Application Acceleration
Highlighted
Application Acceleration

Compression and Acceleration issues

‎09-21-2011 10:17 AM

Hello,

 

We just deployed WXC for a customer (Hub and spoke topology with 10 remote sites and all in off path mode --- all sites are connected via VSAT - 128kbps links). Everything seems to be working fine now except I am not convinced with the compression and especially acceleration performance. I know from experience that the WXC could do a lot better. I however decided to study the flow diagnostics for different sites and found a few ‘errors’ that I need clarification on. Please note that most of the compression issues come from the exchange (2007) and a few other applications (about 3) while the others are working fine. The following errors are seen after magnifying the diagnostic flow of these applications on the hub and some spokes:

 

Flow diagnostics summary under General Flow

1) Compression status     Pass through – No assembler

2) Compression status     Pass through – Filter Applied

Flow Diagnostics – Network Sequence Caching Details

1) Saw Reliable Packet      FALSE

2) Configured for Destination     FALSE

3) Configured for App     FALSE

Flow Diagnostics – TCP Acceleration

1) SYN-ACK Error (compressor)     DC Not active

2) Duplicate SYN seen (Decompressor)     TRUE

3) Duplicate SYN-ACK seen (Compressor)     TRUE

 

These errors occurred randomly in the flow diagnostics especially for exchange e.g. Exchange sometimes displays the ---- ‘Application name     Exchange’ and ‘Compression status    Compressed – Defined App’ while the network sequence caching of that same flow might then give an error ‘Saw Reliable Packet      FALSE’. There are about three other apps that exhibit this random behaviour too.

Also, the TCP Acceleration errors occur for more applications. Some applications do not even show any acceleration in all the branches. In general, the acceleration of this particular deployment is very poor.

 

I would appreciate your explanation of these errors with any recommendations you can offer.

 

Also, two sites have been problematic since the deployment. A particular site keeps having issues with their core applications and exchange intermittently (applications stop working). Once the traffic re-direction (WCCP) to the WXC of this branch has been removed, everything starts working well. Please note that this also applies even after the tunnels between that site (spoke) and the HQ (hub) have been disabled. The other problematic site works very fine most times, as a matter of fact, it is the branch that gives the best compression and acceleration statistics when it’s up. The issue with that branch is that the exchange application stops working sometimes. There was a particular situation in which only one person could send mails in the branch while others could pull their mails but could not send. Traffic re-direction to the WXC of that site is usually removed by the customer (network administrator) to ensure it works, before we get in to monitor the situation.

What could be the cause of these problems for the two sites?

 

Lastly, I noticed before close of business today that I couldn’t access 9 out of the 10 remote WXC’s from the HQ (hub) via web UI. It gives the error ‘internet explorer cannot display the webpage’. This is very strange to me. I pinged the WXCs and default gateways of these sites and they all responded. I also monitored the links and everything seems okay. The compression and acceleration statistics of these sites can still be viewed from the HQ and everything seems normal except I can’t access them for configuration changes.

What do you think?

 

Thanks in anticipation of your swift response.

 

Femi

4 REPLIES 4
Highlighted
Application Acceleration

Re: Compression and Acceleration issues

‎09-21-2011 07:22 PM

 

Hi Femi,

 

I went through the problem description and i understand there are multiple issues faced on the network with the WXC's.

 

I would recommend you to open a JTAC case so that we can analyze the logs and will provide you a prompt solution.

 

- What is the WXC version on all the WXC devices?

 

- Are you using any customized Application Definitions for the Exchange traffic in the WXC ? If yes, please check if the Application Definitions are configured in a right way on all the WXC's.

 

- Are the messages sent from Exchange 2007 is enabled with Encryption?

 

- Please ensure the NSC and TCP acceleration is enabled for the WXC's globally. If its enabled in the Global configuration, please ensure its enabled for the Application individually as well.

 

- Mostly these Saw Reliable packet Error would be seen, when the WXC doesnt see the complete flow. (TCP 3 way handshake).

 

- Regarding the WCCP, we need to have a look at the configurations and the logs to make any comment on that.

 

- Regarding the issue, unable to access the Spoke GUI from the HQ. Was this working before and recently you are facing this issue or wasnt it working right from the first?

 

- Are you able to do a SSH session to the WXC from the PC from the HQ site? Can you open the GUI of the Spoke WXC from a machine in the Spoke site?

 

Please confirm these and i would suggest you to open a JTAC case, as this involves a lot of testing and analysis, which is beyond the scope of this forum.

 

Thanks,

Magesh S.

Juniper Networks

Advanced JTAC Engineer - WX/MFC

 

Highlighted
Application Acceleration

Re: Compression and Acceleration issues

‎09-22-2011 07:51 AM
Thanks Magesh.

I will open a case with JTAC as recommended asap.

But can we talk about the issue of not being able to log in?

WXOS - 5.7.7 was used across all branches and I can do an SSH session to the remote WXCs from a PC at the HQ but the GUI doesn't work.

There's noone at the remote locations to log tnto the WXC so I can't tell if it works from there.

We could access the GUI since the time of deployment (3 weeks ago), this problem just started yesterday.

Thanks in anticipation.

Femi.
Highlighted
Application Acceleration

Re: Compression and Acceleration issues

‎09-22-2011 09:51 PM

 

Hi Femi,

 

The GUI access is done on port 443.

 

As you confirmed, the SSH works from the HQ PC, it wouldnt be a network connectivity issue. Its something to do with access to port 443.

 

Please ensure if there are any firewalls rules in the network, which may block this. Please check the firewall settings on the HQ PC also.

 

Also please try accessing using different browsers. (Please check if there were any changes made in the network, as the GUI access was working earlier).

 

Also please confirm what is the Off-path mode in the HQ side. I'm sure its WCCP on the Spoke side.

 

Thanks,

Magesh S.

Juniper Networks

Advanced JTAC Engineer - WX/MFC

 

Highlighted
Application Acceleration

Re: Compression and Acceleration issues

‎09-22-2011 10:04 PM

 

Hi Femi,

 

In addition to the above , please confirm if the HTTPS Application is enabled for Compression or not in the HQ WXC and the Spoke WXC.

 

Thanks,

Magesh S.

Juniper Networks

Advanced JTAC Engineer - WX/MFC

 

Feedback