Recent high latency to my vpn provider that uses azure nodes.

Question

Hello, I started having issues recently with network latency to certain applications that I believe specifically use azure services. For instance my VPN has increased its latency by approximately +20-40ms on all azure nodes. Attached below displays the RTT which is the latency.

Which is very weird because when I look at other nodes that are hosted in Amsterdam by other cloud providers I get a lot less latency. Attached below.

So the obvious solution would be to use another node to connect directly. However, the main problem is I use my VPN to reduce my latency (yes it works because it gives a better route to the servers than my isp) in a video game which also happens to be hosted on azure. So previously I used to get approximately 50ms to the game servers hosted on azure and now I am at to 90ms on a good day and 120+ on a bad day. I called my isp and they said the issue was not on their side and refused to help any further.

So I ran a traceroute and I am not sure how to proceed any further to fix my issue. Please note that the latency never used be this high. Thank you.

Tracing route to 52.236.155.161 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  192.168.3.1
  2     1 ms    <1 ms    <1 ms  192.168.100.1
  3     9 ms     9 ms     9 ms  196.70.144.1
  4     8 ms     8 ms     9 ms  adsl-118-85-192-81.adsl2.iam.net.ma [81.192.85.118]
  5     9 ms     8 ms     8 ms  adsl-121-85-192-81.adsl2.iam.net.ma [81.192.85.121]
  6     8 ms     8 ms    16 ms  105.73.30.248
  7    11 ms    10 ms    10 ms  inwi.ier02.rba30.ntwk.msn.net [104.44.196.73]
  8    11 ms    11 ms    11 ms  ae20-0.ier01.rba30.ntwk.msn.net [104.44.40.175]
  9    67 ms    67 ms    67 ms  ae22-0.ear01.bio70.ntwk.msn.net [104.44.42.125]
 10    86 ms    86 ms    86 ms  be-20-0.ibr01.bio70.ntwk.msn.net [104.44.22.107]
 11    85 ms    85 ms    85 ms  be-7-0.ibr01.par30.ntwk.msn.net [104.44.29.152]
 12    85 ms    85 ms    85 ms  be-9-0.ibr02.pnq01.ntwk.msn.net [104.44.16.145]
 13    93 ms    86 ms    84 ms  ae102-0.icr02.ams30.ntwk.msn.net [104.44.22.216]
 14     *        *        *     Request timed out.
 15     *        *        *     Request timed out.
 16     *        *        *     Request timed out.
 17     *        *        *     Request timed out.
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21     *        *        *     Request timed out.
 22     *        *        *     Request timed out.
 23     *        *        *     Request timed out.
 24    84 ms    84 ms    84 ms  52.236.155.161

Trace complete.

Answer 1

Hello @MK

Thank you for posting this concern on this community space.

I have read your case scenario description and I would like to gather or share my 2 cents here below:

1-For instance, I have faced the same issue with latency as well. On the output, you will see that I have a P2S VPN and I found that the MTU value configured is not the standard which is 1500.

Adapter info below:

PPP adapter vnet-southcentralus-xxxxx-xxx-001:

   Connection-specific DNS Suffix  . :
   IPv4 Address. . . . . . . . . . . : 192.168.254.2
   Subnet Mask . . . . . . . . . . . : 255.255.255.255
   Default Gateway . . . . . . . . . :

2-Then, you can look at the MTU value:

3- As per public documentation, there is a default behavior that is relevant to know which is:

• All data packets will be fragmented at 1400 as MTU value permitted.
• If on TCP session is observed TCP-Out-of-Orders packets sequence, Port Reused behavior and so on... Well, they will be dropped.
• If you want to enhance or speed up your data session, you can either use an NVA (Network Virtual Appliance) or work on the MSS value on TCP sessions.
• You can modify the MTU value along the routing path.
• Please direct your self to the following URL: https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-tcpip-performance-tuning    
• You can change the listening ports and among others.
• Furthermore, review the MTU value at the OS level on your server/vm.
• Finally, you can reset the VPN gateway and get better results with your latency concern.

Looking forward to your feedback,

Cheers,

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