Cisco Nexus 5000 Series User manual

Send documentation comments to [email protected]
iii
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Preface
This preface describes the audience, organization, and conventions of the Cisco Nexus 5000
Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1). It also provides
information on how to obtain related documentation.
This chapter includes the following topics:
•Audience, page iii
•Document Conventions, page iii
•Related Documentation, page v
•Obtaining Documentation and Submitting a Service Request, page v
Audience
This publication is for experienced network administrators who configure and maintain Cisco NX-OS
on Cisco Nexus 5000 Platform switches and Cisco Nexus 5500 Platform switches.
Document Conventions
Command descriptions use the following conventions:
Convention Description
bold Bold text indicates the commands and keywords
that you enter literally as shown.
Italic Italic text indicates arguments for which the user
supplies the values.
[x] Square brackets enclose an optional
element(keyword or argument).
[x | y] Square brackets enclosing keywords or arguments
separated by a vertical bar indicate an optional
choice.
{x | y} Braces enclosing keywords or arguments
separated by a vertical bar indicate a required
choice.

Send documentation comments to [email protected]
iv
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Preface
Screen examples use the following conventions::
Note Means reader take note. Notes contain helpful suggestions or references to material not covered in the
manual.
Caution Means reader be careful. In this situation, you might do something that could result in equipment
damage or loss of data.
[x {y | z}] Nested set of square brackets or braces indicate
optional or required choices within optional or
required elements. Braces and a vertical bar within
square brackets indicate a required choice within
an optional element.
variable Indicates a variable for which you supply values,
in context where italics cannot be used.
string A nonquoted set of characters. Do not use
quotation marks around the string or the string will
include the quotation marks.
Convention Description
screen font Terminal sessions and information the switch
displays are in screen font.
boldface screen font Information you must enter is in boldface screen
font.
italic screen font Arguments for which you supply values are in
italic screen font.
< > Nonprinting characters, such as passwords, are in
angle brackets.
[ ] Default responses to system prompts are in square
brackets.
!, # An exclamation point (!) or a pound sign (#) at the
beginning of a line of code indicates a comment
line.

Send documentation comments to [email protected]
v
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Preface
Related Documentation
Documentation for Cisco Nexus 5000 Series Switches and Cisco Nexus 2000 Series Fabric Extenders is
available at the following URL:
http://www.cisco.com/en/US/products/ps9670/tsd_products_support_series_home.html
Obtaining Documentation and Submitting a Service Request
For information on obtaining documentation, submitting a service request, and gathering additional
information, see the monthly What’s New in Cisco Product Documentation, which also lists all new and
revised Cisco technical documentation:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html
Subscribe to the What’s New in Cisco Product Documentation as an RSS feed and set content to be
delivered directly to your desktop using a reader application. The RSS feeds are a free service. Cisco currently
supports RSS Version 2.0.

Send documentation comments to [email protected]
vi
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Preface

CHAPTER
Send documentation comments to [email protected]
1-1
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
1
Virtual Port Channel Operations
This chapter describes the best practices and operational procedures for the virtual port channel (vPC)
feature on Cisco Nexus 5000 Series switches that run Cisco NX-OS Release 5.0(2)N2(1) and earlier
releases.
This chapter includes the following sections:
•Information About vPC Operations, page 1-1
•vPC Consistency Checks, page 1-1
•Configuring Changes in vPC Topologies, page 1-9
•Replacing a Cisco Nexus 5000 Series Switch or Cisco Nexus 2000 Fabric Extender, page 1-10
•vPC Failure Recovery, page 1-14
•Tracing Traffic Flow in a vPC Topology, page 1-18
Information About vPC Operations
A vPC allows links that are physically connected to two different Cisco Nexus 5000 Series switches to
appear as a single port channel to a third switch. The third switch can be a Cisco Nexus 2000 Series
Fabric Extender or a switch, server, or any other networking device. A vPC can provide Layer 2
multipath capability which allows you to create redundancy by increasing bandwidth, enabling multiple
parallel paths between nodes, and load-balancing traffic where alternative paths exist.
For a quick overview of vPC configurations, see the Virtual PortChannel Quick Configuration Guide at
the following URL:
http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/configuration_guide_c07-54356
3.html
vPC Consistency Checks
This section includes the following topics:
•Type 1 and Type 2 Consistency Check Parameters, page 1-2
•Graceful Consistency Check, page 1-3
•Configuring Per-VLAN Consistency Checks, page 1-5
•Identifying Inconsistent vPC Configurations, page 1-6

