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SWITCH
A switch function at Layer 2 or Datalinklayer
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It uses Flooding and unicast for
communication
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BROADCAST DOMAIN
Broadcast is a type of communication, where the sending device send a data and
that copy of data will be delivered to every device in the network segment
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As the number of devices in the Broadcast Domain increases, number of
Broadcasts also increases and the quality of the network will come down
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In a "Shared Media" there are no
separate channels for sending and receiving the data signals, but only one
channel to send and receive the data signals
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MANAGEBLE SWITCHES
These typeof switches have one or more ways, or interfaces, to configure the
switch
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Changes that one can do from a
managed switch Examples of configuration include: enable features such as
Configuring IP address to switch, Spanning Tree Protocol, set port speed,create or
modify VLANs, etc
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They are basic
plug-and-play switches with no remote configuration, management, or
monitoring options
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CORE LAYER SWITCHES
The core layer devices is responsible for fast and reliable transportation
of data across a network in a quick manner
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It is used to speed up the network traffic as much as possible
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of interfaces
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EX:-6000, 5000, etc
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These type of devices have less no
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It also can forward heavy amount of traffic in a network
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EX:-4500, 3550, 3560 etc
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These devices used in a small network or in branch offices to connect
the end devices or users
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of interfaces
compare to Core or Distribution layer devices
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ARP (Address Resolution Protocol)
The address resolution protocol (ARP) is a protocol used by the Internet Protocol,
specifically IPv4, to map IP address to the hardware addresses used by a data link
protocol
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The term address
resolution refers to the process of finding an address of a Device in a network
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VLAN (Virtual Local Area Network)
VLAN is a logical segmentation of a switch
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The purpose of implementing a VLAN is to improve
the performance of a network
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In addition, VLANs are created to assist in issues like
security, network management and scalability
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In static VLAN switch port must
be manually assigned to a VLAN
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Port can be a member of only one VLAN
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DYNAMIC VLAN
In Dynamic VLAN devices are automatically assigned into VLAN based on its MAC
address
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An administrator can assign switch port to VLANs
dynamically based on information such as the MAC address of the device
connected to the port
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ETHERCHANNEL
Switch treats an Ether Channel as a single interface, thus
Eliminating the possibility of a switching loop
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If a single port
fails, traffic will be redirected to the other port(s)
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A maximum of 8 Fast Ethernet or 8 Gigabit Ethernet
ports can be grouped together when forming an Ether Channel
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The function of Spanning Tree Protocol (STP) is to prevent Layer 2
switching loop and broadcast storms in a Local Area Network (LAN) by shutting
down (or blocking) a port
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STP is enabled by default on all switches
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Ports in a blocking state do not
forward frames or learn MAC addresses
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LISTENING
A port will progress from a Blocking to a Listening state only if
the switch believes that the port will not beshut downto eliminate a loop
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Ports in a listening state will not
forward frames or learn MAC addresses
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Ports in a learning state listen for BPDUs, and also
begin to learn MAC addresses
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FORWARDING
A port in learning mode will be placed in forwarding mode
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All designated, root, and non-uplink ports will eventually be placed in a
forwarding state
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ROOT SWITCH OR BRIDGE
The first step in the STP process is electing a Root Bridge, which serves as the
centralized point of the STP topology
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The default priority is 32,768, and the lowest prioritywill elect as Root
Bridge
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The combination of a switch’s priority and MAC address make
up that switch’s Bridge ID
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NON ROOT SWITCH
In a Redundant switch network after electing ROOT SWITCH by STP
(Spanning Tree Protocol) rest of all the switches in a network is known as NON
ROOT SWITCH
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ROOT PORT
The root port is always the link connected to the rootbridge, or the shortest path
to the root bridge
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Lowest port cost will be selected as a root port
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DESIGNATED PORT
Each networksegmentrequires a single Designated Port, which has the lowest
path cost leading to the Root Bridge
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A port cannot be both a Designated Port and a Root Port
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NON DESIGNATED PORT OR BLOCKING PORT
The other end of a Designated Port is called as Non Designated Port (marked as
NDP), if it is NOT a Root Port
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RSTP (RAPID SPANNING TREE PROTOCOL)
