Overblog Follow this blog
Administration Create my blog
Cisco & Cisco Network Hardware News and Technology

Posts with #cisco & cisco network tag

Cisco Communications Manager Express Overview

December 7 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

With the cost of high-performance networking switching equipment coming down, the implementation of alternative voice solutions has become common. There are a number of different voice solutions that utilize the existing network to provide not only a data connection but also provide a voice connection. One of these solutions that are available is Cisco Unified Communications Manager Express (CME). Cisco Unified CME provides a solution that can fill a number of different voice requirements within a small business or branch location. As well as working in these smaller environments, the Unified CME solution can also be integrated into a larger Cisco Unified Communications Manager (CUCM) solution. This article provides a high-level overview of some of the most commonly used abilities of the Unified Communications Manager Express solution.  After this overview, hopefully you will know whether or not you are in a position to install Communications Manager Express.

 

Unified Communications Manager Express Solution

As stated in the overview, the Unified CME solution can provide not only a simple voice solution that utilizes the existing data network infrastructure, but also can provide a feature rich voice solution with support for many common business voice features. The Unified Communications Manager Express solution includes support for many features including:

  • Call Hunt
  • Call Pickup
  • Call Waiting
  • Hunt Group
  • Call Park
  • Caller ID Blocking
  • Conferencing
  • Music on Hold
  • Paging

An example of how the Unified CME solution in a small office can be deployed is shown in how-the-Unified-CME-solution-in-a-small-office-can-be-deplo.png.


As seen in the figure, all of the common connections provided by a more traditional voice solution are offered. The Unified CME solution is not only able to meet the requirements of businesses but can also be deployed by service providers. One of the available solutions includes the use of an Integrated Access Device (IAD) that is deployed within the customer premises with a connection back to an integrated device running the Unified CME software. An example of this solution is shown in a-connection-back-to-an-integrated-device-running-the-Unifi.png.


As shown in the figures, the Unified CME solution is very flexible and able to provide all of the existing functionality provided by traditional telephony solutions and offers it with a cost savings and a reasonably easy configuration.

 

Unified CME Models

The Unified CME solution can be deployed in a number of ways following familiar voice deployment models. The models supported include the Private Branch Exchange (PBX) model, the Keyswitch model and a hybrid of these two models.

 

PBX Model

The PBX model follows a deployment that mimics the traditional configuration provided by a PBX; this includes the deployment of a number of different extensions (phones) that are each assigned a unique extension. Traditionally using this model, people calling in would be routed through a receptionist or an automated attendant in order to be transferred to the correct internal extension.

 

Keyswitch Model

The Keyswitch model follows a deployment that was more common on older systems (key systems) where each of the phones in the office would have a configuration that was very similar. Each of these phones would have a button that represented each of the numbers coming into the office; any one of these phones could answer and make calls on any of the lines.

 

Hybrid Model

The hybrid model provides the ability to offer the opportunity to utilize features from both the PBX and Keyswitch models. This would include the ability for a phone to have a unique extension as well as have the ability to have access to shared lines throughout the office.

 

To Sum Up

As discussed in the article, the Unified Communications Manager Express solution can offer the ability to implement a voice solution that supports a number of different features and deployed after traditional voice models. Hopefully this article and the companion articles will provide a better idea of what is possible with this solution and how it can be implemented to take advantage of equipment that supports multiple data and voice solutions.

 

More Cisco Networking News:

Cisco, VMware Doing Further on Next-gen Cloud Infrastructure

Read more

VLAN Types

November 14 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

Nowadays, there is essentially one way of implementing VLANs - port-based VLANs. A port-based VLAN is associated with a port called an access VLAN.

 

However in the network there are a number of terms for VLANs. Some terms define the type of network traffic they carry and others define a specific function a VLAN performs. The following describes common VLAN terminology:

 

Data VLAN

download--3-.png

A data VLAN is a VLAN that is configured to carry only user-generated traffic. A VLAN could carry voice-based traffic or traffic used to manage the switch, but this traffic would not be part of a data VLAN. It is common practice to separate voice and management traffic from data traffic. The importance of separating user data from switch management control data and voice traffic is highlighted by the use of a special term used to identify VLANs that only carry user data - a "data VLAN". A data VLAN is sometimes referred to as a user VLAN.

 

Default VLAN

All switch ports become a member of the default VLAN after the initial boot up of the switch. Having all the switch ports participate in the default VLAN makes them all part of the same broadcast domain. This allows any device connected to any switch port to communicate with other devices on other switch ports. The default VLAN for Cisco switches is VLAN 1.

