Basic network training1

Global Technology Services, ASEAN
IBM Confidential | 2013
Basic Network Training
Thanaphum Bannasri
Salatas Padfusup

Global Technology Services
IBM ConfidentialBasic Network Training2
 DAY1
- Networking Fundamentals
- OSI 7 Layers
- IP Addressing / Subnetting
- Understanding Ethernet LAN
- Starting on Cisco Switch
- LAN Lab example
 DAY2
- Transport Protocol
- Starting on Cisco router
- Routing Fundamentals Static , RIP , OSPF , EIGRP
- Routing example
- Wireless LAN
Agenda

 DAY3
- Communication Cable Technologies
- Understanding Wan Technology
- Basic network command
- Basic network troubleshooting
Agenda

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Networking Fundamentals
Basic Network Training4

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Data Networks

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Network History

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Network Devices

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Network Topology

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Local-area Networks (LANs)

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Wide-area Networks (WANs)

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Metropolitan-Area Network (MANs)

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Storage-Area Networks (SANS)

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Virtual Private Networks (VPNs)

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Bandwidth

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OSI Model
Programmers
Do
Not
Throw
Sausage
Pizza
Away

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OSI Model

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OSI Layers

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OSI Layers
•Provides connectivity and path selection between two host
•Provides Logical address
•No error correction, best effort delivery.

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OSI Layers

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Peer-to-Peer Communication

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TCP/IP Model

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Encapsulation
Data
Segments
Packet
Frame
Bits
Data
Data

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IP Addressing

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IP Address
 An IP address has 32 bits divided into four octets
 To make the address easier to read, people use decimal numbers to
represent the binary digits
- Example: 192.168.1.1
 Dotted decimal notation
- When binary IP addresses are written in decimal format

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IP Packet

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IP Address

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IP Address Binary format

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MAC Address VS IP Address
 MAC address
- Identifies a specific NIC in a computer on a network
- Each MAC address is unique
- TCP/IP networks can use MAC addresses in communication
- Network devices cannot efficiently route traffic using MAC addresses because they:
• Are not grouped logically
• Cannot be modified
• Do not give information about physical or logical network configuration
 IP addressing
- Devised for use on large networks
- IP addresses have a hierarchical structure and do provide logical groupings
- IP address identifies both a network and a host

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IP Classes
 Class A
- Reserved for governments and large corporations throughout the world
- Each Class A address supports 16,777,214 hosts
 Class B
- Addresses are assigned to large- and medium-sized companies
- Each Class B address supports 65,534 hosts
• Class C
– Addresses are assigned to groups that do not meet the qualifications to obtain Class
A or B addresses
– Each Class C address supports 254 hosts
• Class D
– Addresses (also known as multicast addresses) are reserved for multicasting
– Multicasting is the sending of a stream of data (usually audio and video) to multiple
computers simultaneously
 Class E
- Addresses are reserved for research, testing, and experimentation
- The Class E range starts where Class D leaves off

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IP Address Classes
IP addresses are divided into classes to define the large,
medium, and small networks.
Class A addresses are assigned to larger networks.
Class B addresses are used for medium-sized networks,
Class C for small networks,
Class Dfor Multicasting
Class Efor Experimental purposes

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IP Classes

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Summary Address Classes

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IP address types
• IP address could be one of three categories
 Network address
 Host address
 Broadcast address

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Network / Broadcast Addresses
- Network address :
the first IP address in it which all host part bits = 0
- Broadcast address:
the last IP address in the network which all host part bits = 1
no. of host bits
- other addresses are host addresses = 2 - 2
- Here are some examples:
Class Network Address Broadcast Address
A 12.0.0.0 12.255.255.255
B 172.16.0.0 172.16.255.255
C 192.168.1.0 192.168.1.255

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Network Addressing
 IP addresses identify both the network and the host
- The division between the two is not specific to a certain number of octets
 Subnet mask
- Indicates how much of the IP address represents the network or subnet
 Standard (default) subnet masks:
- Class A subnet mask is 255.0.0.0
- Class B subnet mask is 255.255.0.0
- Class C subnet mask is 255.255.255.0

