This article describes how to rate-limit SD-WAN traffic on Versa FlexVNF

Use Case

In some scenarios, customer wants to limit/rate-limit the SD-WAN traffic.

For example In Hub-Spoke topology customer might want to rate-limit the SD-WAN traffic on spoke site to avoid congestion on HUB site.

Solution

We need to apply policer to limit the traffic. On Versa FlexVNF, a policer works in inbound direction. Policer action is configured on QoS profile (Step 1), further we need to associate this profile with a particular traffic flow using QoS policy rule (Step 3).

In this example we have 1 Gbps WAN link and we want to allow maximum 10Mbps of Internet traffic. So, here we need to configure 10Mbps policer on the “SD-WAN-traffic-profile” which is mapped with Customer traffic flow coming from LAN1 interface and going out on vni-0/0 interface (ptvi zone).

Topology

Configuration

1. Configure QoS Profile by logging into Versa Director
   Go to Appliance > Configuration> Class of Service> QoS Profiles and then click on + to create a new Profile.

We need to define Peak rate of internet traffic which needs to be allowed (i.e. 10Mbps ) and Burst size is in Byte [ 5000 Byte Default ]

Please Note: Burst size needs to be chosen carefully as it affects policer rate. Choosing burst size too large may cause policer to allow traffic more than the specified rate. Also choosing burst size too low may result in early drops than the specified rate. 

2. Configure QoS-policy
   Navigate to Appliance > Configuration > Class of Service> QoS Policies and then click on + button.
   There can be only one QoS-policy. By-default, there is ‘Default-policy’ configured so we can just delete the default one and create new policy with different name.

3. Configure QoS policy rules
   Now navigate to Appliance > Configuration > Class of Service> QoS Policies> Rules and then click on + to create new rule.

Match source and destination zones. Here source zone is “Intf-LAN1-Zone” where SD-WAN traffic is coming.

As the SDWAN traffic traverses out of tunnel interface, we need to select “ptvi“ as destination zone.

We can match other parameters as well based on requirement.

4. Finally, in enforce tab we need to associate the rule with QoS profile created in step1 above and then click OK to complete the configuration.

Verification

Initiate the traffic and check if configured qos-policy getting hits. If the qos policy rule is not getting hits, then cross check source/destination parameters.

admin@CPE1-cli> show orgs org-services AGR class-of-service qos-policies AGR-QoS-Policy rules qos-policy-stats SD_WAN-limit

                     QOS               QOS      QOS       QOS      PPS      PPS      KBPS     KBPS     

              QOS    DROP    QOS DROP  FORWARD  FORWARD   SESSION  POLICER  POLICER  POLICER  POLICER  

              HIT    PACKET  BYTE      PACKET   BYTE      DENY     PKTS     BYTES    PKTS     BYTES    

RULE NAME     COUNT  COUNT   COUNT     COUNT    COUNT     COUNT    DROPPED  DROPPED  DROPPED  DROPPED  

--------------------------------------------------------------------------------------------------------

SD_WAN-limit  7      49505   41683210  12911    10854954  0        0        0        49505    41683210  <<< Drops due to policer

vsm-vcsn0> show vsm statistics dropped

DPDK ERROR STATISTICS

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DATAPATH ERROR STATISTICS

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# Packets Dropped - Filter Lookup Module Action Denied : 10

THRM ERROR STATISTICS

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NFP ERROR STATISTICS

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# Dropped Anchor rate limiting             : 102 <<< Drops due to policer

VSF ERROR STATISTICS

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VUNET ERROR STATISTICS

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COS DROPS

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# Shaper drops                             : 0