 

VLAN 1 has all the features of any VLAN, except that you cannot rename it and you cannot delete it. Layer 2 control traffic, such as CDP and spanning tree protocol traffic, will always be associated with VLAN 1 - this cannot be changed. In the figure, VLAN 1 traffic is forwarded over the VLAN trunks connecting the S1, S2, and S3 switches. It is a security best practice to change the default VLAN to a VLAN other than VLAN 1; this entails configuring all the ports on the switch to be associated with a default VLAN other than VLAN 1. VLAN trunks support the transmission of traffic from more than one VLAN. Although VLAN trunks are mentioned throughout this section, they are explained in the next section on VLAN trunking.

 

Note: Some network administrators use the term "default VLAN" to mean a VLAN other than VLAN 1 defined by the network administrator as the VLAN that all ports are assigned to when they are not in use. In this case, the only role that VLAN 1 plays is that of handling Layer 2 control traffic for the network.

 

Native VLAN

A native VLAN is assigned to an 802.1Q trunk port. An 802.1Q trunk port supports traffic coming from many VLANs (tagged traffic) as well as traffic that does not come from a VLAN (untagged traffic). The 802.1Q trunk port places untagged traffic on the native VLAN. In the figure, the native VLAN is VLAN 99. Untagged traffic is generated by a computer attached to a switch port that is configured with the native VLAN. Native VLANs are set out in the IEEE 802.1Q specification to maintain backward compatibility with untagged traffic common to legacy LAN scenarios. For our purposes, a native VLAN serves as a common identifier on opposing ends of a trunk link. It is a best practice to use a VLAN other than VLAN 1 as the native VLAN.

  

Management VLAN

A management VLAN is any VLAN you configure to access the management capabilities of a switch. VLAN 1 would serve as the management VLAN if you did not proactively define a unique VLAN to serve as the management VLAN. You assign the management VLAN an IP address and subnet mask. A switch can be managed via HTTP, Telnet, SSH, or SNMP. Since the out-of-the-box configuration of a Cisco switch has VLAN 1 as the default VLAN, you see that VLAN 1 would be a bad choice as the management VLAN; you wouldn't want an arbitrary user connecting to a switch to default to the management VLAN. Recall that you configured the management VLAN as VLAN 99 in the Basic Switch Concepts and Configuration chapter.

 

Voice VLANs

download--2-.png
It is easy to appreciate why a separate VLAN is needed to support Voice over IP (VoIP). Imagine you are receiving an emergency call and suddenly the quality of the transmission degrades so much you cannot understand what the caller is saying. VoIPtraffic requires:

Assured bandwidth to ensure voice quality 
Transmission priority over other types of network traffic
Ability to be routed around congested areas on the network
Delay of less than 150 milliseconds (ms) across the network

To meet these requirements, the entire network has to be designed to support VoIP. The details of how to configure a network to support VoIP are beyond the scope of the course, but it is useful to summarize how a voice VLAN works between a switch, a Cisco IP phone, and a computer.

In the figure, VLAN 150 is designed to carry voice traffic. The student computer PC5 is attached to the Cisco IP phone, and the phone is attached to switch S3. PC5 is in VLAN 20, which is used for student data. The F0/18 port on S3 is configured to be in voice mode so that it will tell the phone to tag voice frames with VLAN 150. Data frames coming through theCisco IP phone from PC5 are left untagged. Data destined for PC5 coming from port F0/18 is tagged with VLAN 20 on the way to the phone, which strips the VLAN tag before the data is forwarded to PC5. Tagging refers to the addition of bytes to a field in the data frame which is used by the switch to identify which VLAN the data frame should be sent to. 
 
A Cisco Phone is a Switch
download--1-.png
The Cisco IP Phone contains an integrated three-port 10/100 switch as shown in the Figure. The ports provide dedicated connections to these devices:

Port 1 connects to the switch or other voice-over-IP (VoIP) device.
Port 2 is an internal 10/100 interface that carries the IP phone traffic.
Port 3 (access port) connects to a PC or other device.

The figure shows one way to connect an IP Phone.

The voice VLAN feature enables switch ports to carry IP voice traffic from an IP phone. When the switch is connected to an IP Phone, the switch sends messages that instruct the attached IP phone to send voice traffic tagged with the voice VLAN ID 150. The traffic from the PC attached to the IP Phone passes through the IP phone untagged. When the switch port has been configured with a voice VLAN, the link between the switch and the IP phone acts as a trunk to carry both the tagged voice traffic and untagged data traffic.
download.png

Sample Configuration
The figure shows sample output. A discussion of the Cisco IOS commands are beyond the scope of this course, but you can see that the highlighted areas in the sample output show the F0/18 interface configured with a VLAN configured for data (VLAN 20) and a VLAN configured for voice (VLAN 150). 