Subnet Mask
- 32 bit mask ( 1’s followed by 0’s )
- Used by routers and hosts to determine the number of
network- significant bits ( identified by 1’s )
and host- significant bits in an IP address (identified by 0’s)
- example :
Class Network Address Default subnet mask
A 12.0.0.0 255.0.0.0 or /8
B 172.16.0.0 255.255.0.0 or /16
C 192.168.0.0 255.255.255.0 or /24

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Octet Values of a Subnet Mask

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Network Addressing
 TCP/IP hosts use the combination of the IP address and the subnet mask
- To determine if other addresses are local or remote
- The binary AND operation is used to perform the calculation
 Subnetting
- Manipulation of the subnet mask to get more network numbers

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Network Addressing
0
0

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Subnetting
- Subnetting a network means to use the subnet mask to divide the
network and break a large network up into smaller, more efficient and
manageable segments, or subnets.
- Subnetting is done by taking part of host bits then add it to
the network part
Network part Host part
Subnet bits
Network part Host part
IP address

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Subnetting Example
Divide network 192.168.1.0/24 into 4 subnets
Solution: 4 subnets need 2 bits
192.168.1 . 0
192.168.1 . 0000 0000 to 0011 1111
192.168.1 . 0100 0000 to 0111 1111
192.168.1 . 1000 0000 to 1011 1111
192.168.1 . 1100 0000 to 1111 1111
subnet mask is 255.255.255.192 or /26
The first subnet is 192.168.1.0/26
The second subnet is 192.168.1.64/26
The third subnet is 192.168.1.128/26
The fourth subnet is 192.168.1.192/26
0 - 63
64 - 127
128 - 191
192 - 255

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Divide network 192.168.1.0/24 into 4 subnets
Solution :
- 4 subnets need 2 bits
- subnet mask = 255.255.255.192
- interesting octet is 192
- hop count = 256 – 192 = 64
- The first subnet is 192.168.1.0/26
- The second subnet is 192.168.1.64/26
- The third subnet is 192.168.1.128/26
- The fourth subnet is 192.168.1.192/26

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Determine if this IP is network address or host address or
broadcast address
172.16.5.0/23
Solution :
- subnet mask = 255.255.254.0
- interesting octet is 254
- hop count = 256 – 254 = 2
- The first subnet is 172.16.0.0/23
- The second subnet is 172.16.2.0/23
- The third subnet is 172.16.4.0/23
- The fourth subnet is 172.16.6.0/23
So 172.16.5.0/23 is a host address
172.16.5.0/23

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- Which IP address should be assigned to PC B ?
A . 192.168.5.5
B . 192.168.5.32
C . 192.168.5.40
D . 192.168.5.63
E . 192.168.5.75
192.168.5.33/27
?
A
B
Answer : C

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57
- Given the choices below, which address
represents a unicast address?
Answer : E
A . 224.1.5.2
B . FFFF. FFFF. FFFF.
C . 192.168.24.59/30
D . 255.255.255.255
E . 172.31.128.255/18

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IPv4 VS IPv6
 IP version 4 (IPv4)
- The version of IP currently deployed on most systems today
 IP version 6 (IPv6)
- Originally designed to address the eventual depletion of IPv4 addresses
 CIDR has slowed the exhaustion of IPv4 address space and made the move
to IPv6 less urgent
- However, CIDR is destined to become obsolete because it is based on IPv4
 Network address translation (NAT)
- Another technique developed in part to slow the depletion of IPv4 addresses
- Allows a single IP address to provide connectivity for many hosts
 NAT is CPU intensive and expensive
- Some protocols do not work well with NAT, such as the IP Security Protocol (IPSec)
 IPv4 does not provide security in itself
- Has led to security issues with DNS and ARP

