Cisco Application Virtual Switch Troubleshooting Guide, Release 5.2(1)SV3(3.x)

Port Channel Overview

Port channels aggregate multiple physical interfaces into one logical interface to provide higher bandwidth, load balancing, and link redundancy.

Cisco AVS supports LACP, MAC pinning, and static port channels in standalone and virtual port channel (VPC) mode.

A port channel performs the following functions:

Increases the aggregate bandwidth on a link by distributing traffic among all links in the channel.
Maintains optimal bandwidth usage by load balancing across multiple links.
Provides high availability. If one link fails, its traffic is switched to the remaining links. Higher-level protocols are unaware of the failed link, although bandwidth is diminished. The MAC address tables are not affected by link failure.

Verifying Port Channels

Procedure

Step 1

Display the ports on the Cisco AVS by entering the following command:

vemcmd show port

Example:

# vemcmd show port
LTL   VSM Port Admin Link State Cause PC-LTL SGID ORG svcpath Type   Vem Port
21      Eth1/5    UP   UP   FWD     -   1039    0   0       0          vmnic4
22      Eth1/6    UP   UP   FWD     -   1039    0   0       0          vmnic5
23      Eth1/7    UP   UP   FWD     -   1039    0   0       0          vmnic6
24      Eth1/8    UP   UP   FWD     -   1039    0   0       0          vmnic7
49                UP   UP   FWD     -      0    0   0       0            vmk1
50                UP   UP   FWD     -      0    0   0                    vmk2
1039       Po1    UP   UP   FWD     -      0    0   0

Step 2

Verify that the uplinks are in the FWD state rather than the BLK state (or, in the case of Link Aggregation Control Protocol [LACP], that uplinks are not in the Suspended [s] state or the Individual [I] state).

Step 3

Gather information about the remote physical ports by completing the following steps:

(For directly connected hosts) Display information about each local target logic (LTL) number with physical ports (21 to 24 in the previous example) by entering the following command:

vemcmd show lldp ltl

Example:

# vemcmd show lldp 21 
Chassis Id = 7c:69:f6:df:e4:f2
Port Id = Eth1/2
Extras:
3topology/pod-1/protpaths-101-102/pathep-[esx56-vpc]

leaf2
topology/pod-1

Note

If the PNICs used are UCS VIC P81E, disable LLDP on them so that you can view LLDP neighbors on Cisco AVS.

For leaf switches connected to a Layer 2 cloud (either Cisco Nexus 5000 or fabric interconnect), enter the following command on the Cisco Nexus 5000 or fabric interconnect console:

show lldp neighbors interface <interface_id> detail

Note

For Cisco UCS Manager fabric interconnect nodes, you must connect to Cisco NX-OS.

Example:

AVS-N5K# show lldp neighbors interface ethernet 1/29 detail 
Capability codes:
  (R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device
  (W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other
Device ID            Local Intf      Hold-time  Capability  Port ID  

Chassis id: 5087.89d3.ce3f
Port id: Eth1/5
Local Port id: Eth1/29
Port Description: topology/pod-1/protpaths-105-106/pathep-[N5K-VPC1]
System Name: scale-leaf4
System Description: topology/pod-1/node-106
Time remaining: 100 seconds
System Capabilities: B, R
Enabled Capabilities: B, R
Management Address: 5087.89d3.ce3f
Vlan ID: not advertised

Total entries displayed: 1

Step 4

For each output above, note the remote physical port (Port Id; for example, Eth1/2 in substep a and Eth1/5 in substep b of the preceding step), the policy group (for example, esx56-vpc and N5K-VPC1), and the remote switch (leaf) name (leaf2 and scale-leaf4).

Note which physical port and policy group are associated with which leaf switch.

