Ethernet Mtu; Mac Address - Cisco ASR 9000 Series Configuration Manuallines

The Carrier Ethernet Model
IEEE 802.3ae 10 Gbps Ethernet
Under the International Standards Organization's Open Systems Interconnection (OSI) model, Ethernet is
fundamentally a L2 protocol. 10-Gigabit Ethernet uses the IEEE 802.3 Ethernet MAC protocol, the IEEE
802.3 Ethernet frame format, and the minimum and maximum IEEE 802.3 frame size. 10 Gbps Ethernet
conforms to the IEEE 802.3ae protocol standards.
Just as 1000BASE-X and 1000BASE-T (Gigabit Ethernet) remained true to the Ethernet model, 10-Gigabit
Ethernet continues the natural evolution of Ethernet in speed and distance. Because it is a full-duplex only
and fiber-only technology, it does not need the carrier-sensing multiple-access with the CSMA/CD protocol
that defines slower, half-duplex Ethernet technologies. In every other respect, 10-Gigabit Ethernet remains
true to the original Ethernet model.
General Ethernet Standards
• Ethernet II framing also known as DIX.
• IEEE 802.3 framing also includes LLC and LLC/SNAP protocol frame formats.
• IEEE 802.1d MAC Bridges and Spanning Tree—This standard specifies the MAC learning and MAC
• IEEE 802.1q VLAN tagging—This standard defines VLAN tagging, and also the traditional VLAN
• IEEE 802.1ad Provider Bridges—This standard is a subset of 802.1q and is often referred to as 802.1ad.

MAC Address

A MAC address is a unique 6-byte address that identifies the interface at L2.

Ethernet MTU

The Ethernet Maximum Transmission Unit (MTU) is the size of the largest frame, minus the 4-byte Frame
Check Sequence (FCS), that can be transmitted on the Ethernet network. Every physical network along the
destination of a packet can have a different MTU.
Cisco IOS XR software supports two types of frame forwarding processes:
• Fragmentation for IPV4 packets—In this process, IPv4 packets are fragmented as necessary to fit within
• MTU discovery process determines largest packet size—This process is available for all IPV6 devices,
aging in a bridging environment. It also defines the original spanning tree protocol. Also MSTP is defined
in IEEE 802.1s and IEEE 802.1q.
trunking between switches. Technically, it also defines QinQ tagging, and MSTP. The Cisco ASR 9000
Series Routers do NOT support ISL.
The Cisco ASR 9000 Series Routers do not adhere to the entire standard, but large portions of the
standard's functionality are supported.
the MTU of the next-hop physical network.
Note IPv6 does not support fragmentation.
and for originating IPv4 devices. In this process, the originating IP device determines the size of the
largest IPv6 or IPV4 packet that can be sent without being fragmented. The largest packet is equal to the
smallest MTU of any network between the IP source and the IP destination devices. If a packet is larger
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
IEEE 802.3ae 10 Gbps Ethernet
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