Per-VLAN (SVI) counter feature on Nexus 3000 platform

Introduction

This article documents per-VLAN counter feature on Nexus 3000 platform

Problem

Per-VLAN counter is not shown on “show interface vlan <vlan ID>” on unified image Release 7.x

Nexus_3064# show interface vlan 1 counter

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Port                                 InOctets                      InUcastPkts

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Vlan1                                  --                                0

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Port                              InMcastPkts                      InBcastPkts

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Vlan1                                  --                                 --

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Port                                OutOctets                     OutUcastPkts

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Vlan1                                  --                                 --

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Port                             OutMcastPkts                     OutBcastPkts

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Vlan1                                  --                                 --

Solution

1. On Release 7.x, per-VLAN counter is NOT supported on Nexus 3000. This is because SVI TCAM carving support is NOT available on Nexus 3000 platform and on Release 7.x, SVI TCAM carving support is necessary for per-VLAN counter to function correctly. 

Note

Starting with Release 7.0(3)I2(1) and later releases, there is a single image for booting the Cisco Nexus 3000 Series platforms. The kickstart and system images are not required anymore. The single image binary now boots up on both Cisco Nexus 3000 and 3100 Series platforms and Cisco Nexus 9000 Series platforms.  And On Nexus 9000 platform, per-VLAN counter feature is acheived by carving a new TCAM region for SVI, such behaviour is inherited on Nexus 3000 platform, Therefore, from Release 7.0(3)I2(1), SVI TCAM carving support is necessary for per-VLAN counter to function correctly.

Please see below for the TCAM carving options of Nexus 3000 Series Platform, we can see that option "SVI" is NOT available:

Nexus_3064(config)# hardware profile tcam region ?

  arpacl       Configure tcam for arpacl region

  e-qos        Configure tcam for e-qos region

  e-racl       Configure tcam for e-racl region

  e-vacl       Configure tcam for e-vacl region

  ifacl        Configure tcam for ifacl region

  ipsg         Configure tcam for ipsg region

  ipv6-e-racl  Configure tcam for ipv6-e-racl region

  ipv6-pbr     Configure tcam for ipv6-pbr region

  ipv6-qos     Configure tcam for ipv6-qos region

  ipv6-racl    Configure tcam for ipv6-racl region

  ipv6-sup     Configure tcam for ipv6-sup region

  nat          Configure tcam for NAT region

  pbr          Configure tcam for pbr region

  qos          Configure tcam for qos region

  qoslbl       Configure tcam for qoslbl region

  racl         Configure tcam for racl region

  sup          Configure tcam for sup-tcam region

  vacl         Configure tcam for vacl region

2. Per-VLAN counter feature is supported on Release 5.x, and it is also supported from day one in Release 6.x 

On Release 5.x, it has a section clearly stating SVI and VLAN counters are supported:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3000/sw/release/503_u3_1/n3k_rel_notes_503_u3_1.html#wp414722  

3. Although per-VLAN counter is supported on both Release 5.x and Release 6.x, the support is limited. Please see below for the limitations:

• Not all multicast packets will be counted, known control plane multicast packets (e.g. OSPF, EIGRP Hello Message etc) are NOT counted as they are punted to the CPU using CoPP queues.
• The counter value shown under “In UnicastPackets” counts all packets (including Unicast, Multicast and Broadcast) ingressing on that particular Layer port.
• At the time when this article is written, there is no fix or workaround available for Nexus 3000 Series Platform, however,per-VLAN counter featurewill be supported without theabove-mentionedlimitations on Nexus 3100 Series Platform if TCAM is carved for SVI.