Unicast traffic

Tags #unknown_unicast #unicast 

Unknown unicast traffic is [Unicast traffic](/unicast-traffic) for which the [switches](/switching) in the network have not yet learned the port to which the destination [MAC address](/mac-address) belongs.  When the destination MAC address is not found within the [MAC address table](/mac-address-table) of a switch, such a frame is sent out of all ports of the switch except the one on which the frame arrived.  

Once the destination device responds, its MAC address is recorded in the MAC address table, and any traffic destined to that device is no longer considered unknown unicast, but simply unicast.

Links:

https://www.cisco.com/en/US/docs/general/Test/dwerblo/broken_guide/blocking.html#wp1035969

Unknown unicast traffic

Switching - store and forward

Switching - switch fabric

Switching - switched virtual interface (SVI)

Switching - switchport autostate command

Switching

Switchport - IEEE 802.1q

Switchport - ISL

Switchport access

Switchport modes

Switchport trunk configuration ignores access commands

Switchport trunk encapsulation

Switchport trunk

Symmetric Digital Subscriber Line (SDSL)

Syslog - terminal monitor

Syslog relay or proxy

Syslog severity levels

TCP - Congestion control

TCP - Header

TCP - SEQ and ACK values

TCP - Slow start

TCP - Three-way handshake

TCP - Urgent pointer field

TCP - Window Size Scaling

TCP - factors affecting segment size

TCP - role of checksum field

TCP MSS and window size

TCP RST flag

TCP SYN timeout

TCP header options

TCP phantom byte

TCP-IP model

TFTP

Tcl Shell

Telnet

Time to live

Traceroute - Interpreting output

Traceroute asterisk and !H responses

Traceroute

Transparent Cisco IOS Firewall use cases

Transport Layer port number

Troubleshooting - using Telnet to test transport layer ports

Troubleshooting a slow network

Troubleshooting high CPU and memory usage on a switch

UDP - Header

UDP - Maximum Datagram Size

Unicast Reverse Path Forwarding (uRPF)

Upgrade your R&S skills to modern networking

VACL - Changes to ACL are active immediately

VLAN - Extended Range

VLAN - Native VLAN best practices

VLAN - Native VLAN on a router on a stick

VLAN - Private VLAN

VLAN - VLAN IDs 0 and 4095

VLAN Access Lists

VLAN Mapping

VLAN SVI status

VLAN Tag

VLAN control frames

VLAN

VLANs - 802.1Q tunneling (QinQ)

VLANs - Dynamic VLAN membership (VMPS)

VLANs - QinQ and CDP

VLANs - Vlans allowed and active in management domain

VLANs - when a tagged frame arrives on an access port

VLANs SVI

VPN - IKEv2 peer address of 0.0.0.0 0.0.0.0

VPN - crypto keepalive

VPN - default gateway for site to site VPN

VPN - default gateway of VPN client

VPN - split tunneling

VPN DVTI tunnel source

VRF - Definition mode

VRF - VPNv4 address

VRF capability vrf-lite command

VRF lite route leaking

VRF sharing across multiple routers

VRF use cases

VRRP - Virtual IP doesn't respond to pings

VRRP - load balancing

VRRP - support for authentication

VRRP - using the same ID on different interfaces

VRRP - using the same ID on subinterfaces

VRRP on sub-interfaces

VTP - Client can't modify VLANs

VTP - Multiple Servers with VTP version 2

VTP - Per interface configuration

VTP - Revision Numbers on transparent switch

VTP - Versions

VTP - domain name automatically changes

VTP - employing in an emulator

VTP - protecting switches from lower revision numbers

VTP Advertisements

VTP configuration checklist

VTP filtering shared VLANs

Unknown unicast traffic

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