CCNA Routing and Switching Lesson 13 - Switching - Eric Vanderburg

1. Switching
Networking Essentials – Eric Vanderburg © 2005

2. Port Security
Switchport port security mac-address
mac-address
 Switchport port security mac-address
sticky – learn first MAC used and restrict
to that one


3. Switch modes
Store & forward – waits until entire frame
is analyzed to forward
 Fragment free – looks at first 64 bytes
before forwarding
 Cut through – forwards ASAP
 Adaptive cut through – acts like cut
through unless many errors are
encountered. If so, switches to store &
forward
 Switching-mode store-and-forward


4. STP
802.1d
 Used to reduce forwarding loops
 Allows redundancy without looping
 Elects root bridge based on lowest
bridge ID (MAC & priority)
 Root ports are put in forwarding state,
others in blocking
 Root switch enables all ports
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5. Other features
EtherChannel – allows multiple trunk
links to be used as one (2-8 links)
 PortFast – ports connected to hosts can
be enabled at once as soon as the first
frame is received


6. RSTP
802.1w
 Faster convergance
 PortFast & Etherchannel are both built-in
 Does not work when hubs are on the
network
 Can negotiate a new path to root
automatically without a link going down
first


7. VLANs
Segment into multiple broadcast
domains
 Requires layer 3 device to send data
between VLANs
 Requires trunking to move data to
VLANs spread between switches
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8. Trunking

ISL (Inter-Switch Link)
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IEEE 802.1q
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encapsulates
Default VLAN
Changes header
Trunk Types

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On
Off
Desirable
Auto

9. VTP
VTP allows configuration changes to be
propagated to other switches in the
same domain
 VTP modes

Server mode
 Client mode
 Transparent mode


VTP pruning – does not send VTP info to
a switch that has no ports in that VLAN

10. Switch commands

Interface fastethernet 0/0

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Duplex full / half / auto
Speed 10 / 100 / 1000 / auto
Spanning-tree cost cost – changes priority
Channel-group # - enables etherchannel
Show spanning-tree – view info on rootID,
bridgeID, & ports that are blocking or
forwarding
Show vtp status – shows number of VLANs,
operating mode for this device, & domain
name,

11. Trunking

interface fastethernet 0.1
encapsulation isl 1
 encapsulation dot1q 2 (do not set for main
interface because that will be default vlan)


12. VLAN comands

Vlan database

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SW1(vlan)#
Vlan 1 name Test
Vlan 2 name Sample
Vtp domain SampleDomain
Exit – must exit for changes to take place
Vtp pruning – turns pruning on in global config

Interface fastethernet 0/0



Switchport mode access – not trunk
Switchport access vlan 1
Interface range fastethernet 0/1 – 10

13. 1900 switch

Interface fastethernet 0/0
Vlan-membership static 2
 Exit


Set up vlans in configure terminal
instead of vlan database

14. Trunking commands

Interface fastethernet 0/0
Switchport mode dynamic desirable
 Switchport mode dynamic auto
 Switchport mode trunk
 Switchport mode access


Interface ethernet 0.2
Encapsulation isl vlan#
 Encapsulation dot1q vlan#
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