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IPv4 VS IPv6
 Security concerns were factored into the design of IPv6
 IPv4 networks rely on broadcasting
- Inefficient because many hosts unnecessarily see and partially process traffic not
ultimately destined for them
 IPv6 does away completely with broadcasting and replaces it with multicasting
 IPv6 addresses are 128 bits compared with IPv4’s 32-bit structure
 IPv6 addresses are expressed as hexadecimal numbers
- Example: 3FFE:0501:0008:0000:0260:97FF:FE40:EFAB
 IPv6 can be subnetted
- CIDR notation is also used with IPv6
• Example: 2001:702:21:: /48
 Organizations requesting an IPv6 address may be assigned a /64 prefix
- Minimum subnet with space for over a billion hosts

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Transitioning to IPv6
 Dual stack
- Involves enabling IPv6 on all routers, switches, and end nodes but not disabling
IPv4
- Both version 4 and version 6 stacks run at the same time
 Tunneling
- Encapsulates IPv6 traffic inside IPv4 packets
- Done when portions of a network are running IPv6 and other network areas have not
been upgraded yet
- Greatest concern: security

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Getting an Interface Address from a DHCP Server
• No manual IP address is configured on the interface.
• The router operates as a DHCP client.
• The ISP provides DHCP information.

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UNDERSTANDING ETHERNET LAN

IBM ConfidentialEssential Switch Command Training67

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Function of LAN
• Data and applications
• Share resources
• Provide communication path to other networks

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Fiber-Optic GBIC SFP

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STARTING ON CISCO SWITCH

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Catalyst 2960 LED Indicators
1 SYST LED 5 Speed LED
2 RPS LED 6 PoE LED1
3 Status LED 7 Mode button
4 Duplex LED 8 Port LEDs

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VLAN, Trunking, VTPVLAN, Trunking, VTP

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VLAN
• VLAN introduction
• LAN VS. VLAN
• Two Subnets, One Switch, No VLANs
• Traditional Solution: Multiple Switches
• Broadcast domains with VLANs
• VLAN Operation
• Configuration
• LAB

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VLAN introduction
vlan
10
Default
vlan 1
Default
vlan 1
• VLANs provide segmentation based on broadcast domains.
• VLAN = Subnet
• VLANs can logically segment switched networks based on:
 Physical location (Example: Building)
 Organization (Example: Marketing)
 Function (Example: Staff)

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• VLANs are created to provide segmentation services traditionally
provided by physical routers in LAN configurations.
• VLANs address scalability, security, and network management.
Without
VLANs
10.3.0.0/16
10.2.0.0/16
10.1.0.0/16
One link per VLAN or a single VLAN
Trunk (later)
With
VLANs
10.1.0.0/16
10.2.0.0/16
10.3.0.0/16
VLAN introduction

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LAN VS. VLAN

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Two Subnets, One Switch, No VLANs
• Layer 2 Broadcasts
 What happens when 10.1.0.10 sends an ARP Request for
10.1.0.30?
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1

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• Layer 2 Broadcasts
 Switch floods it out all ports.
 All hosts receive broadcast, even those on a different subnet.
 Layer 2 broadcast should be isolated to only that network.
 Note: If the switch supports VLANs, by default all ports belong to
the same VLAN and it floods it out all ports that belong to the same
VLAN as the incoming port (coming).
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1

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• Layer 2 Unknown Unicasts
 This is the same for unknown unicasts.
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1

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Traditional Solution: Multiple Switches
• The traditional solution is have devices on the same subnet connected
to the same switch.
• This provides broadcast and unknown unicast segmentation, but is
also less scalable.
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1
Fa 0/0 Fa 0/1
10.1.0.1/16 10.2.0.1/16
ARP Request

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Broadcast domains with VLANs
• A VLAN is a broadcast domain created by one or more switches.
• VLANs are assigned on the switch and correspond with the host IP
address.
• Each switch port can be assigned to a different VLAN.
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1
Port 1 VLAN
10
Port 9 VLAN
10
Port 12
VLAN 20
Port 4 VLAN
20