--- Reference from http://ccnaanswers-khim.blogspot.com/2011/05/types-of-vlans.html

More Related Networking Tips:

‘What Happens in the VLAN Stays in the VLAN?’

How Private VLANs Work?

How to Configure Private VLANs on Cisco 3560 Switches?

VLAN Trunking Protocol (VTP) & VTP Modes

Types of Networks

VLAN Switch Port Modes

Read more

Tips to Configure VLAN on a Cisco Switch

November 8 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

VLAN stands for virtual LAN and technically we can say, a VLAN is a broadcast domain created by switch. When managing a switch, the management domain is always VLAN 1, the default VLAN. All ports of switch are assigned to VLAN 1 by default.  VLAN increase the performance of a network because it divide a network logically in different parts and limit the broadcasts.

 Configure-VLAN-on-a-Cisco-Switch.jpg

Any member of VLAN 2 cannot talk with any member of VLAN 3 without router but all the members of VLAN 2 and VLAN 3 can talk with other members within their VLANs.

 

This Lab will also help how VLANs can be used to separate traffic and reduce broadcast domains. 

To create a VLAN, first enter global configuration mode to run the following commands.

 

Configuration to create VLAN 2 

SwitchA(config)#configure terminal               (enter in global configuration mode) 

SwitchA(config)#vlan 2                                        (defining the vlan 2) 

SwitchA(config)#vlan 2 name marketing       (assigning the name marketing to vlan 2)

SwitchA(config)#exit        (exit from vlan 2) 

 

Configuration to create VLAN 3 

SwitchA(config)#configure terminal                 (enter in global configuration mode) 

SwitchA(config)#vlan 3                                        (defining the vlan 3) 

SwitchA(config)#vlan 3 name management      (assigning the name management to vlan 3)

SwitchA(config)#exit        (exit from vlan 3)

 

Now assigning the ports 2 and 3 to VLAN 2, it must be done from the interface mode. Enter the following commands to add port 2 and 3 to VLAN 2. 

SwitchA(config)#configure terminal                                 (enter in global configuration mode) 

SwitchA(config)#interface fastethernet 0/2                     (select the Ethernet 0 of port 2) 

SwitchA(config-if)#switchport access vlan 2                  (allot the membership of vlan 2)

SwitchA(config-if)#exit                                                        (exit from interface 2)

 

Now adding port 3 to VLAN 2 

SwitchA(config)#interface fastethernet 0/3                     (select the Ethernet 0 of port 3) 

SwitchA(config-if)#switchport access vlan 2                  (allot the membership of vlan 2)

SwitchA(config-if)#exit                                                        (exit from interface 3) 

 

Now assigning the ports 4 and 5 to VLAN 3, enter the following commands to add port 4 and 5 to VLAN 3. 

SwitchA(config)#configure terminal                                 (enter in global configuration mode) 

SwitchA(config)#interface fastethernet 0/4                     (select the Ethernet 0 of port 4) 

SwitchA(config-if)#switchport access vlan 3                  (allot the membership of vlan 3)

SwitchA(config-if)#exit                                                        (exit from interface 4) 

 

Now adding port 5 to VLAN 3 

SwitchA(config)#interface fastethernet 0/5                     (select the Ethernet 0 of port 5) 

SwitchA(config-if)#switchport access vlan 3                  (allot the membership of vlan 3)

SwitchA(config-if)#exit                                                        (exit from interface 5) 

 

More Cisco Switch Tips and Tutorials you can visit http://blog.router-switch.com/category/reviews/cisco-switches/

Read more

Cisco VTP: VLAN Trunking Protocol---VTP Versions’ Difference

November 1 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

VLAN Trunking Protocol (VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. Virtual Local Area Network (VLAN) Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst Family products.

 

VTP ensures that all switches in the VTP domain are aware of all VLANs. There are occasions, however, when VTP can create unnecessary traffic. All unknown unicasts and broadcasts in a VLAN are flooded over the entire VLAN. All switches in the network receive all broadcasts, even in situations where few users are connected in that VLAN. VTP pruning is a feature used to eliminate (or prune) this unnecessary traffic.

 

By default, all Cisco Catalyst switches are configured to be VTP servers. This is suitable for small-scale networks where the size of the VLAN information is small and easily stored in all switches (in NVRAM). In a large network, a judgment call must be made at some point when the NVRAM storage needed is wasted, because it is duplicated on every switch. At this point, the network administrator should choose a few well-equipped switches and keep them as VTP servers. Everything else participating in VTP can be turned into a client. The number of VTP servers should be chosen so as to provide the degree of redundancy desired in the network.

