ASK THE EXPERTS - CISCO WIDE AREA APPLICATION SERVICES

[ciscomoderator]

Welcome to the Cisco Networking Professionals Ask the Expert conversation. This is an opportunity to learn how to configure and trouble shoot Cisco Wide Area Application Services with Mike Korenbaum and Smita Nambiar. Mike is a network consulting engineer for the Cisco Wide Area Application Services (WAAS) Planning, Design and Implementation Help Desk. He has been with Cisco for four years, three of which were spent supporting Application Networking Services products in the Cisco Technical Assistance Center. His area of expertise include product configuration, support, and design for Cisco's major application network products.

Smita is a network consulting engineer with the Cisco Wide Area Application Services (WAAS) Planning, Design and Implementation team.  She has been with Cisco for more than four years, starting as a customer support engineer for the Application Networking Services team in the Cisco Technical Assistance Center. Her area of expertise include design, implementation, and troubleshooting for Cisco's major application network products.

Remember to use the rating system to let Mike and Smita know if you have received an adequate response.

They might not be able to answer each question due to the volume expected during this event. Our moderators will post many of the unanswered questions in other discussion forums shortly after the event. This event lasts through July 30, 2010. Visit this forum often to view responses to your questions and the questions of other community members.

[smnambia]

As you are seeing the message

Disk based software not installed.
Some applications may not run correctly!

You will need to run the rescue(recovery) cd on this wae device and rebuild the device.

When you do this you will loose all disk information.

Following is the link on how to use the recovery cd

http://www.cisco.com/en/US/docs/app_ntwk_services/waas/waas/v421/configuration/guide/maint.html#wp1173532

Following is the link to download the recovery cd iso image

http://tools.cisco.com/support/downloads/go/ImageList.x?relVer=4.1.7&mdfid=280484571&sftType=Wide+Area+Application+Services+%28WAAS%29+Software&optPlat=&nodecount=10&edesignator=null&modelName=Cisco+Wide+Area+Application+Services+%28WAAS%29+Software&...

You will need to login(using your cco account) to download the iso image. Depending on what wae software you will need on that device please download that particular iso image.

Make sure you follow the sequence options mentioned in the documentation while running the recovery image.

Thanks

-Smita

[andrew.andy316]

Thanks Smita, will try that and get back to you.

[pokwan]

Hi,

Can you please advise how do I resolve TFO overload?

Thanks.

PF

sh tfo status
  Optimization Status:
     Configured: optimize full
     Current: no optimization, TFO Overloaded

  This device's ID:  00:14:5e:95:22:85

  TFO is up since Thu Jul  2 08:32:51 2009

  TFO is in overload state due to:
              Max connections
  Total number of entries into overload state since start: 2
  Time of last entry into overload state:                  Fri Jul 16 05:31:49 2010

[Jan Rockstedt]

Cisco WAAS Troubleshooting Guide for Release 4.1.3 and Later -- Troubleshooting Overload Conditions

http://docwiki.cisco.com/wiki/Cisco_WAAS_Troubleshooting_Guide_for_Release_4.1.3_and_Later_--_Troubleshooting_Overload_Conditions

[pokwan]

Thanks Jan

[Michael Korenbaum]

Hi,

As Jan pointed out by referencing the WAAS Troubleshooting Wiki, there is nothing you can do from a configuration standpoint to resolve a TFO overload condition. 

According to the output you provided your WAE has reached its connection limit.  The only way to come out of this condition is for a number of connections to be closed by the clients/servers, thereby reducing the number of concurrent optimized connections handled by this WAE.  Once the WAE drops below its connection limit threshold the alarm will clear and new TCP sessions will be optimized.  Note, while in a TFO overload condition all new TCP sessions will be placed in pass through (e.g. not optimized).

What device model is this and does it have a memory upgrade?

How many users/computers are at this site?

Is this an edge site or a data center site?

Cheers,

Mike

[wrobbin]

Also do you optimze the Cisco Default package or have you added your own classifers? only a few options there

1. Upgrade Memory

2. Get a bigger box

3. Reduce what type of traffic you are optimizing.

there a prob a few other but those are the one i can think of right now

[pokwan]

Hi,

Thanks.

We optimize CISCO default package.

PF

[pokwan]

Mike,

Thanks.

The model is WAE-512-K9, no memory upgrade

There is about 80 users.

It is an edge device

Thanks.

PF

[Michael Korenbaum]

PF,

A WAE-512 with 1GB of memory (the default), can support up to 600 concurrent optimized TCP sessions.  As a general guide when sizing a WAAS appliance we assume 10 concurrent TCP sessions per user.  Since you have 80 users, that puts you around 800 concurrent TCP sessions, which is why you are seeing TFO overload due to max connections.

If you device is constantly in and out of overload due to max connections I would think this edge site is undersized, and you may want think about adding a second WAE or upgrading this site to new WAE that can handle more connections.

When deciding on expanding or implementing a WAAS network I'd suggest you consult the WAAS sizing tool here:

http://tools.cisco.com/WAAS/sizing/

Cheers,

Mike

[pokwan]

Mike,

Thanks very much for your help. It is much appreciated.

PF

[wrobbin]

How would I implement a Secondary Central Manager in to an already existing WAAS infrastructure?

[Michael Korenbaum]

Hi,

You can implement a WAE as a secondary/warm standby CM by following the instructions outlined here:

http://www.cisco.com/en/US/docs/app_ntwk_services/waas/waas/v421/configuration/guide/maint.html#wp1159476

Cheers,

Mike

[DARYLE DIANIS]

Is there any way to avoid negative compression?  When I drill down on some of my TCP connections, I see good, actually, great READ compression, but 'negative' compression on WRITEs.  Can I exclude WRITE traffic somehow in the policy?

[smnambia]

There is no way to disable just the write compression.You can disable the LZ compression entirely

If you are seeing this issue for a particular application,that has compression enabled then what you could do is have a custom policy for this  application and in the Action,instead of choosing Full optimization you can try the other options

TFO only

or

TFO+DRE

or

TFO+LZ

and check if this helps that application to avoid the negative write compression.

Could you also share the output for a particular tcp connection where you see good read vs write compression from both the wae's?

Also are you seeing this for particular application,then please do let us know the application name and version being used.

Thanks

-Smita