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Broadcast domains with VLANs
• Ports assigned to the same VLAN share the same broadcast domain.
• Ports in different VLANs do not share the same broadcast domain.
10.1.0.10/16
DG: 10.1.0.1
10.2.0.20/16
DG: 10.2.0.1
10.1.0.30/16
DG: 10.1.0.1
10.2.0.40/16
DG: 10.2.0.1
Port 1 VLAN
10
Port 9 VLAN
10
Port 12
VLAN 20
Port 4 VLAN
20
ARP Request

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VLAN Operation

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Configuration : Static VLANSConfiguration : Static VLANS
• Static membership VLANs are called port-based and port-centric
membership VLANs.
• This is the most common method of assigning ports to VLANs.
• As a device enters the network, it automatically assumes the VLAN
membership of the port to which it is attached.
• There is a default VLAN, on Cisco switches that is VLAN 1.
VLAN 10
Configured
Default
VLAN 1
Default
VLAN 1
Switch(config)#interface fastethernet 0/9
Switch(config-if)#switchport access vlan 10

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Configuration : Ranges of VLANsConfiguration : Ranges of VLANs
• This command does not work on all 2900 switches, such as the 2900
Series XL.
• This format of this command may vary somewhat on various 2900
switches.
vlan 3
Switch(config)#interface range fastethernet 0/8 - 12
Switch(config-if)#switchport access vlan 3
Switch(config-if)#switchport mode access
Switch(config-if)#exit

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Configuration : Verifying VLANs – show vlanConfiguration : Verifying VLANs – show vlan

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Configuration : Verifying VLANs – show vlan briefConfiguration : Verifying VLANs – show vlan brief

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Configuration : Deleting VLANsConfiguration : Deleting VLANs
Switch(config-if)#no switchport access vlan vlan_number
• This command will reset the interface to VLAN 1.
• VLAN 1 cannot be removed from the switch.

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LAB1LAB1
Test Ping
192.168.0.1/24 192.168.0.2/24
Port 1-3
VLAN 10
192.168.0.3/24
User1 User2 User3
User1
User2 User3
Port 4-6
VLAN 10
Port 7-9
VLAN 20

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LAB2LAB2
Test Ping
192.168.0.1/24 192.168.0.2/24
Port 1-3
VLAN 10
192.168.0.3/24
User1 User2 User3
User1
User2 User3
Port 4-6
VLAN 20
Port 7-9
VLAN 20

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Trunking
• VLAN Operation (No Trunking)
• VLAN Operation (Trunking)
• Trunking/Tagging
• 802.1Q Tagging (Standard)
• ISL Tagging (Cisco Proprietary)
• Trunking operation
• Trunking Applied
• Configuration
• LAB

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VLAN Operation (No Trunking)
• Can VLANs span across multiple switches?
•Which VLAN can?
•Which VLAN can not?
• What is Benefit of Trunking?
1 2 3 1 2 3

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VLAN Operation (Trunking)
• Each logical VLAN is like a separate physical bridge.
• VLANs can span across multiple switches.
• Trunks carry traffic for multiple VLANs.
• Trunks use special encapsulation to distinguish between
different VLANs.
1 2 3 1 2 3

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Trunking / Tagging
• VLAN Tagging is used when a single link needs to carry traffic for
more than one VLAN.
No VLAN Tagging
VLAN Tagging

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Trunking / Tagging
• There are two major methods of frame tagging, Cisco proprietary Inter-Switch Link (ISL) and IEEE
802.1Q.
• ISL used to be the most common, but is now being replaced by 802.1Q frame tagging. ISL
Increases the frame header overhead by 30 bytes.
• Cisco recommends using 802.1Q. This type of encapsulation adds only 4 bytes to the Ethernet
header

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802.1Q Tagging (Standard)

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ISL Tagging (Cisco Proprietary)

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Trunking Applied

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Configuration : TrunkingConfiguration : Trunking
• These commands will be explained in the following slides.
Note: On many
switches, the
switchport trunk
encapsulation
command must be
done BEFORE the
switchport mode
trunk command.