Step 5

Display VPC information by entering the following command on each leaf switch identified in Step 3a and Step 3b:

show vpc

Example:

leaf1# show vpc
Legend:
(*) - local vPC is down, forwarding via vPC peer-link

vPC domain id : 1 
Peer status : peer adjacency formed ok 
vPC keep-alive status : Disabled 
Configuration consistency status : success 
Per-vlan consistency status : success 
Type-2 inconsistency reason : Consistency Check Not Performed
vPC role : primary, operational secondary
Number of vPCs configured : 4 
Peer Gateway : Disabled
Dual-active excluded VLANs : -
Graceful Consistency Check : Enabled
Auto-recovery status : Enabled (timeout = 240 seconds)
Operational Layer3 Peer : Disabled

vPC Peer-link status
---------------------------------------------------------------------
id Port Status Active vlans 
-- ---- ------ --------------------------------------------------
1       up     - 

vPC status
----------------------------------------------------------------------
id  Port Status Consistency Reason  Active vlans
--  ---- ------ ----------- ------  ------------
1   Po3  up     success     success 4090 

2   Po1  up     success     success 4090 

3   Po4  up     success     success 4090 

343 Po2  down*  success     success -

Step 6

In the previous command result, on the leaf and intermittent Layer 2 switches, verify that the VPC status is success.

Step 7

On each leaf switch, enter the following command:

show vpc role

Example:

scale-leaf3# show vpc role

vPC Role status
----------------------------------------------------
vPC role                        : secondary                     
Dual Active Detection Status    : 0
vPC system-mac                  : 00:23:04:ee:be:02             
vPC system-priority             : 32667
vPC local system-mac            : 50:87:89:a2:53:59             
vPC local role-priority         : 106 
scale-leaf3#

scale-leaf4# show vpc role 

vPC Role status
----------------------------------------------------
vPC role                        : primary                       
Dual Active Detection Status    : 0
vPC system-mac                  : 00:23:04:ee:be:02             
vPC system-priority             : 32667
vPC local system-mac            : 50:87:89:d3:ce:71             
vPC local role-priority         : 105 
scale-leaf4#

Step 8

In the previous command result, verify that there is one primary and one secondary role per VPC, similar to the example in Step 7.

Step 9

On each leaf switch, display port channel information by entering the following command:

show port-channel summary

Example:

leaf1# show port-channel summary 
Flags:  D - Down        P - Up in port-channel (members)
        I - Individual  H - Hot-standby (LACP only)
        s - Suspended   r - Module-removed
        S - Switched    R - Routed
        U - Up (port-channel)
        M - Not in use. Min-links not met
--------------------------------------------------------------------------------
Group Port-       Type     Protocol  Member Ports
      Channel
--------------------------------------------------------------------------------
1     Po1(SU)     Eth      LACP      Eth1/1(P)    Eth1/2(P)    
2     Po2(SU)     Eth      LACP      Eth1/19(P)   Eth1/20(P)   
3     Po3(SU)     Eth      LACP      Eth1/33(P)   
4     Po4(SU)     Eth      LACP      Eth1/34(P)   
leaf1#

Step 10

In the previous command result, verify that the protocol and the status of each member port (the flag, in parentheses after the port name) are correct for the port channel type:


Port Channel Type	Protocol	Status Flag
static	NONE	P
LACP	LACP	P
MACPIN	LACP	I

Any other protocol or status value indicates a configuration problem.

Note

LACP automatically negotiates both ends of the port channel configuration, so correct protocol and status indicate success. For static and MAC pinning port channels, it is possible to have a misconfiguration and still show the correct protocol and status. The SD (Down) status is the expected behavior for a port channel with MAC pinning.

The remaining steps describe how to identify misconfigured port channels.

Step 11

Compare the outputs of the vemcmd show lldpltl (Step 4) and show port-channel summary commands (Step 9). The outputs should show the same physical ports for a given leaf.

Step 12

If you find misplaced physical ports in the diagnostic steps above, log in to the Cisco Application Centric Infrastructure (APIC) GUI and fix them, as follows:

Go to Fabric > Access Policies > Interface Profiles > Policy Groups. Find the profile corresponding to the policy groups found in the vemcmd show lldpltl command.
Go to Fabric > Access Policies > Interface Profiles > Profiles.
For each profile that corresponds to the policy group identified above, change the configuration so that the policy reflects the actual port configuration.

Alternatively, you can fix the misconfiguration by changing the physical port connections to agree with the connections that are specified in the profile.

Troubleshooting Port Channel Creation

If port channel creation fails, you might have configured too many port channels or port channel members.

Procedure

If necessary, reconfigure your system to require only eight port channel members.

Only eight uplinks are supported on one system. Only one port channel is supported on one system.

Book Title

Chapter Title

Results

Chapter: Port Channels

Port Channels

Port Channel Overview

Verifying Port Channels

Procedure

Example:

Example:

Example:

Example:

Example:

Example:

Troubleshooting Port Channel Creation

Procedure

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