Cflowd is a flow analysis tool, used for analyzing Flexible NetFlow (FNF) traffic data. It monitors traffic flowing through Cisco vEdge devices in the overlay network and exports flow information to a collector, where it can be processed by an IP Flow Information Export (IPFIX) analyzer. For a traffic flow, Cflowd periodically sends template reports to flow collector. These reports contain information about the flows and the data is extracted from the payload of these reports.

You can create a Cflowd template that defines the location of Cflowd collectors, how often sets of sampled flows are sent to the collectors, and how often the template is sent to the collectors (on Cisco SD-WAN Controllers and on Cisco SD-WAN Manager). You can configure a maximum of four Cflowd collectors per Cisco vEdge device. To have a Cflowd template take effect, apply it with the appropriate data policy.

You must configure at least one Cflowd template, but it need not contain any parameters. With no parameters, the data flow cache on the nodes is managed using default settings, and no flow export occurs.

Cflowd traffic flow monitoring is equivalent to FNF.

The Cflowd software implements Cflowd version 10, as specified in RFC 7011 and RFC 7012. Cflowd version 10 is also called the IP Flow Information Export (IPFIX) protocol.

Cflowd performs 1:1 sampling. Information about all flows is aggregated in the Cflowd records; flows are not sampled. Cisco vEdge devices do not cache any of the records that are exported to a collector.

Note	NetFlow on Secure Internet Gateway (SIG) tunnels is not supported on Cisco vEdge devices.

Cflowd and SNMP Comparison

Cflowd monitors service side traffic. Cflowd mainly monitors traffic from LAN to WAN, WAN to LAN, LAN to LAN and DIA. If you use Cflowd and SNMP to monitor traffic of LAN interface (input or output), then packets and bytes should be similar. The difference of bytes in SNMP starts from L2 header, but Cflowd starts from L3 header. However, if we use Cflowd and SNMP to monitor traffic of WAN interface (input or output), then packets or bytes are unlikely to be the same. All the traffic of WAN interfaces is not service side traffic. For example, Cflowd does not monitor BFD traffic, but SNMP does. The packets or bytes of Cflowd and SNMP traffic are not the same.

This topic provides general procedures for configuring Cflowd traffic flow monitoring. You configure Cflowd traffic flow monitoring using the basic components of centralized data policy. Cflowd template and Cflowd in data policy are independent of each other.

To configure policy for Cflowd traffic flow monitoring, use the Cisco SD-WAN Manager policy configuration wizard. The wizard consists of four sequential screens that guide you through the process of creating and editing policy components:

1. Create Applications or Groups of Interest—Create lists that group together related items and that you call in the match or action components of a policy.

2. Configure Topology—Create the network structure to which the policy applies.

3. Configure Traffic Rules—Create the match and action conditions of a policy.

4. Apply Policies to Sites and VPNs—Associate policy with sites and VPNs in the overlay network.

In the first three policy configuration wizard screens, you are creating policy components or blocks. In the last screen, you are applying policy blocks to sites and VPNs in the overlay network.

For the Cflowd policy to take effect, you must activate the policy.

Step 1: Start the Policy Configuration Wizard

To start the policy configuration wizard:

1. In the Cisco SD-WAN Manager NMS, select the Configure > Policies screen. When you first open this screen, the Centralized Policy tab is selected by default.

2. Click Add Policy.

The policy configuration wizard opens, and the Create Applications or Groups of Interest screen is displayed.

Step 2: Create Applications or Groups of Interest

To create lists of applications or groups to use in Cflowd policy:

1. Create new lists as described in the following table:

   • Prefix

     1. In the left bar, click Prefix.

     2. Click New Prefix List.

     3. Enter a name for the list.

     4. In the Add Prefix field, enter one or more data prefixes separated by commas.

     5. Click Add.

   • Site

     1. In the left bar, click Site.

     2. Click New Site List.

     3. Enter a name for the list.

     4. In the Add Site field, enter one or more site IDs separated by commas.

     5. Click Add.

   • VPN

     1. In the left bar, click VPN.

     2. Click New VPN List.

     3. Enter a name for the list.

     4. In the Add VPN field, enter one or more VPN IDs separated by commas.

     5. Click Add.

2. Click Next to Configure Topology in the wizard. When you first open this screen, the Topology tab is selected by default.