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• This command configures VLAN tagging on an interface if the switch
supports multiple trunking protocols.
• The two options are:
– dot1q – IEEE 802.1Q
– isl – ISL
• The tagging must be the same on both ends.
Switch (config-if)#switchport trunk encapsulation [dot1q|isl]

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An access port means that the port (interface) can only belong to a single
VLAN.
• Access ports are used when:
– Only a single device is connected to the port
– Multiple devices (hub) are connected to the port, all belonging to
the same VLAN
– Another switch is connected to this interface, but this link is only
carrying a single VLAN (non-trunk link).
• Trunk ports are used when:
– Another switch is connected to this interface, and this link is
carrying multiple VLANa (trunk link).
Switch(config-if) #switchport mode [access|trunk]

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LAB1LAB1
192.168.10.1/24 192.168.20.1/24
Port 1-3
VLAN 10
192.168.30.1/24
Group 1 Group 2
User1 User2 User3
Trunk
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 1-3
VLAN 10
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 10-12
Trunk
192.168.10.2/24 192.168.20.2/24 192.168.30.2/24
User1 User2 User3
Allow
All VLAN
Port 10-12
Trunk
Allow
All VLAN

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LAB2LAB2
192.168.10.1/24 192.168.20.1/24
Port 1-3
VLAN 10
192.168.30.1/24
Group 1 Group 2
User1 User2 User3
Trunk
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 1-3
VLAN 10
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 10-12
Trunk
192.168.10.2/24 192.168.20.2/24 192.168.30.2/24
User1 User2 User3
Allow
VLAN
10&20
Port 10-12
Trunk
Allow
VLAN
10&20

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LAB3LAB3
192.168.10.1/24 192.168.20.1/24
Port 1-3
VLAN 10
192.168.30.1/24
Group 1 Group 2
User1 User2 User3
Trunk
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 1-3
VLAN 10
Port 4-6
VLAN 20
Port 7-9
VLAN 30
Port 10-12
Trunk
192.168.10.2/24 192.168.20.2/24 192.168.30.2/24
User1 User2 User3
Allow
VLAN
10&30
Port 10-12
Trunk
Allow
VLAN
20&30

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VLAN Trunking Protocol (VTP)
• VLAN Management Challenge
• What is VTP?
• VTP Overview
• Benefits of VTP
• VTP Mode
• VTP Operation
• Three types of VTP messages
• VTP Configuration
• Verifying VTP
• Adding a switch to an existing VTP domain
• LAB

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VLAN Management Challenge
It is not difficult to add new VLAN for a small network

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VLAN Management Challenge
It is not easy to add a new VLAN to all of switches

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What is VTP?
 VTP allows a network manager to configure a switch so that it will
propagate VLAN configurations to other switches in the network.
 The switch can be configured in the role of a VTP server or a VTP
client.
 VTP only learns about normal-range VLANs (VLAN IDs 1 to 1005).
 Extended-range VLANs (IDs greater than 1005) are not supported
by VTP.

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VTP Overview
 VTP allows a network manager to makes changes on a switch that
is configured as a VTP server.
 Basically, the VTP server distributes and synchronizes VLAN
information to VTP-enabled switches throughout the switched
network, which minimizes the problems caused by incorrect
configurations and configuration inconsistencies.
 VTP stores VLAN configurations in the VLAN database called
vlan.dat.

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• Forwards
advertisements
• Synchronizes
• Not saved in
NVRAM
• Creates VLANs
• Modifies VLANs
• Deletes VLANs
• Sends/forwards
advertisements
• Synchronizes
• Saved in NVRAM
• Creates VLANs
• Modifies VLANs
• Deletes VLANs
• Forwards
advertisements
• Does not
synchronize
• Saved in NVRAM
VTP Modes

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• VTP advertisements are sent as multicast frames.
• VTP servers and clients are synchronized to the latest revision number.
• VTP advertisements are sent every 5 minutes or when there is a change.
VTP Operation

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Three types of VTP messages
• By default, server and client Catalyst switches issue summary
advertisements every five minutes.

