CCNP - CCIP

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Course Breakup

Frame-Relay & RIPv2 EIGRP, OSPF, Route Filtering & Redistribution OSPF & BGP MPLS & MPLS - VPN Advanced Switching & Security IOS Services & QOS Multicasting & IPv6 100 Point Super Lab

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BASIC SWITCHINGSection 2

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Basic Switching

Contents Simulating a logical topology with the physical topology VLAN VLAN Trunking VTP STP Ether-channel

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Basic Switching

Virtual LANs (VLANs) Virtual networking refers to the ability of switches and routers to

configure logical topologies on top of the physical network infrastructure

Virtual LANs (VLANs) offer significant benefits in terms of efficient use of bandwidth, flexibility, performance, and security

VLAN technology functions by logically segmenting the network into different broadcast domains so that packets are only switched between ports that are designated for the same VLAN

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Basic Switching

Trunking Overview A trunk is a point-to-point link between one or more Ethernet switch

interfaces and another networking device such as a router or a switch. Trunks carry the traffic of multiple VLANs over a single link.

Trunking encapsulations available on all Ethernet interfaces: Inter-Switch Link (ISL)-ISL is Cisco-proprietary trunking encapsulation. 802.1Q—802.1Q is industry-standard trunking encapsulation.

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Basic Switching

Default behavior of Switches Both 3550 and 3560 are L3 switches, i.e. with basic L2 switching

functionality and L3 routing functionality All interfaces by default are

3550 – Dynamic desirable 3560 – Dynamic auto

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Basic Switching

Native VLAN If a packet is received on a dot1q link, that does not have VLAN

tagged, it is assumed that it belongs to native VLAN If we change the native VLAN, then it has to match on both the

links Mismatch native VLANs can result in STP loops

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Basic Switching

Understanding VTP VTP is a Layer 2 protocol that maintains VLAN configuration

consistency by managing the addition, deletion, and renaming of VLANs on a network-wide basis

VTP minimizes misconfigurations and configuration inconsistencies that can cause several problems, such as duplicate VLAN names, incorrect VLAN-type specifications, and security violations

Before you create VLANs, you must decide whether to use VLAN Trunking Protocol (VTP) to maintain global VLAN configuration for your network

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Basic Switching

Understanding VTP (Cont’d) There are three different modes of VTP

Server Client Transparent

VTP works only on trunk links.

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Basic Switching

VTP Operation and Modes 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

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Basic Switching

VTP Pruning Increases available bandwidth by reducing unnecessary flooded

traffic Example: Station A sends broadcast, and broadcast is flooded

only toward any switch with ports assigned to the red VLAN

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Basic Switching

Version-dependant Transparent-mode VTP Version 2 supports token ring. In VTP Version 1, a VTP transparent switch inspects VTP

messages for the domain name and version and forwards message only if the version and domain name matches.

In VTP Version 2, a VTP transparent switch will not inspect VTP messages and forwards even it doesn’t match.

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Basic Switching

Ether Channel Used to aggregate bandwidth between multiple L2 / L3 interfaces “channel-group” command under the interface Port-channel is the logical instance of the physical interfaces The two Ether-channel protocols

PAgP (Port Aggregation Protocol) LACP (Link Aggregation Control Protocol)

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Basic Switching

Successful combination of etherchannel would be: On – On Desirable – Desirable Desirable – Auto Active – Active Active – Passive

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Mode Result

On PAgP and LACP disabled (negotiation disable)

Auto Passively listen for PAgP

Desirable Actively negotiate PAgP

Passive Passively listen for LACP

Active Actively negotiate LACP

Basic Switching

EtherChannel Modes  active Places an interface into an active negotiating state, in

which the interface starts negotiations with other interfaces by sending LACP packets

auto Places an interface into a passive negotiating state, in which the interface responds to PAgP packets it receives but does not start PAgP packet negotiation. This setting minimizes the transmission of PAgP packets

desirable Places an interface into an active negotiating state, in which the interface starts negotiations with other interfaces by sending PAgP packets

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Basic Switching

EtherChannel Modes  on Forces the interface into an EtherChannel without PAgP or

LACP. With the on mode, a usable EtherChannel exists only when an interface group in the on mode is connected to another interface group in the on mode

passive Places an interface into a passive negotiating state, in which the interface responds to LACP packets that it receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets

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Basic Switching

Layer 2 EtherChannels This example shows how to assign Gigabit Ethernet interfaces 0/4

and 0/5 as static-access ports in VLAN 10 to channel 5 with the PAgP mode desirable:

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Switch# configure terminal Switch(config)# interface range gigabitethernet0/4 -5 Switch(config-if-range)# switchport mode access Switch(config-if-range)# switchport access vlan 10 Switch(config-if-range)# channel-group 5 mode desirable

Basic Switching

Layer 3 EtherChannel

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Step1:-Switch# configure terminal Switch(config)# interface port-channel 5 Switch(config-if)# no switchport Switch(config-if)# ip address 172.10.20.10 255.255.255.0

Step2:-Switch(config)# interface range gigabitethernet0/1 -2 Switch(config-if-range)# no ip address Switch(config-if-range)# no switchport Switch(config-if-range)# channel-group 5 mode active

Basic Switching

Layer 2&3 EtherChannel You configure Layer 2 EtherChannels by configuring the Ethernet

interfaces with the channel-group interface configuration command, which creates the port-channel logical interface

When configuring Layer 3 EtherChannels, you must manually create the port-channel logical interface first by using the interface port-channel global configuration and then put the Ethernet interfaces into the port-channel

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Basic Switching

LACP EtherChannel When enabled, LACP tries to configure the maximum number of

LACP-compatible ports in a channel, up to a maximum of 16 ports. Only eight LACP links can be active at one time

PAGP support up to max 8 ports You can configure the system priority for all the EtherChannels

that are enabled for LACP by using the lacp system-priority global configuration command.

The switch with the lower priority will decide the logical link

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lacp system-priority priority (default priority is 32768)

Basic Switching

Configuring EtherChannel Load Balancing

#port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac

dst-ip—Load distribution is based on the destination-host IP address.

dst-mac—Load distribution is based on the destination-host MAC address of the incoming packet.

src-dst-ip—Load distribution is based on the source-and-destination host-IP address.

src-dst-mac—Load distribution is based on the source-and-destination host-MAC address.

src-ip—Load distribution is based on the source-host IP address. src-mac—Load distribution is based on the source-MAC address

of the incoming packet.

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THANK YOU

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