Step 3: Configure the Network Topology

To configure the network topology:

In the Topology tab, create a network topology as described:

1. Hub and Spoke - Policy for a topology with one or more central hub sites and with spokes connected to a hub

   1. In the Add Topology drop-down, select Hub and Spoke.

   2. Enter a name for the hub-and-spoke policy.

   3. Enter a description for the policy.

   4. In the VPN List field, select the VPN list for the policy.

   5. In the left pane, click Add Hub and Spoke. A hub-and-spoke policy component containing the text string My Hub-and-Spoke is added in the left pane.

   6. Double-click the My Hub-and-Spoke text string, and enter a name for the policy component.

   7. In the right pane, add hub sites to the network topology:

      1. Click Add Hub Sites.

      2. In the Site List field, select a site list for the policy component.

      3. Click Add.

      4. Repeat Steps 7a, 7b, and 7c to add more hub sites to the policy component.

   8. In the right pane, add spoke sites to the network topology:

      1. Click Add Spoke Sites.

      2. In the Site List field, select a site list for the policy component.

      3. Click Add.

      4. Repeat Steps 8a, 8b, and 8c to add more spoke sites to the policy component.

   9. Repeat Steps 5 through 8 to add more components to the hub-and-spoke policy.

   10. Click Save Hub and Spoke Policy.

2. Mesh - Partial-mesh or full-mesh region

   1. In the Add Topology drop-down, select Mesh.

   2. Enter a name for the mesh region policy component.

   3. Enter a description for the mesh region policy component.

   4. In the VPN List field, select the VPN list for the policy.

   5. Click New Mesh Region.

   6. In the Mesh Region Name field, enter a name for the individual mesh region.

   7. In the Site List field, select one or more sites to include in the mesh region.

   8. Repeat Steps 5 through 7 to add more mesh regions to the policy.

   9. Click Save Mesh Region.

To use an existing topology:

1. In the Add Topology drop-down, click Import Existing Topology. The Import Existing Topology popup displays.

2. Select the type of topology.

3. In the Policy drop-down, select the name of the topology.

4. Click Import.

Click Next to move to Configure Traffic Rules in the wizard. When you first open this screen, the Application-Aware Routing tab is selected by default.

Step 4: Configure Traffic Rules

To configure traffic rules for Cflowd policy:

1. In the Application-Aware Routing bar, select the Cflowd tab.

2. Click the Add Policy drop-down.

3. Select Create New. The Add Cflowd Policy popup opens.

4. Configure timer parameters for the Cflowd template:

   1. In the Active Flow Timeout field, specify how long to collect a set of flows on which traffic is actively flowing, a value from 30 through 3,600 seconds. The default is 600 seconds (10 minutes).

   2. In the Inactive Flow Timeout field, specify how long to wait to send a set of sampled flows to a collector for a flow on which no traffic is flowing, a value from 1 through 3,600 seconds. The default is 60 seconds (1 minute).

   3. In the Flow Refresh Interval field, specify how often to send the Cflowd template record fields to the collector, a value from 60 through 86,400 seconds (1 minute through 1 day). The default is 90 seconds.

   4. In the Sampling Interval field, specify how many packets to wait before creating a new flow, a value from 1 through 65,536 seconds. While you can configure any integer value, the software rounds the value down to the nearest power of 2.

5. Click Add New Collector, and configure the location of the Cflowd collector. You can configure up to four collectors.

   1. In the VPN ID field, enter the number of the VPN in which the collector is located.

   2. In the IP Address field, enter the IP address of the collector.

   3. In the Port Number field, enter the collector port number. The default port is 4739.

   4. In the Transport Protocol drop-down, select the transport type to use to reach the collector, either TCP or UDP.

   5. In the Source Interface field, enter the name of the interface to use to send flows to the collector. It can be either a Gigabit Ethernet, a 10-Gigabit Ethernet interface (ge), or a loopback interface (loopback number).

6. Click Save Cflowd Policy.

7. Click Next to move to Apply Policies to Sites and VPNs in the wizard.

Step 5: Apply Policies to Sites and VPNs

To apply a policy block to sites and VPNs in the overlay network:

1. If you are already in the policy configuration wizard, skip to Step 6. Otherwise, in the Cisco SD-WAN Manager NMS, select the Configure > Policies screen. When you first open this screen, the Centralized Policy tab is selected by default.

2. Click Add Policy. The policy configuration wizard opens, and the Create Applications or Groups of Interest screen is displayed

3. Click Next. The Network Topology screen opens, and in the Topology bar, the Topology tab is selected by default.

4. Click Next. The Configure Traffic Rules screen opens, and in the Application-Aware Routing bar, the Application-Aware Routing tab is selected by default.

