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On-Box Automation and Operations Tools

Chapter Description

In this chapter from Programming and Automating Cisco Networks, authors Ryan Tischer and Jason Gooley cover the following on-box automation tools in greater detail; Auto SmartPorts, AutoConf, Auto Security, AutoQoS, Smart Call Home, Tcl Shell, and Embedded Event Manager (EEM)

Quality of Service for Campus Architectures

Quality of Service (QoS) is an integral part of any campus environment. QoS allows for the prioritization of specific traffic flows as they traverse over the campus network. For example, it may be desirable to allow voice and video traffic to have priority over bulk FTP traffic during a time of network congestion. One of the most common reasons that QoS is not deployed is due to its complexity. This section will discuss some different ways to automate the deployment of QoS for LAN devices.

AutoQoS on Campus LAN Devices

As campus networks continue to grow, more emphasis is being put on the LAN. Today, it is becoming even more important to capitalize on the available LAN bandwidth as much as possible. Often, campus networks are designed with a specific set of goals in mind. For example, the following list are some of the more common business drivers and use cases that put demand on the campus LAN infrastructure:

  • Gigabit Ethernet to the desktop

  • Campus video communications

  • Voice and IP phones

Alternatively, there are some other use cases that are beginning to be more prevalent in enterprise networks. These different, but not uncommon use cases are increasing the demand for connectivity in the LAN:

  • Wayfinding devices

  • Digital signage

  • HVAC systems

  • Manufacturing/industrial networks

  • Building lighting

All of the above use cases are putting increased demand on the network and, by default, demand on the network engineering team.

Enabling AutoQoS on a Cisco Catalyst Switch

To enable AutoQoS, the following configuration steps must be followed:

  • Step 1. Enable AutoQoS globally

  • Step 2. Enable AutoQoS settings under interface

AutoQoS is enabled globally in the following example on the Catalyst switch by issuing the auto qos global compact command from the global configuration prompt. Once the feature is enabled globally, it can be verified with the show auto qos command.

Switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# auto qos global compact
Switch(config)# end
Switch# show auto qos

AutoQoS not enabled on any interface

Switch#

As you can see from the output of the show auto qos command in the following code snippet, there are no interfaces currently configured with any AutoQoS parameters. Once AutoQoS is enabled globally, you must then specify the interface configuration settings. For example, see the following output that illustrates how to enable the AutoQoS settings under a Gigabit Ethernet interface of a Catalyst switch. The configuration shown is for a Cisco IP phone.

Switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface GigabitEthernet0/1
Switch(config-if)# auto qos voip cisco-phone
Switch(config-if)# end
Switch#

Now that AutoQoS is enabled globally and there is an interface with AutoQoS settings applied to it, the show auto qos command is re-issued to verify the configuration as shown in the following snippet. Based on the output of the show auto qos command, we see that there is a difference in the information displayed as opposed to output shown previously. When AutoQoS is enabled under the GigabitEthernet0/1 interface, it now includes the interface configuration in the show command.

Switch# show auto qos
GigabitEthernet0/1
auto qos voip cisco-phone

Switch#

In order to display the actual QoS settings that get applied to the GigabitEthernet0/1 interface when a Cisco IP phone is connected, the show auto qos interface GigabitEthernet0/1 configuration command must be issued. The following snippet shows that based on the output of this command, there is an ingress policy named AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY that is applied to the GigabitEthernet0/1 interface. The output also shows that the outbound egress priority queue is enabled and that the interface has been set to automatically trust the DSCP markings from the Cisco IP phone.

Switch# show auto qos interface GigabitEthernet0/1 configuration
GigabitEthernet0/1
auto qos voip cisco-phone
Ingress Policy: AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY
Egress Priority Queue: enabled
The port is mapped to qset : 1
Trust device: cisco-phone

Next, to further validate the settings within the AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY that is applied to the GigabitEthernet0/1 interface, we issue the show policy-map AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY command as shown in the following output.

Switch# show policy-map AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY
  Policy Map AUTOQOS-PPM-SRND4-CISCOPHONE-POLICY
    Class AUTOQOS_PPM_VOIP_DATA_CLASS
      set dscp ef
      police 128000 8000 exceed-action policed-dscp-transmit
    Class AUTOQOS_PPM_VOIP_SIGNAL_CLASS
      set dscp cs3
      police 32000 8000 exceed-action policed-dscp-transmit
    Class AUTOQOS_PPM_DEFAULT_CLASS
      set dscp default
      police 10000000 8000 exceed-action policed-dscp-transmit
Switch#

Based on the previous output, we can see that the following parameters have been set in the QoS policy-map applied to the GigabitEthernet0/1 interface on the Catalyst switch:

  • Voice data packets are being marked with the DSCP value of EF (46)

  • Policing of the VOIP_DATA_CLASS is set to 128Kbps

  • Call signaling packets are being marked with the DSCP value of CS3

  • Policing of the VOIP_SIGNAL_CLASS is set to 32Kbps

  • All other packets are being marked with DSCP value of DEFAULT (0)

  • Policing of the DEFAULT_CLASS is set to 10Mbps

The following snippet illustrates the output of the show auto qos voip cisco-phone configuration command, which is an alternate way of displaying the AutoQoS configuration that will be applied to an interface when a Cisco IP phone is connected. This command will also display the DSCP/CoS markings, queuing strategy, and associated thresholds settings that will be applied.