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Configuration : Domain and PasswordConfiguration : Domain and Password
• The domain name can be between 1 and 32 characters.
• The optional password must be between 8 and 64 characters long.
• If the switch being installed is the first switch in the network, the
management domain will need to be created.
• However, if the network has other switches running VTP, then the new
switch will join an existing management domain.
• Caution: The domain name and password are case sensitive.

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Configuration : (Secure Mode)Configuration : (Secure Mode)
• By default, management domains are set to a nonsecure mode,
meaning that the switches interact without using a password.
• Adding a password automatically sets the management domain to
secure mode.
• The same password must be configured on every switch in the
management domain to use secure mode.

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Configuration : VTP modeConfiguration : VTP mode
Switch#config terminal
Switch(config)#vtp mode [client|server|transparent]
Switch#vlan database
Switch(vlan)#vtp [client|server|transparent]

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Configuration : Creating VLANsConfiguration : Creating VLANs
Create the VLAN:
Switch(vlan)#vlan vlan_number
Switch(vlan)#name vlan_name
Switch(vlan)#exit
Configuration : Delete the VLAN From DatabaseConfiguration : Delete the VLAN From Database
Create the VLAN:
Switch(vlan)#no vlan vlan_number
Switch(vlan)#exit

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Configuration : VerifyingConfiguration : Verifying
• This command is used to display statistics about advertisements sent
and received on the switch.

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Configuration : Erasing VLAN informationConfiguration : Erasing VLAN information
• VLAN information is kept in the vlan.dat file.
• The file is not erased when erasing the startup-config.
• To remove all VLAN information, use the command above and reload
the switch.
Switch#delete flash:vlan.dat
Delete filename [vlan.dat]?
Delete flash:vlan.dat? [confirm]
Switch#erase startup-config
Switch#reload

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Configuration : Adding a switch to an existing VTP domainConfiguration : Adding a switch to an existing VTP domain
• Use caution when inserting a new switch into an existing domain.
• In order to prepare a switch to enter an existing VTP domain, perform
the following steps.
• Delete the VLAN database, erase the startup configuration, and power
cycle the switch.
• This will avoid potential problems resulting from residual VLAN
configurations or adding a switch with a higher VTP configuration
revision number that could result in the propagation of incorrect VLAN
information.
• From the privileged mode, issue the delete vlan.dat and erase startup-
config commands, then power cycle the switch.

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LAB1LAB1
Group 1 Group 2
Port 10
Trunk
Port 10
Trunk
Switch1 Switch2
VTP Mode : Server
VTP Domain Name : Basicnetwork
VTP Password : Basicnetwork
VLAN :
VLAN 10 Name V10
VLAN 20 Name V20
VTP Mode : Client

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Spanning-Tree

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• Provides a loop-free redundant network topology by
placing certain ports in the blocking state.
Spanning -Tree ProtocolSpanning -Tree Protocol

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• One root bridge per network
• One root port per nonroot bridge
• One designated port per segment
• Nondesignated ports are unused
Spanning -Tree OperationSpanning -Tree Operation

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• Bpdu = Bridge Protocol Data Unit
(default = sent every two seconds)
• Root bridge = Bridge with the lowest bridge ID
• Bridge ID =
• In the example, which switch has the lowest bridge ID?
Spanning -Tree Root Bridge SelectionSpanning -Tree Root Bridge Selection

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• Spanning-tree transits each port through several different states:
Spanning -Tree Port StatesSpanning -Tree Port States

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Spanning -Tree Port States (Cont.)Spanning -Tree Port States (Cont.)