5. Click Next. The Apply Policies to Sites and VPNs screen opens.

6. In the Policy Name field, enter a name for the policy. This field is mandatory and can contain only uppercase and lowercase letters, the digits 0 through 9, hyphens (–), and underscores (_). It cannot contain spaces or any other characters.

7. In the Policy Description field, enter a description of the policy. It can contain up to 2048 characters. This field is mandatory, and it can contain any characters and spaces.

8. From the Topology bar, select the type of policy block. The table then lists policies that you have created for that type of policy block.

9. Click Add New Site List. Select one or more site lists, and click Add.

10. Click Preview to view the configured policy. The policy is displayed in CLI format.

11. Click Save Policy. The Configuration > Policies screen opens, and the policies table includes the newly created policy.

Step 6: Activate a Centralized Policy

Activating a Cflowd policy sends that policy to all connected Cisco Catalyst SD-WAN Controllers. To activate a Cflowd policy:

1. In the Cisco SD-WAN Manager NMS, select the Configure > Policies screen. When you first open this screen, the Centralized Policy tab is selected by default.

2. Select a policy.

3. Click the More Actions icon to the right of the row, and click Activate. The Activate Policy popup opens. It lists the IP addresses of the reachable Cisco Catalyst SD-WAN Controllers to which the policy is to be applied.

4. Click Activate.

For a centralized data policy to take effect, you must apply it to a list of sites in the overlay network:

vSmart(config)# apply-policy site-list list-name data-policy policy-name

To activate the Cflowd template, associate it with the data policy:

vSmart(config)# apply-policy cflowd-template template-name

For all data-policy policies that you apply with apply-policy commands, the site IDs across all the site lists must be unique. That is, the site lists must not contain overlapping site IDs. An example of overlapping site IDs are those in the two site lists site-list 1 site-id 1-100 and site-list 2 site-id 70-130. Here, sites 70 through 100 are in both lists. If you apply these two site lists to two different data-policy policies, the attempt to commit the configuration on the Cisco Catalyst SD-WAN Controller would fail.

The same type of restriction also applies to the following types of policies:

• Application-aware routing policy (app-route-policy)

• Centralized control policy (control-policy)

• Centralized data policy (data-policy)

You can, however, have overlapping site IDs for site lists that you apply for different types of policy. For example, the sites lists for control-policy and data-policy policies can have overlapping site IDs. So for the two example site lists above, site-list 1 site-id 1-100 and site-list 2 site-id 70-130, you could apply one to a control policy and the other to a data policy.

After you successfully activate the configuration by issuing a commit command, the Cisco Catalyst SD-WAN Controller pushes the data policy to the Cisco vEdge devices located in the specified sites. To view the policy as configured on the Cisco Catalyst SD-WAN Controller, use the show running-config command in the Cisco Catalyst SD-WAN Controller. To view the policy that has been pushed to the device, use the show policy from-vsmart command on the device.

To display the centralized data policy as configured on the Cisco Catalyst SD-WAN Controller, use the show running-config command:

vSmart# show running-config policy 
vSmart# show running-config apply-policy

Enable Cflowd Visibility on Cisco vEdge devices

You can enable Cflowd visibility directly on Cisco vEdge devices, without configuring a data policy, so that you can perform traffic-flow monitoring on traffic coming to the router from all VPNs in the LAN. To do this, configure Cflowd visiblity on the device:

Device(config)# policy flow-visibility 

To monitor the applications, use the show app cflowd flows and show app cflowd statistics commands on the device.

This topic shows a complete example of configuring traffic flow monitoring.

Configuration Steps

Enable Cflowd traffic monitoring with a centralized data policy, so all configuration is done on a Cisco Catalyst SD-WAN Controller. The following example procedure monitors all TCP traffic, sending it to a single collector:

1. Create a Cflowd template to define the location of the collector and to modify Cflowd timers.

   vsmart(config)# policy cflowd-template test-cflowd-template
   vsmart(config-cflowd-template-test-cflowd-template)# collector vpn 1 address 172.16.155.15 port 13322 transport transport_udp
   vsmart(config-cflowd-template-test-cflowd-template)# flow-inactive-timeout 60
   vsmart(config-cflowd-template-test-cflowd-template)# template-refresh 90

