If running Lync Server 2010, Lync Server 2013 or Skype for Business Server 2015, and started noticing these in your Lync Server event log sometime between May and June of 2017, while at the same time people can’t share PowerPoints or do Whiteboards / Q&A…

Then you’ve fallen victim of a known issue with the May 2017 .NET Framework Security and Quality Rollup affecting the Web Conferencing Service.

Luckily, Microsoft detailed two workarounds, one involves getting a new Edge Internal cert, and another involved a registry change. Here’s the details:

https://support.microsoft.com/en-us/help/4023993/ls-data-mcu-events-41025-and-41026-are-constantly-generated-after-you-

TL;DR: When dual-homing, make sure both your NICs have the same link speed (1Gb, 10Gb). VMware’s E1000E is 1Gb, and VMXNET3 is 10Gb. Automatic metrics will prefer the 10Gb and that may cause the issue below….

After a power loss over the weekend, two Skype for Business Front-Ends were restarted and the RTCSRV service failed to start. A bit about these machines that’s relevant to the issue:

• Running Widnows Server 2012 R2 as VMware ESXi 5.5 guests.
• Collocated Mediation service.
• Dual-homed, with Data network as default gateway, and Voice network to talk to a Sonus SBC, with service usage limited to the specified addresses for Primary and PSTN in the topology.

Certificate stores were in good order, so KB2795828 did not apply.

Event ID’s seen in the log were LS User Services 32178:

Failed to sync data for Routing group {0FCDD1FD-39AF-502A-AECA-E702A5E8FC55} from backup store.
Cause: This may indicate a problem with connectivity to backup database or some unknown product issue.
Resolution:
Ensure that connectivity to backup database is proper. If the error persists, please contact product support with server traces.

LS User Services 30988:

Sending HTTP request failed. Server functionality will be affected if messages are failing consistently.

Sending the message to https://FE1.domain.org:444/LiveServer/Replication failed. IP Address is IPOFVOICENIC. Error code is 0x2EFD. Content-Type is application/replication+xml. Http Error Code is 0x0.
Cause: Network connectivity issues or an incorrectly configured certificate on the destination server. Check the eventlog description for more information.
Resolution:
Check the destination server to see that it is listening on the same URI and it has certificate configured for MTLS. Other reasons might be network connectivity issues between the two servers.

and User Services 32174:

Server startup is being delayed because fabric pool manager has not finished initial placement of users.

Currently waiting for routing group: {EF5151C7-B5E1-53B8-9F61-0CC90C82B9F6}.
Number of groups potentially not yet placed: 9.
Total number of groups: 9.

[…]

The issue ended up being different Adapter Type in VMware for both NICs. The primary NIC was set to E1000E, so 1Gb/s Max, and the Voice NIC, which was added after the server was deployed, was set to VMXNET 3, which runs at 10Gb/s regardless of uplink bandwidth from the host.

Turns out the Windows Automatic Metric was messing up interface preference here because it was setting the 10Gb/s NIC with an automatic lower metric.

Manually setting a lower metric for the Primary NIC and rebooting the server resolved the issue.

New features!

• Video Based Screen Sharing (VBSS) in meetings, enables much more efficient screen sharing with fluid motion (not the 2fps we’re used to in meetings.
• Multiple Emergency Numbers in a location policy, useful for universities that may have their own local emergency number in addition to 911
• Busy Options like Busy on Busy and Voicemail on Busy.

Get it here:

https://support.microsoft.com/en-us/kb/3061064

Ever wondered what a proper T.38 Fax over IP (FoIP) transmission looks like running through Wireshark? Maybe you’re troubleshooting a call flow, or never seen a T.38 capture. Below I’ll try to explain the call flow and steps to look out for when troubleshooting T.38 calls. Here’s an Outbound FAX call originating from a FXS port in a Cisco CUBE, and going towards Flowroute.

• Initial SIP INVITE and early media receipt (ringback). Note this is all RTP.
  
• SDP from the INVITE shows media offered is all voice (RTP)
  
• 183 Session in Progress, and we start sending media too (again, RTP). Later on comes the 200 OK, meaning the call was answered on the remote end.
  
• Things changing now… in-dialog (RE)INVITE from Cisco CUBE to SIP trunk… RTP and T.38 packets mixed because the remote end has not accepted our INVITE yet, but we start sending media either way.
  
• And the SDP of the new INVITE now shows all T.38 media now.
  
• Once we get the 200 OK from Flowroute, it’s all T.38 media both ways.
  
• Now the flow gets interesting, more Fax-ey. Wireshark will decode the HDLC data and show interesting bits here
  • TSI, is our Fax station number programmed in the machine.
    
