ccna vs ccent

ccna vs ccent.Network management traffic includes Simple Network Management Protocol (SNMP) traffic, discussed in Chapter 17; Remote Monitoring (RMON); Spanning Tree Protocol (STP); Bridge Protocol Data Units (BPDUs), discussed in Chapter 13; Cisco Discovery Protocol (CDP) messages, discussed in Chapter 16; System Log messages, discussed in Chapter 17; Network Time Protocol (NTP ) updates, which will be discussed in Chapter 17; network device configuration backups, which will be discussed in Chapter 16; and network device operating system updates, which will be discussed in Chapter 16.Multicast is often used by video applications to deliver video streams from a server to one or more clients that want to receive them, where the transport protocol used is UDP O One video solution that uses multicast is Cisco's IP/TV Server. Video traffic is very sensitive to latency: too long a delay will be noticeable to the end user, while the video image is incoherent and out-of-phase. Latency problems can be minimized or even avoided by isolating this traffic from other traffic using VLANs and setting the necessary quality of service (QoS) for it.VoIP traffic consists of two types: signaling messages sent by VoIP phones to VoIP gateway products such as Cisco Unified Communications Manager, formerly Cisco Call Manager, and the actual voice conversation. When transporting this traffic between VoIP phones (or digital phones connected to a VoIPPBX), the transport protocol used is UDPo One problem facing VoIP traffic is that it is very sensitive to latency, and how it is mixed with other data types can create very significant performance problems for voice connections; placing this traffic in a separate VLAN and using QoS ensures that it receives a higher priority than other traffic is an important design consideration. Some Cisco Catalyst switches support a special type of VLAN-the voice VLAN.When the voice VLAN feature is enabled, the switch automatically adds Cisco VoIP phones that are connected to it to the voice VLAN. The advantage of this feature is that administrators no longer need to configure the switch to add VoIP phones connected to the network to the correct VLAN.Different types of data, such as latency-sensitive voice and video (multicast), network management traffic, and application traffic, should be segregated into different VLANs through the switch so that problems with one type of data do not affect other types of data. QoS can be used to give higher priority to traffic types such as VoIP and video, ensuring that they receive the necessary bandwidth and are treated with priority over other traffic types.12.1.4 VLAN MembershipThree methods can be used to determine which VLANs a device belongs to: static, dynamic, and voice, and these methods determine how the switch associates ports with VLANs. When using static VLANs, switch ports must be manually assigned to VLANs, for which an interface sub-configuration mode command can be used. VLANs configured in this manner are often referred to as port-based VLANsoWith dynamic VLANs, the switch automatically assigns ports to VLANs based on user device information such as MAC addresses, IP addresses, and even directory information such as user names or group names. o To do this, the switch queries a policy server, the VLAN Membership Policy Server (VMPS), which contains mapping of device information to VLANs. A switch in the network must be configured as such a server; Cisco low-end switches cannot act as VMPSs, but other switches (such as C atalyst 6500 switches) can. In this case, the low-end switch is the client, and the 6500 switch is used to store dynamic VLAN membership information.Another approach is to use 802.IX, which is used to authenticate devices connected to a switch or wireless access point, where the authentication credentials are stored on an authentication server. On the authentication server, the VLAN to which the device belongs can be used as a user account and have the server pass this information to the Layer 2 device so that the Layer 2 device can assign the port associated with the authenticated device to the appropriate VLAN OA major advantage of dynamic VLANs over static VLANs is that they support plug-and-play mobility. For example, with a dynamic VLAN, when you move a PC from one switch port to another, the latter switch port is automatically assigned to the VLAN to which the user belongs. o With a dynamic VLAN, membership information only needs to be configured when a new employee joins the company, an employee leaves the company, or a job is changed.With a static VLAN, not only do you need to manually configure the switch ports based on the latest conditions, but you must also perform manual configuration to reflect the new port to which the user is connected when the user moves from one switch to another. However, one advantage of static VLANs over dynamic VLANs is that the configuration process is simple and straightforward, whereas dynamic VLANs require a great deal of preparation to assign users to VLANs (this book discusses only static VLANs, and dynamic VLANs are outside the scope of this book). o