IBM Confidential
Spanning – Tree Path CostSpanning – Tree Path Cost

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Spanning – Tree ExampleSpanning – Tree Example

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Spanning – Tree RecalculationSpanning – Tree Recalculation

IBM Confidential
• Convergence occurs when all the switch and bridge
ports have transitioned to either the forwarding or
the blocking state.
• When the network topology changes, switches and
bridges must recomputed the Spanning-Tree
Protocol, which disrupts user traffic.
Spanning – Tree ConvergenceSpanning – Tree Convergence

IBM Confidential
Switch#show spanning-tree vlan 1
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0001.96DC.1A62
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32770 sys-id-ext 1)
Address 0010.1116.A3A4
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.3 Shr
Fa0/2 Root FWD 19 128.3 Shr
Switch(config)#spanning-tree vlan 1 priority 4096
Spanning – Tree StatusSpanning – Tree Status

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Aggregation Switch Links

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EtherChannel Overview
• EtherChannel bundles individual Ethernet links into a single logical link
that provides bandwidth up to 1600 Mbps (8 links of Fast Ethernet), 16
Gbps (8 links of Gigabit Ethernet), or 160 Gbps (8 links of 10-Gigabit
Ethernet).
• A Catalyst 4500 series and 2960G switch supports a maximum of 64
EtherChannels. You can form an EtherChannel with up to eight
compatibly configured Ethernet interfaces. All interfaces in each
EtherChannel must be the same speed and must be configured as
either Layer 2 or Layer 3 interfaces.

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EtherChannel Overview
• If one of the links within the bundle fails, traffic sent through that link
automatically is moved to an adjacent link.
• Failover occurs in less than a few milliseconds and is transparent to
the end user.
• As more links fail, more traffic is moved to further adjacent links.
Likewise, as links are restored, the load automatically is redistributed
among the active links

IBM Confidential
Bundling Ports with EtherChannel
Generally, all bundled ports first must belong to the same VLAN. If
used as a trunk, bundled ports must be in trunking mode, have the
same native VLAN, and pass the same set of VLANs. Each of the
ports should have the same speed and duplex settings before being
bundled.

IBM Confidential
Distributing Traffic in EtherChannel
The algorithm can use source IP address, destination IP address, or a
combination of source and destination IP addresses, source and
destination MAC addresses, or TCP/UDP port numbers. The hash
algorithm computes a binary pattern that selects a link number in the
bundle to carry each frame.
If only one address or port number is hashed, a switch forwards each
frame by using one or more low-order bits of the hash value as an
index into the bundled links. If two addresses or port numbers are
hashed, a switch performs an exclusive-OR (XOR) operation on one or
more loworder bits of the addresses or TCP/UDP port numbers as an
index into the bundled links.

IBM Confidential
Distributing Traffic in EtherChannel
Sample address bits are shown. The XOR operation produces a 0 bit if
the two input bits are the same (0,0 or 1,1) and a 1 bit if the two input
bits are different (0,1 or 1,0).

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EtherChannel Load Balancing
The hashing operation can be performed on either MAC or IP
addresses and can be based solely on source or destination
addresses, or both. Use the following command to configure frame
distribution for all EtherChannel switch links:
Switch(config)# port-channel load-balance method

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EtherChannel Negotiation Protocols
EtherChannels can be negotiated between two switches to provide
some dynamic link configuration. Two protocols are available to
negotiate bundled links in Catalyst switches. The Port Aggregation
Protocol (PAgP) is a Cisco-proprietary solution, and the Link Aggregation
Control Protocol (LACP) is standards based.

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As ports are configured to be members of an EtherChannel, the switch
automatically creates a logical port-channel interface. This interface
represents the channel as a whole.
Configuration : EtherChannel ConfigurationConfiguration : EtherChannel Configuration

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First, verify the EtherChannel state with the show etherchannel
summary command. Each port in the channel is shown, along with
flags indicating the port’s state
Troubleshooting : EtherChannelTroubleshooting : EtherChannel

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You can verify the channel
negotiation mode with the
show etherchannel port
command, The local switch is
shown using desirable mode
with PAgP (Desirable-Sl is
desirable silent mode).
Notice that you also can see
the far end’s negotiation
mode under the Partner
Flags heading, as A, or auto
mode.

IBM Confidential

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