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This product reached the end of support date on March 31, 2021.

Top retransmission-affected servers

henk_stobbe
DynaMight Pro
DynaMight Pro

Hi,

See below screen print, 10.118.36.11 is filtered out on AMD (vlan should not be visible), when I make a trace, like rcon tcpdump ip number is not traced.Is this normal,behavour? All different vlan statistics are visable on CAS,

KR Henk

12 REPLIES 12

henk_stobbe
DynaMight Pro
DynaMight Pro

The question is about the server showing in this screen as "top restransmission-effected server"

zbigniew_cybuls
Inactive

Hi Henk,

I don't quite get the point of your question. Traffic diagnostics doesn't refer to VLANs at any moment. What it does is purely showing potential source of problems with traffic quality. The screenshot shows an AMD that actually has no traffic quality issues with one minor exception - for four servers (as in the table) the AMD detected quite high retransmission rate. This is not a problem in general, as it happens in the networks. This table in the Traffic diagnostics page makes more sense when it's connected with a high level of packet duplicates, as explained under the table.

traffic-diagnostics-2016-03-08-11-13-59.png

I could help more if you were more specific and provided more detail than just one screenshot.

-Zeke

henk_stobbe
DynaMight Pro
DynaMight Pro

Zeke,

Thanks for replying,

first:

I want to show network team the issue using "real traffic" with retransmissions packets from the server.

Strange thing is that the server with all the retransmits can not be found with "rcon tcpdump" tool.

second:

This server is on a vlan filtered out on AMD, that should be no problem. But I noticed that filtered-out vlans on AMD, wil show in CAS with statistics. Is this expected behavoir?

KR Henk

zbigniew_cybuls
Inactive

Henk,

Yes, it seems a bit strange at first sight. AMD should have seen and report on the same data. I'll talk to developers whether this is a situation they'd would like to investigate.

Regarding the filtered out server seen on this report, this might be OK. What do you mean by filtering out? How and where did you filter out the VLAN with this server? Can you share your configuration settings or a screenshots that shows it?

Regards,

-Zeke

henk_stobbe
DynaMight Pro
DynaMight Pro

I started with version 12.0.x below vlan definitions made it work:

henk_stobbe
DynaMight Pro
DynaMight Pro

Upgrading to 12.4.x gave tons of duplicates, so I put a filter in AMD and issue was solved:

henk_stobbe
DynaMight Pro
DynaMight Pro

In CAS you can see, I think all, vlans:

wojciech_kurek
Inactive

Henk,

Not if I understand correctly - your concern is that the CAS displays data from particular VLANs, but you cannot capture packets from those VLANs using rcon tcpdump?

Are you using any filter for recording the capture? If yes, then you need to explicitly specify that you wish to capture VLAN packets in the filter.

So instead of using e.g.:

tcpdump 0 "/tmp/capture.pcap" "host 1.2.3.4"

You need to use:

tcpdump 0 "/tmp/capture.pcap" "vlan and host 1.2.3.4"

Wojtek.

zbigniew_cybuls
Inactive

Henk,

another advice -- I suggest you started using Smart Packet Capture rather than tcpdump. It has no such limitations as tcpdump does. In addition, soon it will become the only supported method of capturing traffic traces on AMD. Amongst other benefits -- traffic traces can be nicely sliced and diced with Trace Trimmer within CAS, so you don't have to use any 3rd party tools.

-Zeke

henk_stobbe
DynaMight Pro
DynaMight Pro

Zeke,

Are there any things you have to do to make Smart Packet Capture Work?

KR Henk

zbigniew_cybuls
Inactive

No, it works out of the box, assuming you have a license for SPC (aka Network Forensics). Once a trace file is captured, it's available in CAS (Tools > Packet data mining tasks). Then, when you expand a capture item, you can download it or open with Trace Trimmer.

henk_stobbe
DynaMight Pro
DynaMight Pro

Zeke,

Another mysterie solved, I was sure I have seen it work but that must have been on APM university.

As you have guest no license at my site. Thx for your support today,

KR Henk