{"id":3730,"date":"2012-06-01T14:49:53","date_gmt":"2012-06-01T12:49:53","guid":{"rendered":"https:\/\/ingmarverheij.com\/?p=3730"},"modified":"2013-11-30T13:05:30","modified_gmt":"2013-11-30T12:05:30","slug":"powershell-query-cisco-catalyst-4500-flow-control-statistics","status":"publish","type":"post","link":"https:\/\/ingmarverheij.com\/en\/powershell-query-cisco-catalyst-4500-flow-control-statistics\/","title":{"rendered":"PowerShell: Query Cisco (Catalyst 4500) Flow Control statistics"},"content":{"rendered":"

Last week I attended E2EVC<\/a> in Vienna, a non-commercial,virtualization community Event, and attended a session of Sa\u0161a Ma\u0161i\u0107<\/a> about an issue he had at a customer. In short, the problems where caused by a switch that couldn\u2019t process IP packets because it overflowed, and therefore Ethernet flow control<\/a> temporarily stopped the transmission of some attached devices. Although I\u2019m no network expert I do know this might be a serious issue. After reading this article<\/a>, you might agree.<\/p>\n

If you\u2019re looking for the PowerShell script, scroll to the bottom.<\/em><\/p>\n

<\/h4>\n

RxPause and TxPause<\/h4>\n

This week I\u00a0 was asked to troubleshoot performance issues at a customer and got informed that the core switches (Cisco Catalyst 4500) might be over capacity. A quick look in the flow control statistics (# show flowcontrol<\/a>) indicated there where send numerous RxPause and TxPause packages, a sign Flow Control has been active.<\/p>\n

<\/p>\n

 <\/p>\n

Port       Send FlowControl  Receive FlowControl  RxPause TxPause\r\n           admin    oper     admin    oper\r\n---------  -------- -------- -------- --------    ------- -------\r\nGi1\/1      off      off      desired  on          0       0\r\nGi1\/2      off      off      desired  off         0       0\r\nGi2\/1      on       on       desired  on          0       0\r\nGi2\/2      on       on       desired  on          72982   0\r\nGi2\/3      on       on       desired  on          0       0\r\nGi2\/4      on       on       desired  on          0       0\r\n(...)\r\nPo1        Unsupp.  Unsupp.  desired  off         0       0\r\nPo2        Unsupp.  Unsupp.  desired  off         0       0\r\nPo3        Unsupp.  Unsupp.  desired  off         0       315\r\nPo4        Unsupp.  Unsupp.  desired  off         386006  12387\r\n(...)<\/pre>\n
Since the IOS (not to confuse with the OS on Apple devices) was recently upgraded the statistics where\u00a0 \u201cfresh\u201d. In order to troubleshoot I need to collect the metrics over a longer period from multiple (core) switches, I needed an automated solution.<\/p>\n
<\/h4>\n
SNMP<\/h4>\n
The easiest (and most obvious) method would be to use SNMP to query the statistics. I found it the \u201ceasiest\u201d way of finding the correct OID by \u201cwalking\u201d the values (querying all exposed values) and match it with the values I found in the terminal session (# show flowcontrol).. In short, it wasn\u2019t exposed.<\/p>\n
 <\/p>\n
PowerShell<\/h4>\n
I needed an automated solution that queried multiple switches and store to a file it so I can analyze the data later. Since it temporary I didn\u2019t find it necessary to store it in a SQL database, a comma-separated-file (CSV) would be just fine (if you need to store it in SQL, contact me).<\/p>\n
I\u2019ve localized the \u2018comma\u2019 in the comma-separated-file since this is different in some countries. A Dutch operating system for instance has a semicolon.<\/em><\/p>\n
The IOS on the core switches didn\u2019t have cryptography so I was unable to use SSH, therefore I used telnet to connect to the switches.<\/p>\n
 <\/p>\n
Download<\/h2>\n\n\tFlowControl.ps1<\/a>\n\n
 <\/p>\n
Usage<\/strong>: FlowControl.ps1 \u2013remoteHost [\u2013remotePort] [\u2013username] \u2013password\u00a0 [-enablePassword]\u00a0 [-timeout]<\/p>\n