Send documentation comments to [email protected]
1-2
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
•Bypassing a vPC Consistency Check When a Peer Link is Lost, page 1-8
Type 1 and Type 2 Consistency Check Parameters
Before a Cisco Nexus 5000 Series switch brings up a vPC, the two Cisco Nexus 5000 Series switches in
the same vPC domain exchange configuration information to verify if both switches have compatible
configurations for a vPC topology. Depending on the severity of the impact of possible mismatched
configurations, some configuration parameters are considered as Type 1 consistency check parameters
while others are considered as Type 2.
When a mismatch in Type 1 parameters occur, the following applies:
•If a graceful consistency check is enabled (default), the primary switch keeps the vPC up while the
secondary switch brings it down
•If a graceful consistency check is disabled, both peer switches suspend VLANs on the vPC ports.
Note The graceful consistency check is a new feature introduced in Cisco NX-OS Release 5.0(2)N2(1) and is
enabled by default. For more details, see the “Graceful Consistency Check” section on page 1-3.
When Type 2 parameters exist, a configuration mismatch generates a warning syslog message. The vPC
on the Cisco Nexus 5000 Series switch remains up and running. The global configuration, such as
Spanning Tree Protocol (STP), and the interface-level configurations are included in the consistency
check.
The show vpc consistency-parameters global command lists all global consistency check parameters.
Beginning with Cisco NX-OS Release 5.0(2)N1(1), QoS parameters have been downgraded from Type
1 to Type 2.
This example shows how to display all global consistency check parameters:
switch# show vpc consistency-parameters global
Legend:
Type 1 : vPC will be suspended in case of mismatch
Name Type Local Value Peer Value
------------- ---- ---------------------- -----------------------
QoS 2 ([], [3], [], [], [], ([], [3], [], [], [],
[]) [])
Network QoS (MTU) 2 (1538, 2240, 0, 0, 0, (1538, 2240, 0, 0, 0,
0) 0)
Network Qos (Pause) 2 (T, F, F, F, F, F) (T, F, F, F, F, F)
Input Queuing (Bandwidth) 2 (50, 50, 0, 0, 0, 0) (50, 50, 0, 0, 0, 0)
Input Queuing (Absolute 2 (F, F, F, F, F, F) (F, F, F, F, F, F)
Priority)
Output Queuing (Bandwidth) 2 (50, 50, 0, 0, 0, 0) (50, 50, 0, 0, 0, 0)
Output Queuing (Absolute 2 (F, F, F, F, F, F) (F, F, F, F, F, F)
Priority)
STP Mode 1 MST MST
STP Disabled 1 None None
STP MST Region Name 1 "" ""
STP MST Region Revision 1 0 0
STP MST Region Instance to 1
VLAN Mapping
STP Loopguard 1 Disabled Disabled
STP Bridge Assurance 1 Enabled Enabled
STP Port Type, Edge 1 Normal, Enabled, Normal, Enabled,
BPDUFilter, Edge BPDUGuard Disabled Disabled
STP MST Simulate PVST 1 Enabled Enabled
Allowed VLANs - 1,10,100-101,200-201 1,10,100-101,200-201,2