Switch# show auto qos cisco-phone configuration
Traffic(DSCP / COS)         IngressQ-Threshold    EgressQ-Threshold
---------------------------------------------------------------------
VoIP(46/5)                         N/A - N/A             01 - 01
Signaling(24/3)                    N/A - N/A             03 - 01
Best-Effort(00/0)                  N/A - N/A             02 - 01

All of the QoS settings mentioned above were deployed by issuing only two commands: the auto qos global compact global command and the auto qos voip cisco-phone interface command. We can begin to see how powerful tools like AutoQoS can be in a campus environment, eEspecially with hundreds to thousands of connected host devices. The following section of this chapter will cover deploying AutoQoS in the campus WAN environment.

AutoQoS on Campus WAN Devices

The best practice in general from a QoS perspective is to mark the traffic closest to the source and carry those markings across your LAN and WAN end-to-end. The biggest reason for this is so that end users and applications have a consistent experience. Marking and prioritizing traffic on the LAN is just one step in a bigger QoS design. Using AutoQoS for the WAN, you can simplify the steps needed to achieve that end-to-end user and application experience. Figure 7-2 illustrates the high level end-to-end QoS design model from an IP phone in one location to an IP phone in another location.

Figure 7-2

Figure 7-2 End-to-end QoS example

As you can see based on Figure 7-2, the QoS markings are kept intact from source to destination across the campus LAN and WAN networks. In this specific case, voice data traffic from Phone-1 to Phone-2 is marked with DSCP EF (46), and those markings are honored on a hop-by-hop basis across the entire network. This is called per-hop behavior (PHB).

Enabling AutoQoS on a Cisco ISR Router

The following example lists the steps that are necessary to enable AutoQoS for the WAN on a Cisco ISR router.

Router# configure terminal
Router(config)# interface FastEthernet0/1
Router(config-if)# auto qos voip
Router(config-if)# end
Router#

One of the convenient things about AutoQoS for the WAN is that by enabling it on one of the interfaces of the router, it automatically enables the feature globally. Furthermore, it applies all the QoS policy-maps and other settings automatically. The following snippet illustrates an example output of the show auto qos command from a Cisco ISR router, illustrating what features AutoQoS will automatically activate when the feature is enabled.

Router# show auto qos
 !
 policy-map AutoQoS-Policy-UnTrust
  class AutoQoS-VoIP-RTP-UnTrust
   priority percent 70
   set dscp ef
  class AutoQoS-VoIP-Control-UnTrust
   bandwidth percent 5
   set dscp af31
  class AutoQoS-VoIP-Remark
   set dscp default
  class class-default
   fair-queue
 !
 class-map match-any AutoQoS-VoIP-Remark
  match ip dscp ef  
  match ip dscp cs3  
  match ip dscp af31  
 !
 class-map match-any AutoQoS-VoIP-Control-UnTrust
  match access-group name AutoQoS-VoIP-Control
 !
 class-map match-any AutoQoS-VoIP-RTP-UnTrust
  match protocol rtp audio  
  match access-group name AutoQoS-VoIP-RTCP
 !
 ip access-list extended AutoQoS-VoIP-RTCP
  permit udp any any range 16384 32767 (6 matches)
 !
 ip access-list extended AutoQoS-VoIP-Control
  permit tcp any any eq 1720
  permit tcp any any range 11000 11999
  permit udp any any eq 2427
  permit tcp any any eq 2428
  permit tcp any any range 2000 2002
  permit udp any any eq 1719
  permit udp any any eq 5060
 !
 rmon event 33333 log trap AutoQoS description "AutoQoS SNMP traps for Voice
Drops" owner AutoQoS
 rmon alarm 33333 cbQosCMDropBitRate.34.14175073 30 absolute rising-threshold
1 33333 falling-threshold 0 owner AutoQoS

FastEthernet0/1 -
 !
 interface FastEthernet0/1
  service-policy output AutoQoS-Policy-UnTrust

AutoQoS, in conjunction with some of the other automation mechanisms discussed earlier in the Automatic Port Profiling section of this chapter, can start to build a very robust and powerful tool set. This tool set can help network engineers ease the operational complexity of managing a constantly changing campus network environment. Chapter 8 “Network Automation Tools for Campus Environments” will highlight another tool set known as the application policy infrastructure controller enterprise module (APIC-EM). APIC-EM offers a wide variety of features that include tools to assist in configuring and automating quality of service in campus environments. We will also discuss some future APIC-EM applications.

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