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Jonnie1

MTU on your servers

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Notice the difference in MSS, MTU and TCP Window with Malwarebytes Privacy off and then with it turned on.
My router and PC Network adapters MTU is set for 1500 by default.

Does the fact that the servers Malwarebytes Privacy connect to have an MTU of 1420 affect the performance of the connection? Is there a reason your servers are using a different size MTU?


Malwarebytes Privacy off:
« SpeedGuide.net TCP Analyzer Results »
Tested on: 2020.05.08 08:30
IP address: 173.81.xxx.xx
Client OS/browser: Windows 10 (Internet Explorer 11.0)
 TCP options string: 020405b40303090402000000
MSS: 1460
MTU: 1500

TCP Window: 524288 (not multiple of MSS)
RWIN Scaling: 9 bits (2^9=512)
Unscaled RWIN : 1024
Recommended RWINs: 64240, 128480, 256960, 513920, 1027840
BDP limit (200ms): 20972kbps (2621KBytes/s)
BDP limit (500ms): 8389kbps (1049KBytes/s)
MTU Discovery: ON
TTL: 52
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

Malwarebytes Privacy on:
« SpeedGuide.net TCP Analyzer Results »
Tested on: 2020.05.08 08:32
IP address: 86.106.xxx.xxx
Client OS/browser: Windows 10 (Internet Explorer 11.0)
 TCP options string: 020405640103030801010402
MSS: 1380
MTU: 1420
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput. If you are using a router, it could be limiting your MTU regardless of Registry settings.

TCP Window: 262144 (not multiple of MSS)
RWIN Scaling: 8 bits (2^8=256)
Unscaled RWIN : 1024
Recommended RWINs: 63480, 126960, 253920, 507840, 1015680
BDP limit (200ms): 10486kbps (1311KBytes/s)
BDP limit (500ms): 4194kbps (524KBytes/s)
MTU Discovery: ON
TTL: 52
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)
 

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VPN is a pipe much like the Point to Point Protocol over Ethernet (PPPoE) and introduces overhead.  With PPPoE the overhead is 8 bytes while the VPN is 80 bytes reducing the MTU to 1420.

This article from SonicWall gives some information and a comparison.

https://www.sonicwall.com/support/knowledge-base/set-mtu-in-vpn-environment-in-case-of-throughput-issues/170705131319789/

 

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21 minutes ago, David H. Lipman said:

VPN is a pipe much like the Point to Point Protocol over Ethernet (PPPoE) and introduces overhead.  With PPPoE the overhead is 8 bytes while the VPN is 80 bytes reducing the MTU to 1420.

This article from SonicWall gives some information and a comparison.

https://www.sonicwall.com/support/knowledge-base/set-mtu-in-vpn-environment-in-case-of-throughput-issues/170705131319789/

 

Thanks for the feedback. I think I will just keep it simple and not be concerned about as everything works just fine. Just curious.

You know what they say about the curious cat.:wacko:

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