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Configuring Application Aware Routing

Configuring Application Aware Routing

Posted on Jan 27, 2020 (0)

Configuring Application Aware Routing

Application-aware routing policy affects traffic which flows from Service Side VPN to Tunnel WAN side of vEdge Router.

This policy matches the application with SLA, which is data plane tunnel performance characteristic which is necessary to transfer that application data traffic and which helps to optimize the path for data traffic being transmitted by vEdge Router.

An application-aware routing policy comes under centralized data policy which is configured on vSmart controller and the vSmart will push it to all affected vEdge router. This policy contains a series of sequence filled with match-action pairs that are evaluated in order from lowest to highest sequence and when any data packet match the match conditions , SLA action is applied to packet to determine data tunnel used for transmit packet . If no match occurs and if no default SLA class is configured, packet is accepted and forwarded with no consideration of SLA.

Application-Aware policy also accepts the nonmatching traffic by default so it is said as positive policy and other type of policy are negative policies because by default it drops non matching traffic.

CLI Configure Procedure:

Create a list of SDWAN Viptela overlay sties on which the application-aware routing policy is to be applied (in the apply-policy command):

vSmart(config)# policy
vSmart(config-policy)# lists site-list list-name
vSmart(config-site-list)# site-id site-id

Create SLA classes and traffic characteristics which will be used by application data traffic to match:

vSmart(config)# policy sla-class sla-class-name
vSmart(config-sla-class)# jitter milliseconds
vSmart(config-sla-class)# latency milliseconds
vSmart(config-sla-class)# loss percentage

For identification of application traffic of interest create lists of applications, IP prefixes, and VPNs

vSmart(config)# policy lists
vSmart(config-lists)# app-list list-name
vSmart(config-app-list)# (app application-name | app-family family-name)
vSmart(config-lists)# prefix-list list-name
vSmart(config-prefix-list)# ip-prefix prefix/length
vSmart(config-lists)# vpn-list list-name
vSmart(config-vpn-list)# vpn vpn-id

 Create instance of an application-aware routing policy and associate it with a list of VPNs:

vSmart(config)# policy app-route-policy policy-name
vSmart(config-app-route-policy)# vpn-list list-name

Within the policy, create one or more numbered sequences of match–action pairs, where the match parameters define the data traffic and applications of interest and the action parameters specify the SLA class to apply if a match occurs.

Create a sequence

vSmart(config-app-route-policy)# sequence number

Define match parameters for data packets:

vSmart(config-sequence)# match parameters

Define the action to take if a match occurs with any combinations:

  • (Option 1) Define SLA class. If no available tunnels meet the SLA criteria, drop traffic:

vSmart(config-sequence)# action sla-class sla-class-name strict

  • (Option 2) Define SLA class. If no available tunnels meet the SLA criteria, use the tunnel color specified as backup:

vSmart(config-sequence)# action sla-class sla-class-name
vSmart(config-sequence)# action backup-sla-preferred-color colors

  • (Option 3) Define SLA class and preferred tunnel color. If no available tunnels meet the SLA criteria, drop traffic:

vSmart(config-sequence)# action sla-class sla-class-name preferred-color colors strict

  • (Option 4) Define SLA class and preferred tunnel color. If no available tunnels meet the primary SLA criteria, use the tunnel color specified as backup:

vSmart(config-sequence)# action sla-class sla-class-name preferred-color colors
vSmart(config-sequence)# action backup-sla-preferred-color colors

The Preferred-color identify to use the specific tunnel when data traffic matches SLA class. If more than one tunnel match the SLA, traffic is sent to preferred tunnel and if preferred color tunnel is not available, traffic is sent to any available tunnel

Strict or backup-sla-preferred-color is used to determine how to handle data traffic if no tunnel matches SLA. Use strict keyword to drop traffic if no tunnel match SLA.

If a data packet does not match any condition, a default action is taken which will accept all non-matching traffic and forward it with no SLA consideration by following configuration.

vSmart(config-policy-name)# default-action sla-class sla-class-name

Apply the policy to a site list:

vSmart(config)# apply-policy site-list list-name app-route-policy policy-name

SLA Class:

SLA class is set of parameter which defines maximum jitter, maximum latency, maximum packet loss which is application aware routing policy uses to select best path. Following are the parameters used:

  • Jitter milliseconds (1 through 1000 milliseconds)
  • Latency Milliseconds (1 through 1000 milliseconds)
  • Loss percentage ( o through 100 percent )

Match Parameter:

Following are the match parameter which Application-aware routing policy matches IP Prefixes, and fields in IP header.

  • Match all packets:  Omit match command
  • Application or Application families:  app-list listname
  • Group of destination prefixes: destinationdata- prefixlist listname
  • Destination port number: destinationport number  0 through 65535.
  • DSCP value: dscp number 0 through 63
  • Internet Protocol number: protocol number 0 through 255
  • Packet loss priority (PLP): plp (high | low) By default, packets have a PLP value of low.

How Application Aware Routing policy is applied with combination with other Data policies:


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