  • DCS, our Fax machine communicates the capabilities, and starts training.
    
  • If we look inside the packet’s data, our DCS has a lot more information about our Fax machine’s settings and resolution
    
  • Then we get an FTT, means the remote end “Failed to Train”. Not usually a sign something is wrong, but more a capability mismatch. The remote fax may accept only lower baud rates, and will fail to train any higher. This is normal unless it’s the only response we get back from the remote end.
    
  • We see the same process of TSI, DCS and FTT until we hit the right baud rate… in our case it’s 9600… Once we get that, we receive a CFR.
    
  • Followed by a short training to sync-up and data (because we did long training before the CFR)
    
  • And our actual FAX data which will vary
    
  • At the end of the data, Wireshark reassembles the packets and tells us whether there was a loss or not. In our case, we’re good!
    
  • We send an EOP to signal the end of the transmission
    
  • The remote end does an MCF to acknowledge receipt (this is how your Fax machine knows the fax is “good” on the other end)
    
  • And then we send a DCN to logically hang up the HDLC stream, but we wait for the remote end…
    
  • Remote end hangs up the call… and we’re done…
    

And that was it. Many exchanges and training but in the end our page was sent over a SIP trunk, negotiating T.38, training with the remote fax machine at 9600 baud, and transmitting one page in about a minute.

Sophos UTM v9 comes with the tcpdump utility, which lets you run packet captures from the shell. This is great and all, but in order to look at those pcaps with Wireshark, you need to pipe to a file, copy the file, then run Wireshark against it. Annoying. All of it.

What if we could remotely capture packets over an SSH tunnel? YES… turns out it’s a bit tricky if you’re on Windows, and the authentication piece to get root access without having to do the loginuser first. How? Keep reading…

First, the necessary ingredients:

• Sophos UTM
• Wireshark (or your favorite pcap application)
• Putty suite (specifically Plink and PuttyGen)

To start, we’ll need to enable Shell Access, with public key authentication, and with Root access but only with SSH key.

We need to use PuttyGen to generate the key pair we’ll use for root authentication, so open it, Generate the key, then copy the Public Key into the Authorized Keys for root in the UTM, apply and save… and also Save private key to somewhere you’ll remember. We’ll need this for Plink.

There’s our new key…

Then run the actual magic using Plink. Take the following command as an example:

plink -ssh root@firewall.domain.com -i C:\ssh-priv.ppk “tcpdump -s 0 -U -n -w – not port 22 and not host 192.168.0.1” | “C:\Program Files\Wireshark\Wireshark.exe” -k -i –

Replace the SSH connection string for your actual firewall FQDN, the filename of ssh-priv.ppk for the location of your saved Private Key generated with PuttyGen, and the not host 192.168.0.1 with the IP address of the firewall from the interface you’re reaching it.

Wireshark will open and start showing packets. You can smile and jump now.

You can modify the tcpdump parameters to better match the capture, for example, using -i eth1 to capture a specific interface, or filter specific traffic… once you’re done, just close Wireshark and CTRL+C the command.

Note, if you’re doing this capture remotely over WAN or Internet, it will tunnel ALL packets over SSH, so it will take up a lot of bandwidth…

Have fun!!!

VMware’s Performance Best Practices mentions you should set power management in the BIOS to “OS Controlled Mode” or equivalent. This is so you can control power saving from the hypervisor itself. It’s very useful when you want to change these settings on the fly without having to reboot into the BIOS, similar to how Windows power profiles work.

But the “gotcha” here, which is also mentioned in the best practices documentation, is that the default Power Policy setting is set to Balanced, when you most likely want to set this to High Performance, as you’ll see later…

This makes it pretty awful for latency-sensitive workloads. In Balanced, your CPU sometimes has to scale up or down in the power states before it can process an instruction, and this adds latency. The difference can be clearly seen by looking at the CPU Ready (RDY%) metric. Here’s the difference changing to High Performance made in a single vCPU VM:

And here is a 4 vCPU VM running Exchange 2013

My VM’s felt “snappier” after the change. It’s hard to avoid speaking subjectively here, but click-to-action felt quicker. Maybe it’s in my head, but I feel those charts tell a different story.

The effect the “Balanced” power savings has on CPU Ready times is clear as day, though it’s mentioned that Balanced has minimal to no impact on performance. I have yet to do benchmarks to show how CPU Ready% affects real workloads, but at the very least, CPU instruction latency from a guest VM is dramatically decreased, which benefits those real-time workloads like Lync, Skype for Business or VoIP.