sflow configuration Cisco Nexus 9396PQ

Question

We have Cisco a Nexus switch with M12PQ 12x40G GEM expansion card. Today when i enabled sflow on one of 40G interface i got following error:

# sflow data-source interface e2/12
In order to enable sFlow sampling on North star front panel port(Ethernet2/12), please either carve both span and sflow tcam regions with non-zero sizes using the commands
'hardware access-list tcam region span <size>'
'hardware access-list tcam region sflow <size>'
or remove both span and sflow tcam regions and carve a span-sflow tcam region with a non-zero size using the commands 

I found this article related that: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/system_management/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_System_Management_Configuration_Guide_7x/b_Cisco_Nexus_9000_Series_NX-OS_System_Management_Configuration_Guide_7x_chapter_011000.pdf

my current usage of tcam look like following:

# show hardware access-list resource utilization

slot  1
=======



INSTANCE 0x0
-------------


         ACL Hardware Resource Utilization (Mod 1)
         ----------------------------------------------------------
                                        Used    Free    Percent
                                                        Utilization
-------------------------------------------------------------------
Ingress IPv4 PACL                       3       509     0.59
Ingress IPv4 Port QoS                   4       252     1.56
Ingress IPv4 VACL                       2       510     0.39
Ingress IPv4 RACL                       221     291     43.16
Egress IPv4 VACL                        3       509     0.59
Egress IPv4 RACL                        3       253     1.17
SUP COPP                                205     51      80.08
SUP COPP Reason Code TCAM               6       122     4.69
Redirect                                2       510     0.39
SPAN                                    21      235     8.20
VPC Convergence                         1       255     0.39

LOU                                     2       22      8.33
Both LOU Operands                       2
Single LOU Operands                     0
LOU L4 src port:                        1
LOU L4 dst port:                        1
LOU L3 packet len:                      0
LOU IP tos:                             0
LOU IP dscp:                            0
LOU ip precedence:                      0
LOU ip TTL:                             0
TCP Flags                               0       16      0.00

Protocol CAM                            2       244     0.81
Mac Etype/Proto CAM                     0       14      0.00

L4 op labels, Tcam 0                    0       1023    0.00
L4 op labels, Tcam 2                    1       62      1.58
L4 op labels, Tcam 6                    0       2047    0.00

Ingress Dest info table                 0       512     0.00
Egress Dest info table                  0       512     0.00


INSTANCE 0x1
-------------


         ACL Hardware Resource Utilization (Mod 1)
         ----------------------------------------------------------
                                        Used    Free    Percent
                                                        Utilization
-------------------------------------------------------------------
Ingress NS IPv4 Port QoS                1       255     0.39
Ingress NS IPv4 L3 QoS                  1       255     0.39
Ingress NS IPv4 VLAN QoS                1       255     0.39

LOU                                     0       24      0.00
Both LOU Operands                       0
Single LOU Operands                     0
LOU L4 src port:                        0
LOU L4 dst port:                        0
LOU L3 packet len:                      0
LOU IP tos:                             0
LOU IP dscp:                            0
LOU ip precedence:                      0
LOU ip TTL:                             0
TCP Flags                               0       16      0.00

Protocol CAM                            0       246     0.00
Mac Etype/Proto CAM                     0       14      0.00

L4 op labels, Tcam 0                    0       7       0.00
L4 op labels, Tcam 2                    0       7       0.00
L4 op labels, Tcam 6                    0       2047    0.00

Ingress Dest info table                 0       512     0.00
Egress Dest info table                  0       512     0.00

Now question is, why am I not seeing any span or sflow region in above output and what are the options i have here to make it work?

Answer 1

#Solution

In this platform sflow has default zero 0 tcam slice allocated

sFlow TCAM size

# show hardware access-list tcam region | grep "sFlow ACL"
                               sFlow ACL [sflow] size =    0
                     SPAN+sFlow ACL [span-sflow] size =    0

Span TCAM size

# show hardware access-list tcam region | grep "SPAN"
                                     SPAN [span] size =  256
                     SPAN+sFlow ACL [span-sflow] size =    0

If you have no plan to use SPAN port then you can take 256 slice from span and give it to sflow.

# hardware access-list tcam region span 0
# hardware access-list tcam region sflow 256

After Reload/reboot of switch you can see following result

# show hardware access-list tcam region | grep -i sflow
                               sFlow ACL [sflow] size =  256
                     SPAN+sFlow ACL [span-sflow] size =    0

Now you are ready to use sFlow