The convergence time for legacy Spanning Tree Protocol (STP) IEEE
802
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When the network is converging on a
topology change, no traffic is forwarded to or from any of the switch
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RSTP is an open standard protocol
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1W standard is available to address the Spanning Tree Protocol
(STP) convergence time gap issue
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PVSTP (PER VLAN SPANNING TREE PROTOCOL)
Per-VLAN Spanning Tree (PVST) is a Cisco proprietary Spanning Tree Protocol
(STP) which operates a separate instance of Spanning Tree Protocol (STP) for each
individualVLAN
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Per-VLAN Spanning Tree (PVST) require Inter Switch Linktrunkingprotocol on the
ports
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Such a port is called a trunk port
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1Q tags) as they pass between switches, so
each frame can be routed to its intended VLAN
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It can carry only one VLAN information
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Switches remove
any VLAN information from the frame before it is sent to a device
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1Q
802
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802
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An untagged Ethernet frame is a
standard Ethernet frame
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If a switch receives untagged Ethernet frames on a trunk
port, they are considered as part of the native VLAN
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1Q
VLAN tagged Ethernet
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Both sides of the trunklink must be configured to be in same native VLAN
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But
configuring VLAN for large networks with many interconnected switches can be a
very difficult task
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The VLAN Trunking Protocol (VTP) can manage the addition, deletion, and
renaming of VLANs from a central point without manual intervention and thus
reduces network administration work in a switched network
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At least one server is required in a VTP domain to propagate VLAN
information within the VTP domain
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The changes made in a switch in server mode are advertised to the
entire VTP domain
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A network
switch in VTP client mode requires a server switch to inform it about the VLAN
changes
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VTP TRANSPARENT MODE
VLAN Trunking Protocol (VTP) transparent mode switches do not participate in
the VTP domain, but VTP transparent mode switches can receive and forward VTP
advertisements through the configured trunk links
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But it will not advertisement to any other switches in
the network
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Dynamic Trunking
Protocol (DTP) can be used negotiate and form trunk connection between Cisco
switches dynamically
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Bridge
Protocol Data Units (BPDUs) frames contain information regarding the Switch ID,
originating switch port, MAC address, switch port priority, switch port cost etc
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MAC ADDRESS TABLE
MAC Address table also known as CAM table (Content Addressable
Memory)
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The switch will build the table through a dynamic learning process, by
observing the source MAC address of frames
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A switch will only add MAC address table entries based on the
source MAC address in a frame
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It is used to
secure the switch port
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A user can also change his
physical location in LAN network
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Thus port security feature enhances
the LAN security
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While in this state, the switch port forwards no traffic
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RESTRICT VIOLATION
This violation permits traffic from known MAC addresses to continue to be
forwarded while dropping traffic from unknown MAC addresses when over the
allowed MAC address limit
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PROTECT VIOLATION
This violation permits traffic from known MAC addresses to continue to be
forwarded while dropping traffic from unknown MAC addresses when over the
allowed MAC address limit
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FHRP (FIRST HOP REDUNDENCY PROTOCOL)
First Hop Redundancy Protocol (FHRP) is a group of protocols that allow a
router on a LAN network to automatically take over if primary default gateway
router fails
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The problem comes when this primary router fails and there is a second
router on the segment that is also capable of being the default gateway but end
devices don’t know about it
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Solution to this problem is First Hop Redundancy
Protocols
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HSRP (HOT STANDBY ROUTER PROTOCOL)
HSRP is a Cisco proprietary protocol that provides default gateway
redundancy in LAN network
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With HSRP, a group of routers (gateways) will be
configured together, and a single HSRP virtual IP address is used by the devices on
the network
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Traffic always forward through ACTIVE ROUTER when ACTIVE ROUTER
fails STANDBY will take over for forwarding traffic
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Its operation is similar to HSRP but differs in a
couple of ways
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The master router's physical IP address of the
interface connecting the network is used by the clients as a default gateway
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GLBP offers
something that HSRP and VRRP does noti
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dynamic load balancing
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When
a GLBP is configured, one of the routers within the group will be elected as the
Active Virtual Gateway (AVG) and all remaining routers are in that group Active
Virtual Forwarder (AVF)
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to a switch port to avoid layer 2 switching loop
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