Send documentation comments to [email protected]
1-3
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
000
Local suspended VLANs - - -
Use the show vpc consistency-parameters interface port-channel number command to display the
interface-level consistency parameters.
This example shows how to display the interface-level consistency parameters:
n5k-1# show vpc consistency-parameters interface port-channel 200
Legend:
Type 1 : vPC will be suspended in case of mismatch
Name Type Local Value Peer Value
------------- ---- ---------------------- -----------------------
STP Port Type 1 Default Default
STP Port Guard 1 None None
STP MST Simulate PVST 1 Default Default
lag-id 1 [(7f9b, [(7f9b,
0-23-4-ee-be-64, 80c8, 0-23-4-ee-be-64, 80c8,
0, 0), (8000, 0, 0), (8000,
0-1e-13-15-7-40, 1, 0, 0-1e-13-15-7-40, 1, 0,
0)] 0)]
mode 1 active active
Speed 1 10 Gb/s 10 Gb/s
Duplex 1 full full
Port Mode 1 trunk trunk
Native Vlan 1 1 1
Shut Lan 1 No No
Allowed VLANs - 1-999,1001-3967,4048-4 1-3967,4048-4093
093
The Cisco Nexus 5000 Series switch conducts vPC consistency checks when it attempts to bring up a
vPC or when you make a configuration change.
In the interface consistency parameters shown in the above output, all configurations except the Allowed
VLANs are considered as Type 1 consistency check parameters. The Allowed VLAN (under the trunk
interface) is considered as a Type 2 consistency check parameter. If the Allowed VLAN ranges are
different on both VLANs that means that only common VLANs are active and trunked for the vPC while
the remaining VLANs are suspended for this port channel.
Graceful Consistency Check
Beginning with Cisco NX-OS Release 5.0(2)N2(1) and later releases, when a Type 1 mismatch occurs,
by default, the primary vPC links are not suspended. Instead, the vPC remains up on the primary switch
and the Cisco Nexus 5000 Series switch performs Type 1 configurations without completely disrupting
the traffic flow. The secondary switch brings down its vPC until the inconsistency is cleared.
However, in Cisco NX-OS Release 5.0(2)N2(1) and earlier releases, this feature is not enabled for
dual-homed FEX ports. When Type-1 mismatches occur in this topology, the VLANs are suspended on
both switches. The traffic is disrupted on these ports for the duration of the inconsistency.
To minimize disruption, we recommend that you use the configuration synchronization feature for
making configuration changes on these ports.
To enable a graceful consistency check, use the graceful consistency-check command. Use the no form
of this command to disable the feature. The graceful consistency check feature is enabled by default.
This example shows how to enable a graceful consistency check:
switch(config)# vpc domain 10

Send documentation comments to [email protected]
1-4
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
switch(config-vpc-domain)# [no] graceful consistency-check
This example shows that the vPC ports are down on a secondary switch when an STP mode mismatch
occurs:
This example shows that the vPC ports and the VLANs remain up on the primary switch when an STP
mode mismatch occurs:
This example shows that the vPC ports are down on a secondary switch when an interface-level Type 1
inconsistency occurs:

Send documentation comments to [email protected]
1-5
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
This example shows that the vPC ports and the VLANs remain up on the primary switch when an
interface-level Type 1 inconsistency occurs:
Configuring Per-VLAN Consistency Checks
Beginning with Cisco NX-OS Release 5.0(2)N2(1), the Cisco Nexus 5000 Series switch performs
Type-1 consistency checks on a per-VLAN basis when you enable or disable STP on a VLAN. VLANs
that do not pass this consistency check are brought down on the primary and secondary switches while
other VLANs are not affected.
When you enter the no spanning-tree vlan number command on one peer switch, only the specified
VLAN is suspended on both peer switches; the other VLANs remain up.
Note Per-VLAN consistency checks are not dependent on whether graceful consistency checks are enabled.
This example shows the active VLANs before suspending a specified VLAN:

Send documentation comments to [email protected]
1-6
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
This example shows that VLAN 5 is suspended but the remaining VLANs are up:
Identifying Inconsistent vPC Configurations
The show vpc command displays the vPC status and the vPC consistency check result for the global
consistency check and the interface-specific consistency check.
This example shows the global vPC consistency check failed because of the mismatched Network QoS
configuration:
You can use the show vpc consistency-parameters global command to identify the configuration
difference between two vPC peer switches.
This example shows the global consistency check failed because the STP mode was configured
differently on the two vPC switches: