CCNA Revised

Things are definitely afoot in the Cisco certification world, and with the economy in its current state of affairs, it is more important now than ever to attain your certification. Here we’ll demystify a couple of the Cisco certifications and help lay out a path to success.

CCNA and CCNP Certification
The Cisco Certified Network Associate (CCNA) certification is at the apprentice level of the networking profession. This can be misleading and is discussed in more detail later in this article. There is only one exam required for the CCNA level. The newest exam for CCNA is:

• #640-607 CCNA: Cisco Certified Network Associate

The Cisco Certified Network Professional (CCNP) is considered a journeyman level of skill, well above and beyond the CCNA level, and requires you to pass four more exams after the CCNA. Those exams may be taken in any order and are as follows:

• #640-604 BCMSN: Building Cisco Multilayer Switched Networks
• #640-901 BSCI: Building Scalable Cisco Internetworks
• #640-605 BCRAN: Building Cisco Remote Access Networks
• #640-606 CIT: Cisco Internetwork Troubleshooting

However, there is a shorter path to CCNP, requiring only two exam

Frame Relay is a high-performance WAN protocol that operates at the physical and data link layers of the OSI reference model. Frame Relay originally was designed for use across Integrated Services Digital Network (ISDN) interfaces. Today, it is used over a variety of other network interfaces as well. This chapter focuses on Frame Relay's specifications and applications in the context of WAN services.

Frame Relay is an example of a packet-switched technology. Packet-switched networks enable end stations to dynamically share the network medium and the available bandwidth. The following two techniques are used in packet-switching technology:

•Variable-length packets

•Statistical multiplexing

Frame Relay Devices

Devices attached to a Frame Relay WAN fall into the following two general categories:

•Data terminal equipment (DTE)

•Data circuit-terminating equipment (DCE)

Frame Relay Example Configuration

service udp-small-servers
service tcp-small-servers
!
hostname Atlanta
!
enable secret cisco
!
ip subnet-zero
ip domain-lookup
ip name-server 129.250.35.250 129.250.35.251
!
interface Ethernet0
ip address 209.39.6.1 255.255.255.0
!
interface Serial0
no ip address
encapsulation frame-relay
frame-relay lmi-type ansi
!
interface Serial0.16 point-to-point
description Frame Relay to Boston
ip address 199.1.138.2 255.255.255.252
frame-relay interface-dlci 16
!
ip http server
ip classless
ip route 0.0.0.0 0.0.0.0 serial0.16
!
line con 0
password console
login
line aux 0
line vty 0 4
password telnet
login
!

DTEs generally are considered to be terminating equipment for a specific network and typically are located on the premises of a customer. In fact, they may be owned by the customer. Examples of DTE devices are terminals, personal computers, routers, and bridges.

DCEs are carrier-owned internetworking devices. The purpose of DCE equipment is to provide clocking and switching services in a network, which are the devices that actually transmit data through the WAN. In most cases, these are packet switches. Figure 10-1 shows the relationship between the two categories of devices.

Figure 10-1 DCEs Generally Reside Within Carrier-Operated WANs

The connection between a DTE device and a DCE device consists of both a physical layer component and a link layer component. The physical component defines the mechanical, electrical, functional, and procedural specifications for the connection between the devices. One of the most commonly used physical layer interface specifications is the recommended standard (RS)-232 specification. The link layer component defines the protocol that establishes the connection between the DTE device, such as a router, and the DCE device, such as a switch. This chapter examines a commonly utilized protocol specification used in WAN networking: the Frame Relay protocol.

Frame Relay Virtual Circuits

Frame Relay provides connection-oriented data link layer communication. This means that a defined communication exists between each pair of devices and that these connections are associated with a connection identifier. This service is implemented by using a Frame Relay virtual circuit, which is a logical connection created between two data terminal equipment (DTE) devices across a Frame Relay packet-switched network (PSN).

Virtual circuits provide a bidirectional communication path from one DTE device to another and are uniquely identified by a data-link connection identifier (DLCI). A number of virtual circuits can be multiplexed into a single physical circuit for transmission across the network. This capability often can reduce the equipment and network complexity required to connect multiple DTE devices.

A virtual circuit can pass through any number of intermediate DCE devices (switches) located within the Frame Relay PSN.

Frame Relay virtual circuits fall into two categories: switched virtual circuits (SVCs) and permanent virtual circuits (PVCs).

Switched Virtual Circuits

Switched virtual circuits (SVCs) are temporary connections used in situations requiring only sporadic data transfer between DTE devices across the Frame Relay network. A communication session across an SVC consists of the following four operational states:

•Call setup—The virtual circuit between two Frame Relay DTE devices is established.

•Data transfer—Data is transmitted between the DTE devices over the virtual circuit.

•Idle—The connection between DTE devices is still active, but no data is transferred. If an SVC remains in an idle state for a defined period of time, the call can be terminated.

•Call termination—The virtual circuit between DTE devices is terminated.

After the virtual circuit is terminated, the DTE devices must establish a new SVC if there is additional data to be exchanged. It is expected that SVCs will be established, maintained, and terminated using the same signaling protocols used in ISDN.

Few manufacturers of Frame Relay DCE equipment support switched virtual circuit connections. Therefore, their actual deployment is minimal in today's Frame Relay networks.

Previously not widely supported by Frame Relay equipment, SVCs are now the norm

Configuring VLANs

Before you begin creating VLANs, you should determine whether the switch will participate in a VTP domain that will synchronize VLAN configuration with the rest of the network. You must also enable a trunk connection if you want to use VLANs across multiple switches.The steps to configure a VLAN are:
Enable VTP (optional)
Enable Trunking (optional)
Create VLANs
Assign VLANs to ports Verifying VLANs
Verifying the VLAN Configuration
Verifying VLAN Membership
Prevent VLANs from Crossing a Trunk Link
Prevent Individual VLANs from Crossing a Trunk Link
Verifying Trunk Links
Verifying VTP Information
Enabling VTP Pruning Enable VTP
When adding a new switch to an existing domain, it is a good idea to add it in VTP client mode. This will prevent the switch from propagating any incorrect VLAN information to other switches. In this example we will setup a new VTP domain and place the switch into server mode. The password puts VTP into secure mode. Every switch in the management domain must have a password assigned to it for the management domain to function properly in secure mode. Switch1#configure terminalEnter configuration commands, one per line. End with CNTL/ZSwitch1(config)#vtp serverSwitch1(config)#vtp domain ciscotestSwitch1(config)#vtp password ccnaEnable Trunking
The next step is to create a trunk connection with the other switches that will be sharing VLAN information. To enable trunking on a port, enter interface configuration mode for the desired port, and then use the trunk command with the appropriate option: Switch1#configure terminalSwitch1(config)#interface f 0/26Switch1(config-if)#trunk on
trunk Command Options
Option
Function
on
Puts the port into permanent trunking mode and negotiates to convert the link into a trunk link. The port becomes a trunk port even if the neighboring port does not agree to the change.
off
Puts the port into permanent nontrunking mode and negotiates to convert the link into a nontrunk link. The port becomes a nontrunk port even if the neighboring port does not agree to the change.
desirable
Makes the port actively attempt to convert the link to a trunk link. The port becomes a trunk port if the neighboring port is set to on, desirable, or auto mode.
auto
Makes the port willing to convert the link to a trunk link. The port becomes a trunk port if the neighboring port is set to on or desirable mode. This is the default mode.
negotiate
Puts the port into permanent trunking mode but prevents the port from generating DTP frames. You must configure the neighboring port manually as a trunk port to establish a trunk link.Create VLANs
To create a VLAN, enter global configuration mode and use the vlan command with the VLAN identifier (1-1005) and its name. Switch1#configure terminalSwitch1(config)#vlan 5 name accountingSwitch1(config)#vlan 6 name management Assign VLANs to Ports
Now that the VLAN has been created, you can statically assign which ports will be members of the VLAN. A port can only belong to one VLAN at a time and by default, all ports are members of VLAN 1. To assign a VLAN to a port, enter interface configuration mode for the port and use the vlan-membership command. Switch1#configure terminalSwitch1(config)#interface e0/4Switch1(config-if)#vlan-membership static 5Switch1(config)#interface e0/5Switch1(config-if)#vlan-membership static 5Switch1(config)#interface e0/6Switch1(config-if)#vlan-membership static 6Verifying the VLAN Configuration
To view the VLANs configured on the switch, use the show vlan command. Switch1#show vlanVLAN Name Status Ports--------------------------------------------------1 default Enabled 1-3, 7-24, AUI, A, B5 accounting Enabled 4, 56 management Enabled 6
Optionally you can view an individual VLAN to see how it's configured by using the show vlan [#] command.Switch1#show vlan 5VLAN Name Status Ports-------------------------------------5 accounting Enabled 2-------------------------------------VLAN Type SAID MTU Parent RingNo BridgeNo Stp Trans1 Trans2---------------------------------------------------------------------5 Ethernet 100005 1500 0 1 1 Unkn 0 0Verifying VLAN Membership
To view which ports are assigned to a VLAN, use the following command: Switch1#show vlan-membership Port VLAN Membership 1 1 Static 2 1 Static 3 1 Static 4 5 Static 5 5 Static 6 6 Static 7 1 Static 8 1 Static [Output Cut]Prevent VLANs from Crossing a Trunk
All VLANs are configured on a trunked link unless you clear it manually. Use the following command if you don't want a trunk to carry VLAN information: Switch1(config)#int f0/26Switch1(config-if)#clear trunkPrevent Individual VLANs from Crossing a Trunk Link
You can clear individual VLANs from crossing a trunk link by using the following command: Switch1(config)#int f0/26Switch1(config-if)#no trunk-vlan 5Verifying Trunk Link
To verify a trunk port use the show trunk [ab] command. The a is for port f0/26 while b represents f0/27. Switch1#show trunk aDISL state: Auto, Trunking: On, Encapsulation type:ISLSwitch1#show trunk allowed-vlans1-4, 6-1004Verifying VTP Information
After VTP has been enabled and configured, you can view the configuration with the following command: Switch1#show vtpVTP Version : 2Configuration Revision : 2Maximum VLANs supported locally : 1005Number of existing VLANs : 2VTP Operating Mode : ServerVTP Password : ccnaVTP Domain Name : ciscotestVTP Pruning Mode : DisabledVTP V2 Mode : DisabledVTP Traps Generation : EnabledMD5 digest : 0xB9 0xC7 0x8D 0xB3 0xD4 0xBA 0x94 0x03Configuration last modified by 192.168.1.86 at 7-25-01 01:22:24Enabling VTP Pruning
If you enable VTP pruning on a VTP server, you will enable it for the entire domain. Enable VTP pruning with the following command: Switch1(config)#vtp pruning enableDisable VTP pruning with: Switch1(config)#vtp pruning disable