ip tcp mss-adjust

InSearchOf
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I have a question on ip tcp mss-adjust. We have about 12 site to site ipsec tunnels configured on our VPN router. I noticed on the VPN router that has all the tunnels configured at the main location it has "ip tcp mss-adjust 1400" on the outbound interface but when I look at the routers at the remote locations I do not see the "ip tcp mss-adjust" configured on any interface. Shouldn't I have this configured on every router? And if so, on which interface should I have it on?
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Network Architect
Commented:
Once the packet size has been throttled down, it should stay at that size.  You shouldn't have to configure that everywhere.  You may want to look at the device on the other end of the tunnel to make sure it's doing the same thing.  But if you're not experiencing connection timeouts, you may not need it.
InSearchOfIT Director

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Commented:
Well, I have configured on the main VPN router which has all the VPN tunnels configured. I do experience timeouts and latency at the remote sites which do not have that setting configured.
Personally I would recommended to set the 'ip tcp mss-adjust' at both ends of a tunnel because then you are changing the MSS for the TCP connection when it is set up before it goes over the tunnel no matter which end initiates the connection.
InSearchOfIT Director

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Commented:
Got it. Thanks

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