2. Create a list of VPNs whose traffic you want to monitor.

   
   vsmart(config)# policy lists vpn-list vpn_1 vpn 1

3. Create a list of sites to apply the data policy to.

   vsmart(config)# policy lists site-list cflowd-sites site-id 400,500,600

4. Configure the data policy.

   vsmart(config)# policy data-policy test-cflowd-policy
   vsmart(config-data-policy-test-cflowd-policy)# vpn-list vpn_1
   vsmart(config-vpn-list-vpn_1)# sequence 1
   vsmart(config-sequence-1)# match protocol 6
   vsmart(config-match)# exit
   vsmart(config-sequence-1)# action accept cflowd
   vsmart(config-action)# exit
   vsmart(config-sequence-1)# exit
   vsmart(config-vpn-list-vpn_1)# default-action accept

5. Apply the policy and the Cflowd template to sites in the overlay network.

   vsmart(config)# apply-policy site-list cflowd-sites data-policy test-cflowd-policy
   ​Device(config-site-list-cflowd-sites)# cflowd-template test-cflowd-template

6. Activate the data policy.

   vsmart(config-site-list-cflowd-sites)# validate
   Validation complete
   vsmart(config-site-list-cflowd-sites)# commit
   Commit complete.
   vsmart(config-site-list-cflowd-sites)# exit configuration-mode

Example Configuration

Here is a complete example of a Cflowd configuration:

vsmart(config)# show configuration
apply-policy
 site-list cflowd-sites
  data-policy     test-cflowd-policy
  cflowd-template test-cflowd-template
 !
!
policy
 data-policy test-cflowd-policy
  vpn-list vpn_1
   sequence 1
    match
     protocol 6
    !
    action accept
     cflowd
    !
   !
   default-action accept
  !
 !
 cflowd-template test-cflowd-template
  flow-inactive-timeout 60
  template-refresh      90
  collector vpn 1 address 192.168.0.1 protocol ipv4 port 13322 transport transport_udp
 !
 lists
  vpn-list vpn_1
   vpn 1
  !
  site-list cflowd-sites
   site-id 400,500,600
  !
 !
!

Verify Cflowd Configuration

To verify the Cflowd configuration after activating it on the Cisco Catalyst SD-WAN Controller, use the show running-config policy and show running-config apply-policy commands.

Device# show flow record sdwan_flow_record-xxx 

flow record sdwan_flow_record-1666223692122679:
  Description:        flow and application visibility records
  No. of users:       1
  Total field space:  102 bytes
  Fields:
    match ipv4 protocol
    match ipv4 source address
    match ipv4 destination address
    match transport source-port
    match transport destination-port
    match routing vrf service
    collect ipv4 dscp
    collect transport tcp flags
    collect interface input
    collect interface output
    collect counter bytes long
    collect counter packets long
    collect timestamp absolute first
    collect timestamp absolute last
    collect application name
    collect flow end-reason
    collect connection initiator
    collect overlay session id input
    collect overlay session id output
    collect connection id long
    collect drop cause id
    collect counter bytes sdwan dropped long
    collect sdwan sla-not-met
    collect sdwan preferred-color-not-met
    collect sdwan qos-queue-id
collect counter packets sdwan dropped long

flow record sdwan_flow_record_ipv6-1667963213662363:
  Description:        flow and application visibility records
  No. of users:       1
  Total field space:  125 bytes
  Fields:
    match ipv6 protocol
    match ipv6 source address
    match ipv6 destination address
    match transport source-port
    match transport destination-port
    match routing vrf service
    collect ipv6 dscp
    collect transport tcp flags
    collect interface input
    collect interface output
    collect counter bytes long
    collect counter packets long
    collect timestamp absolute first
    collect timestamp absolute last
    collect application name
    collect flow end-reason
    collect connection initiator
    collect overlay session id input
    collect overlay session id output
    collect connection id long
    collect drop cause id
    collect counter bytes sdwan dropped long
    collect sdwan sla-not-met
    collect sdwan preferred-color-not-met
    collect sdwan qos-queue-id
    collect counter packets sdwan dropped long

Device# show flow monitor sdwan_flow_monitor cache
Cache type: Normal (Platform cache)
Cache size: 128000
Current entries: 4
High Watermark: 5
Flows added: 6
Flows aged: 2
- Inactive timeout ( 10 secs) 2
IPV4 SOURCE ADDRESS: 10.20.24.110
IPV4 DESTINATION ADDRESS: 10.20.25.110
TRNS SOURCE PORT: 40254
TRNS DESTINATION PORT: 443
IP VPN ID: 1
IP PROTOCOL: 6
tcp flags: 0x02
interface input: Gi5
interface output: Gi1
counter bytes long: 3966871
counter packets long: 52886
timestamp abs first: 02:07:45.739
timestamp abs last: 02:08:01.840
flow end reason: Not determined
connection initiator: Initiator
interface overlay session id input: 0
interface overlay session id output: 4
connection connection id long: 0xD8F051F000203A22

Check the Flows

On the Cisco vEdge devices affected by the Cflowd data policy, various commands let you check the status of the Cflowd flows.

