MAC address


A [MAC address](/mac-address) of all zeros is a special case MAC address.  It is used to refer to the localhost and corresponds with the 127.0.0.1 [localhost](/ipv4-internal-host-loopback-address-range) [IPv4](/ipv4) address.  

A MAC address of all zeros looks like the following:

00:00:00:00:00:00

It is also sued in [ARP](/arp) requests in the target hardware address field whenever this is unknown, but in such cases, the field is ignored.

## Links

https://forum.networklessons.com/t/how-does-a-switch-learn-mac-addresses/865/102?u=lagapides

https://www.reddit.com/r/techsupport/comments/emulwx/what_does_an_all_zeros_mac_address_mean/

https://en.wikipedia.org/wiki/Address_Resolution_Protocol#Packet_structure


MAC address of all zeros

IPv6

IS-IS - DIS and Pseudonode

IS-IS - Maximum composite metrics

IS-IS - attached bit

IS-IS - route filtering

IS-IS - up-down bit

IS-IS multitopology support

IS-IS

ISDN

ISIS circuit-type command

ISP Peering

ISPs, tiers, transiting, and the Internet

Importance of self-study for CCIE or CCDE

Interface - configuring a range of interfaces

Interface - no carrier counter

Interface - show interfaces counters explained

Interface - unknown protocol drops

Interface speed and bandwidth

Interior Gateway Protocol (IGP)

Internet Exchange Point (IXP)

Internet Service Provider (ISP)

Intrusion prevention system (IPS)

Kron task scheduler

L2TPv3 over IPSec

L2TPv3

LACP

LAG - Multi-Chassis LAG

LFA - Topology Independent LFA

LFA, remote LFA, and how they work together in OSPF

LISP - map request and reply process

LISP - what is it

LISP and overlapping address spaces

LISP debug traffic between two EIDs

LISP host mobility use cases

LISP where EID-to-RLOC mappings originate

LISP

Layer 2 network

Link State Routing Protocols

Linux - Line continuation character backslash

Local Proxy ARP

Loop-Free Alternate (LFA) Fast Reroute (FRR)

Loop-Free Alternate (LFA) and remote LFA

Loops in layers 2 and 3

MAC - changing the MAC address on a switchport

MAC Access List EtherType

MAC Access List

MAC Address Table - Static assignment use cases

MAC address flapping

MAC address table - Switches maintain one table per VLAN

MAC address table - multiple entries of the same MAC address

MAC address table - multiple static entries

MAC address table - show command on Nexus device

MAC address table - static entry

MAC address table populated using source address field

MAC address table static multicast entry

MAC address table

MPLS - BGP customer prefixes do not appear in the LFIB

MPLS - Connecting IPv6 sites over an IPv4 backbone

MPLS - Disabling IPv4 address family in BGP for VPNv4

MPLS - Ethernet over MPLS (EoMPLS)

MPLS - L3VPN BGP EIGRP redistribution

MPLS - L3VPN BGP OSPF Redistribution

MPLS - LDP source interface

MPLS - Layer 2 VPNs

MPLS - Multi-VRF CE

MPLS - OSPF redistributed routes appear as O IA

MPLS - Segment Routing over MPLS

MPLS - Transport Profile

MPLS - Using RSVP for Traffic Engineering

MPLS - Using the BGP Allow-AS in feature

MPLS - VPN label

MPLS - VPN redistributing default route from CE into BGP

MPLS - VPNv4 Labels are assigned per route

MPLS - Virtual Private Network (VPN)

MPLS - label distribution using MP-BGP

MPLS - label

MPLS - multiarea OSPF in the core

MPLS - network redundancy

MPLS - what is fate sharing

MPLS - what is seamless MPLS

MPLS 6PE uses two labels in the data plane

MPLS Bytes Label Switched in the LFIB

MPLS Customer Edge Router

MPLS L3 VPNs and the interaction between AS-Override and SoO

MPLS L3VPN Inter-AS Options

MPLS LDP Label Filtering

MPLS LDP Session Protection

MPLS LDP Targeted Hellos

MPLS LSR ID

MPLS Label Distribution Protocol

MPLS Label Distribution and Swapping

MPLS Label Edge Router

MPLS Label Switch Router

MPLS Layer 3 VPN communication between CE and PE routers

MPLS Layer 3 VPN communication between CE routers

MPLS Local Label Allocation Filtering

MPLS Penultimate hop popping

MAC address of all zeros

Links

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