethernet header
- GRE MTU settings
- ICMP - Mitigating Vulnerabilities
- Interface - show interfaces counters explained
- MTU - Adjusting MTU to accommodate additional headers
- MTU - Interface MTU configuration considerations
- MTU - MSS and Jumbo Frames
- MTU - Path MTU Discovery (PMTUD)
- MTU - default interface MTU
- MTU adjusting the MSS for TCP
- MTU ip mtu allowed values
- MTU on Etherchannel links
- MTU on router subinterfaces
- MTU size in Cisco IOS XR and IOS software
- Ping - sweep range of sizes
- UDP - Maximum Datagram Size
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