To display information about the flows themselves.

vEdge# show app cflowd flows       
                                                            TCP                                                                                        TIME    
                                 SRC    DEST         IP     CNTRL  ICMP             EGRESS  INGRESS  TOTAL  TOTAL  MIN  MAX                            TO      
VPN  SRC IP       DEST IP        PORT   PORT   DSCP  PROTO  BITS   OPCODE  NHOP IP  INTF    INTF     PKTS   BYTES  LEN  LEN  START TIME                EXPIRE  
---------------------------------------------------------------------------------------------------------------------------------------------------------------
1    10.20.24.15  172.16.155.15  46772  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:31:45 2014  3       
1    10.20.24.15  172.16.155.15  46773  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:31:50 2014  8       
1    10.20.24.15  172.16.155.15  46774  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:31:55 2014  13      
1    10.20.24.15  172.16.155.15  46775  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:00 2014  18      
1    10.20.24.15  172.16.155.15  46776  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:05 2014  23      
1    10.20.24.15  172.16.155.15  46777  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:10 2014  28      
1    10.20.24.15  172.16.155.15  46778  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:15 2014  33      
1    10.20.24.15  172.16.155.15  46779  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:19 2014  38      
1    10.20.24.15  172.16.155.15  46780  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:25 2014  43      
1    10.20.24.15  172.16.155.15  46781  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:30 2014  48      
1    10.20.24.15  172.16.155.15  46782  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:35 2014  53      
1    10.20.24.15  172.16.155.15  46783  13322  0     6      2      0       0.0.0.0  0       0        1      78     78   78   Wed Nov 19 12:32:40 2014  58 

To quickly get a count of the number of flows.

vEdge# show app cflowd flow-count
VPN  count  
------------
1    12 

To display flow statistics.

vEdge# show app cflowd statistics 

      data_packets             :      0 
      template_packets         :      0 
      total-packets            :      0 
      flow-refresh             :      123 
      flow-ageout              :      117 
      flow-end-detected        :      0 
      flow-end-forced          :      0 

The following commands show information about the Cflowd collectors and the Cflowd template information that is sent to the collector.

vEdge# show app cflowd collector 

VPN  COLLECTOR IP   COLLECTOR  CONNECTION            IPFIX    CONNECTION  TEMPLATE  DATA     
ID   ADDRESS        PORT       STATE       PROTOCOL  VERSION  RETRY       PACKETS   PACKETS  
---------------------------------------------------------------------------------------------
1    172.16.155.15  13322      false       TCP       10       133         0         0        

vEdge# show app cflowd template 
app cflowd template name test-cflowd-template
app cflowd template flow-active-timeout 30
app cflowd template flow-inactive-timeout 60
app cflowd template template-refresh 90

FNF IPv6 Configuration Example for IPv6 traffic

The following example shows the centralized policy configuration with Cflowd for IPv6 traffic:

policy
 data-policy _vpn_1_accept_cflowd_vpn_1
  vpn-list vpn_1
   sequence 102
    match
     source-ipv6      2001:DB8:0:/32
     destination-ipv6 2001:DB8:1:/32
    !
    action accept
     count  cflowd_ipv6_1187157291
     cflowd
    !
   !
   default-action accept
  !
 !
 cflowd-template cflowd_server
  flow-active-timeout   60
  flow-inactive-timeout 30
  protocol              ipv6   
 !
 lists
  vpn-list vpn_1
   vpn 1
  site-list vedge1
   site-id 500
  !

apply-policy
 site-list vedge1
  data-policy _vpn_1_accept_cflowd_vpn_1 all
  cflowd-template cflowd_server

FNF Export Spread Configuration Example

The following example shows the configuration for export spreading:

Device# show sdwan policy from-vsmart
from-vsmart cflowd-template cflowd
 flow-active-timeout    600
 flow-inactive-timeout  60
 template-refresh       60
 flow-sampling-interval 1
 protocol               ipv4
 customized-ipv4-record-fields
  no collect-tos
  no collect-dscp-output
 collector vpn 0 address 10.0.100.1 port 4739 transport transport_udp
  export-spread
   app-tables   20
   tloc-tables  10
   other-tables 5