 

There are three version of VTP so far. VTP Version 2 (V2) is not much different than VTP Version 1 (V1). The major difference is that VTP V2 introduces the support for Token Ring VLANs. If you are using Token Ring VLANs, you need to enable VTP V2. Otherwise, there is no reason to use VTP V2. VTP version 3 differs from earlier VTP versions in that it does not directly handle VLANs. VTP version 3 is a protocol that is only responsible for distributing a list of opaque databases over an administrative domain. When enabled, VTP version 3 provides the following enhancements to previous VTP versions:

  • Support for extended VLANs.
  • Support for the creation and advertising of private VLANs.
  • Improved server authentication.
  • Protection from the "wrong" database accidentally being inserted into a VTP domain.
  • Interaction with VTP version 1 and VTP version 2.
  • Provides the ability to be configured on a per-port basis.
  • Provides the ability to propagate the VLAN database another databases.

 

Protocol Structure - VTP: VLAN Trunking Protocol

The format of the VTP header can vary depending on the type of VTP message. However, they all contain the following fields in the header:

  • VTP protocol version: 1 or 2 or 3
  • VTP message types:
    • Summary advertisements
    • Subset advertisement
    • Advertisement requests
    • VTP join messages
  • Management domain length
  • Management domain name

 

Summary Advertisements

When the switch receives a summary advertisement packet, it compares the VTP domain name to its own VTP domain name. If the name is different, the switch simply ignores the packet. If the name is the same, the switch then compares the configuration revision to its own revision. If its own configuration revision is higher or equal, the packet is ignored. If it is lower, an advertisement request is sent.

  • Followers indicate that this packet is followed by a Subset Advertisement packet.
  • The updater identity is the IP address of the switch that is the last to have incremented the configuration revision.
  • Update timestamps are the date and time of the last increment of the configuration revision.
  • Message Digest 5 (MD5) carries the VTP password if it is configured and used to authenticate the validation of a VTP update.

Summary-Advertisements.jpg 

Subset Advertisements

When you add, delete, or change a VLAN in a switch, the server switch where the changes were made increments the configuration revision and issues a summary advertisement, followed by one or several subset advertisements. A subset advertisement contains a list of VLAN information. If there are several VLANS, more than one subset advertisement may be required in order to advertise them all.

Subset-Advertisements.jpg

The following formatted example shows that each VLAN information field contains information for a different VLAN (ordered with lowered-valued ISL VLAN IDs occurring first):

Subset-Advertisements-1.jpg

Most of the fields in this packet are easy to understand. Below are two clarifications:

  • Code- The format for this is 0x02 for subset advertisement.
  • Sequence number- This is the sequence of the packet in the stream of packets following a summary advertisement. The sequence starts with 1. 

 

Advertisement Requests

A switch needs a VTP advertisement request in the following situations:

  • The switch has been reset.
  • The VTP domain name has been changed.
  • The switch has received a VTP summary advertisement with a higher configuration revision than its own.

 

Upon receipt of an advertisement request, a VTP device sends a summary advertisement, followed by one or more subset advertisements. Below is an example.

Subset-Advertisements-2.jpg

  • Code- The format for this is 0x03 for an advertisement request
  • Starts Value - This is used in cases where there are several subset advertisements. If the first (N) subset advertisement has been received and the subsequent one (N+1) has not, the Catalyst only requests advertisements from the (N+1)th one.

---Reading Resource from http://www.javvin.com/protocolVTP.html

More Cisco VTP Tips:

Cisco VTP Version 3, Is VTP Making a Comeback?

VLAN Trunking Protocol (VTP) & VTP Modes

Read more

Quick Q and A to know Cisco SMARTnet Service.

October 17 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

What is Cisco SMARTnet Service?

Cisco SMARTnet Service is an award-winning technical support service that can give your IT staff direct, anytime access to Cisco experts and online self-help resources required to resolve issues with most Cisco products. With SMARTnet Service, you can choose from a broad range of service delivery options for Cisco products.

 Cisco-SMARTnet-Service-Overview.jpg

What is included with Cisco SMARTnet Service?

Cisco SMARTnet Service provides the following device-level support:

Direct access 24 hours a day, 365 days a year to specialized experts in the Cisco Technical Assistance Center (TAC).

Extensive self-help support through Cisco’s online knowledge base, communities, resources, and tools.

Smart, proactive diagnostics and immediate alerts on select devices enabled with Cisco Smart Call Home feature.

Operating system (OS) software updates, including both minor and major releases within your licensed feature set.

Advance hardware replacement options, including 2-hour, 4-hour, and next-business-day (NBD) replacement, as well as return for repair (RFR).

Optional onsite service that provides a field engineer who can install replacement parts at your location.

Increase ROI by up to 192 percent having access to Cisco operating system software enhancements

Expedite time to repair with the right parts at the right time to resolve issues quickly

Better manage scarce internal expert resources at all locations when utilizing the proactive diagnostics and realtime alerts available with Smart Call Home, on select devices

Empower your IT staff and improve productivity and revenue per employee with access to tools and technical support documentation that can increase self-sufficiency and technical knowledge

 

Why should you purchase Cisco SMARTnet Service?

By covering networking devices with a Cisco SMARTnet contract, you can:

Improve network availability, reliability, stability, and security with direct access to networking engineers at Cisco

Reduce the cost of network ownership by using Cisco expertise, knowledge, and availability

 

Is Cisco SMARTnet Service only limited to break/fix insurance?

No. The Cisco SMARTnet Service offers you help handling complex network operation and management issues such as:

Advance software configuration

Interoperability and upgrade questions

Hardware and software information

In addition, Cisco SMARTnet Service helps you protect your network investments and minimize risks by:

Keeping your networking technology up-to-date with the latest OS software features and system improvements within your licensed feature set

Supplementing your network support organization to help ensure the availability of the knowledge and skills necessary to address rapidly changing technologies

Providing access to knowledgeable resources and tools for rapid resolution of issues

Eliminating the challenges of carrying replacement hardware in inventory and delivering them to remote sites

Providing optional trained field engineering resources to perform replacement services when and where you need them

Troubleshooting Call Home-capable devices in real time and reporting details back to you using a web portal and alerts using Smart Call Home

 

What additional features are available under the Cisco SMARTnet onsite option?

Cisco SMARTnet onsite includes the same capabilities as Cisco SMARTnet, with the addition of an onsite technician for parts replacement and installation. It is available with all SMARTnet advance hardware replacement service levels.

 

How should you choose between Cisco SMARTnet and Cisco SMARTnet onsite?

Cisco SMARTnet onsite support is the appropriate choice when:

You do not have the appropriate expert resources at a given site, such as a remote site.

Trained personnel are not readily available to react quickly to a network issue. The Cisco SMARTnet onsite service option provides rapid replacement of hardware.

 

Features and Benefits: Service Capabilities

What are service capabilities for SMARTnet?

Table 1 illustrates SMARTnet’s five main service capabilities.

Table 1. Cisco SMARTnet Service Capabilities

Cisco-SMARTnet-Service-Capabilities.jpg

1. Return for repair on select video products only.

Expert assistance: To complement your in-house resources, the Cisco TAC employs a highly skilled staff that offers you years of networking experience, including many customer support engineers with networking and CCIE certifications as well as research and development engineers. Cisco engineers hold more than 800 U.S.-issued patents and have authored numerous industry white papers and books.

Faster resolution: The Cisco TAC provides constant measurement of customer satisfaction and time-toresolution tracking, including an automated escalation sequence beginning one hour after submittal of severity 1 and severity 2 issues, resulting in CEO intervention by John Chambers after 48 hours for any severity 1 problem.

For more information, view the Cisco Severity and Escalation Guidelines.

http://www.cisco.com/web/about/doing_business/legal/service_descriptions/docs/Cisco_Severity_and_Escalation_Guidelines.pdf

Visibility into issue resolution status: You are kept up-todate on all changes to your case through email notifications and personalized handoffs between you and Cisco engineers if your case warrants a move to a new specialization due to the nature of the issue, or a change occurs in work shift.

Networking expertise: The Cisco TAC offers depth and breadth of knowledge and experience with Cisco devices and operating system software, as well as a broad range of networking environments and technologies. Cisco TAC engineers have a minimum of five years of industry experience, and Cisco provides continuous training to help ensure our technical staff stays current with the latest technologies.

Support 24 hours a day, 365 days a year in multiple languages: By telephone, web, or email, the Cisco TAC is there when you need it.

Tested and proven resolution methods: Cisco uses a powerful virtual lab as an invaluable engineering resource and knowledge base for testing of network problems and recommended resolutions.

 

Can I get support from the Cisco TAC if I do not have a service contract?

Yes. The Cisco TAC will help you if you do not have a Cisco service contract, but you will be requested to pay a “perincident fee” or to purchase a service contract.

 

How does the Cisco TAC prioritize service requests?

Cisco processes allow for you to designate the severity of every service request reported. Problems are reported in a standard format using the following problem severity definitions:

Severity 1: When an existing network or environment is down or there is a critical impact on the end user’s business operations. Cisco and the end user will commit full-time resources to resolve the situation.

Severity 2: When the operation of an existing network or environment is severely degraded or significant aspects of the end user’s business operation are being negatively affected by unacceptable network performance. Cisco and the end user will commit full-time resources during standard business hours to resolve the situation.

Severity 3: When the operational performance of the network or environment is impaired while most business operations remain functional. Cisco and the end user are willing to commit resources during standard business hours to restore service to satisfactory levels.

Severity 4: When information is required on Cisco product capabilities, installation, or configuration and there is little or no effect on the end user’s business operation. Cisco and the customer are willing to provide resources during standard business hours to provide information or assistance as requested.

 

More Related Cisco SMARTnet Service you can read at

http://www.cisco.com/en/US/services/ps2827/ps2978/services_qa0900aecd8042b4d6.pdf

Cisco SMARTnet Service-IMPROVE NETWORK & IT INFRASTRUCTURE PRODUCT AVALABILITY

Cisco Smart Care Service

http://www.cisco.com/en/US/services/ps2827/ps7343/services_qa0900aecd8061279a.pdf

Read more

QoS Classification and Marking Configuration

September 10 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

In this article we will share the details for proper QoS Marking and Classification configuration. As discussed in the VoIP Quality of Service (QoS) Basics article, the first thing that must be accomplished when configuring QoS is the classification and marking of traffic; this marking is then used by the devices on the network to prioritize high priority over low priority marked traffic. This article discusses the commonly used Differentiated Services Code Point (DSCP) values and the basic concepts of classification and marking. The article then goes on to show the basic configuration steps required to implement traffic classification and marking.

 

The material in this article can be used as a jumping off point for studying for the CCNP Voice certification as this material is found in the CVOICE (642-437) exam that must be passed to obtain this certification. With the integration of voice and video becoming more and more common on modern networks, a solid understanding of what is possible with QoS is essential.

 

DSCP - Per Hob Behaviors (PHB)

The purpose of DSCP is to differentiate the different classes or types of traffic on the network; the DSCP section takes up the first 6 bits of the Type of Service field in the IP header. This space was previously used for IP precedence, and while some older implementations may still use IP precedence, most modern implementations have moved over to using DSCP. The value contained within the DSCP section is called a Per Hob Behavior (PHB); the PHB is what dictates how the traffic is handled when being routed through a network.

 

There are four PHB classes:

  1. Default
  2. Class Selector (CS)
  3. Assured Forwarding (AF)
  4. Expedited Forwarding (EF)

 

The Default class (000000) is typically used as a catch-all for all traffic that does not require a specific priority over the network; this traffic is handled as best effort going across the network. This means simply that the traffic is routed as the resources of the forwarding devices allow.

The Class Selector type is used in order to remain backward compatible with existing IP precedence implementations, the last three bits of the CS DHCP is always 000 with the first three bits being set based on the values of IP precedence, i.e., IP Precedence 7 would be 111000. The CS DHCP values that are typically used are DSCP 8 (001000), 16 (010000), 24 (011000), 32 (100000), 40 (101000), 48 (110000), and 56 (111000).

 

The Assured Forwarding type provides a framework of traffic classes; these are detailed inTable 1.

TABLE 1

Drop Probability

Class 1

Class 2

Class 3

Class 4

Low Drop

AF11 

DSCP 10

'001010'

AF21 

DSCP 18

'010010'

AF31 

DSCP 26

'011010'

AF41 

DSCP 34

'100010'

Medium Drop

AF12 

DSCP 12

'001100'

AF22 

DSCP 20

'010100'

AF32 

DSCP 28

'011100'

AF42 

DSCP 36

'100100'

High Drop

AF13 

DSCP 14

'001110'

AF23 

DSCP 22

'010110'

AF33 

DSCP 30

'011110'

AF43 

DSCP 38

'100110'

 

The Expedited Forwarding type is used to dignify the highest traffic priority; the EF PHB uses a DSCP value of 46 or 101110. This type is typically used on voice and video traffic when it is being passed over a common data network.

 

Traffic Classification and Marking Configuration

The first thing to note here is that this article is focusing on how traffic classification and traffic marking work together. However, traffic classification can be used for a number of different purposes including use with traffic management. If there is a serious interest in learning all the capabilities of traffic classification, please review the IOS QoS guide available at http://www.cisco.com.

 

To perform traffic classification and marking, the Modular QoS Command Line Interface (MQC) is used. The MQC follows a basic structure regardless of what task is being completed, this structure includes:

  • Defining a traffic class, with matching criteria
  • Creating a traffic policy, that is used to define QoS actions
  • Apply the traffic policy, to a specific interface or sub-interface

 

Defining a Traffic Class

The definition of a traffic class is where traffic classification occurs. It is during this part of configuration that the specific traffic that is to be matched is configured. There are a number of different ways that can be used to match specific traffic; some of the available options are included in Table 2.

 

TABLE 2

Match Command

Match Criteria

match access group

Matches based on a predefined access-list

match cos

Matches based on traffic with a specific Class of Service (CoS) value

match dscp

Matches based on traffic with a specific Differentiated Services Code Point (DSCP) value

match precedence

Matches based on traffic with a specific IP precedence value

match protocol protocol

Matches based on the traffic classified by the Network-based application recognition feature. 

The basic syntax to define a traffic class is:

  • router(config)#class-map class-map-name [match-all | match-any]
  • router(config-cmap)#match (See Table 2)

 

Creating a Traffic Policy

A traffic policy defines how to handle the traffic that was matched within the class-map command; this is where traffic marking can occur. There are a number of different supported traffic policy commands. However, as related to traffic marking, the commands in Table 3 are commonly used:

 

TABLE 3

Set command

Traffic attribute

set cos

Sets the value of the CoS field

set dscp

Sets the value of the DSCP field

set precedence

Sets the value of the IP precedence field.

 

The basic syntax to create a traffic policy is:

  • router(config)#policy-map policy-map-name
  • router(config-pmap)#class {class-name | class-default} (This comes from the class-mapcommand)
  • router(config-pmap-c)#set (see Table 3)

 

Apply the Traffic Policy

Of course, the creation of a traffic class and a traffic policy will do very little if it is not applied to a specific interface or subinterface. Traffic policies are applied to an interface in a specific direction, ensuring that the configured direction provides the expected results. Typically, when classifying traffic from an external source, the traffic will be classified and marked at the perimeter of the network coming in to the network.

The basic syntax to apply a traffic policy is:

  • router(config)#interface type number
  • router(config-if)#service-policy {input output} policy-map-name

 

The concepts used to classify and mark traffic are not hard to understand once the basics are made clear. Hopefully, this article gives a good base for understanding how Quality of Service is implemented on Cisco equipment, specifically QoS Classification and Marking Configuration.

--- Original reference from http://www.petri.co.il/qos-marking-and-classification.htm

More…

Basic Overview of Cisco Voice over IP (VoIP) QoS

How to Prepare for the CCIE Voice Written Exam?

Top 5 VoIP Concepts to Know for CCNA Voice

Read more

10 Commands You Need to Know When Using the Cisco IOS

August 6 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

Preface: Becoming proficient with the Cisco IOS means learning some essential commands. This quick reference describes 10 commands you’ll need to rely on when handling various configuration and troubleshooting tasks.

The Cisco IOS provides thousands of commands, and configuring it can be challenging. Here are 10 commands you need to know, inside and out, when using the Cisco IOS.Cisco-IOS-Commands.JPG

#1: The “?”

It may seem entirely too obvious that you should know how to type ? to ask for help when using the Cisco IOS. However, the Cisco IOS is completely different from other operating systems when it comes to using the question mark (help key). As the IOS is a command-line operating system with thousands of possible commands and parameters, using the ? can save your day.

 

You can use the command in many ways. First, use it when you don’t know what command to type. For example, type ? at the command line for a list of all possible commands. You can also use ? when you don’t know what a command’s next parameter should be. For example, you might typeshow ip ? If the router requires no other parameters for the command, the router will offer CR as the only option. Finally, use ? to see all commands that start with a particular letter. For example,show c? will return a list of commands that start with the letter c.

 

#2: show running-configuration

The show running-config command shows the router, switch, or firewall’s current configuration. The running-configuration is the config that is in the router’s memory. You change this config when you make changes to the router. Keep in mind that config is not saved until you do a copy running-configuration startup-configuration. This command can be abbreviated sh run.

 

#3: copy running-configuration startup-configuration

This command will save the configuration that is currently being modified (in RAM), also known as the running-configuration, to the nonvolatile RAM (NVRAM). If the power is lost, the NVRAM will preserve this configuration. In other words, if you edit the router’s configuration, don’t use this command and reboot the router–those changes will be lost. This command can be abbreviatedcopy run start. The copy command can also be used to copy the running or startup configuration from the router to a TFTP server in case something happens to the router.

 

#4: show interface

The show interface command displays the status of the router’s interfaces. Among other things, this output provides the following:

  • Interface status (up/down)
  • Protocol status on the interface
  • Utilization
  • Errors
  • MTU

This command is essential for troubleshooting a router or switch. It can also be used by specifying a certain interface, like shint fa0/0.

 

#5: show ip interface

Even more popular than show interface are show ip interface and show ip interface brief. Theshow ip interface command provides tons of useful information about the configuration and status of the IP protocol and its services, on all interfaces. The show ip interface brief command provides a quick status of the interfaces on the router, including their IP address, Layer 2 status, and Layer 3 status.

 

#6: config terminal, enable, interface, and router

Cisco routers have different modes where only certain things can be shown or certain things can be changed. Being able to move between these modes is critical to successfully configuring the router.

 

For example, when logging in, you start off at the user mode (where the prompt looks like >). From there, you type enable to move to privileged mode (where the prompt looks like #). In privileged mode, you can show anything but not make changes. Next, type config terminal (or config t) to go to global configuration mode (where the prompt looks like router(config)# ). From here, you can change global parameters. To change a parameter on an interface (like the IP address), go to interface configuration mode with the interface command (where the prompt looks like router(config-if)#). Also from the global configuration mode, you can go into router configuration using the router {protocol} command. To exit from a mode, type exit.

 

#7: no shutdown

The no shutdown command enables an interface (brings it up). This command must be used in interface configuration mode. It is useful for new interfaces and for troubleshooting. When you’re having trouble with an interface, you may want to try a shut and no shut. Of course, to bring the interface down, reverse the command and just say shutdown. This command can be abbreviatedno shut.

 

#8: show ip route

The show ip route command is used to show the router’s routing table. This is the list of all networks that the router can reach, their metric (the router’s preference for them), and how to get there. This command can be abbreviated shipro and can have parameters after it, like shiproospffor all OSPF routers. To clear the routing table of all routes, you do clear ip route *. To clear it of just one route, do clear ip route 1.1.1.1 for clearing out that particular network.

 

#9: show version

The show version command gives you the router’s configuration register (essentially, the router’s firmware settings for booting up), the last time the router was booted, the version of the IOS, the name of the IOS file, the model of the router, and the router’s amount of RAM and Flash. This command can be abbreviated shver.

 

#10: debug

The debug command has many options and does not work by itself. It provides detailed debugging output on a certain application, protocol, or service. For example, debug ip route will tell you every time a router is added to or removed from the router.

 

More Cisco IOS Commands Tips:

Top Five Cisco IOS Commands Every Network Admin Should Know

How to Configure IPSEC Encryption with the Cisco IOS?

Configuring Local Username Database in Cisco IOS

Read more

How to Select Your Cisco Products?

July 30 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco & Cisco Network

 

Today, WAN technologies most often take advantage of high-speed connections, such as T-1 and E-1. Additional WAN technologies exist, including Frame Relay, ISDN, and dial-up asynchronous connections. ISDN or dial-up is used if infrequent connection is made. If a connection is used for more than two to four hours, you should use a Frame Relay or a leased line. Based on the different services available through the service provider, you can select Cisco products that can fulfill your office requirements.Select-Your-Cisco-Products.jpg

Selecting Hubs

Cisco has various hub products. You can select hubs according to the type of connection required. Higher-end hubs offer network management port and console connections, middle-end hubs offer both 10 Mbps and 100 Mbps auto-sensing connections, and the lower-end hubs offer only 10 Mbps connections. Examples of fast hub series of Cisco are Cisco Fh100, Cisco Fh200, Cisco Fh300, and Cisco Fh400. Examples of micro hub series are Cisco MH1500 and Cisco MH1528.

Selecting Routers

Routers are the most popular Cisco products. To select a router, you must first know the port density and the interface speed required based on the LAN or WAN technologies used. In addition, you must identify the capacity and performance requirements of your business. The cost of the router varies according to the features you select.

Selecting Switches

A switch can be used instead of a hub in newer networks. Most switches are configured to limit collision domains, which often provides a limited security feature because users will not be able to sniff traffic as easily as in a standard hub-based network. This feature can cause confusion when using a network sniffer to analyze traffic. It is possible, however, to analyze packets on a switched network by enabling mirroring on the switch, or by using a dedicated port that allows authorized users to view all network traffic. It is important to consider whether you need 10, 100, or 1000 Mbps for each desktop or to connect between switches. To select a switch, you must consider various issues, such as business requirements, requirements for inter-switch links and trunking, port density, and type of user interface.

Product Selection Criteria

When selecting the right products for any network environment, keep the following considerations in mind:

  • Will the device be used as a core device, distribution device, or access device?
  • Does the device provide the functions that your business requires?
  • Does the device have adequate number of ports and the right mix of interfaces as required by your business?
  • Do you have to pay a lot for installing the device or can it be easily installed?
  • Can the device be centrally managed from an SNMP Management station or do you have to physically access the device to manage it?
  • Is the migration path easy?
  • How well does the device handle redundancy requirements?
  • Do you have to change your existing infrastructure, such as cabling or existing devices, to install the new device? You may use the Cisco’s official website to gather more information to select products based on your requirements.

 

More Info and Tips of Selecting Cisco Hardware

How to select a very right router for home or business?

Buy used cisco hardware vs. new cisco equipment

 

Read more
<< < 1 2 3 4 5 6 7