Slow web browsing performance

Forum|Forum|13 years ago
March 6, 2013
3 replies
9136 views

Here' s how my scenario looks like: We had a Mikrotik RB1000 as our network edge with two Internet connections (one through an IPIP tunnel [2 Mbps] which was replaced by a GRE tunnel as IPIP tunnel cannot be set on Fortigate and it supports GRE, and the other through a dedicated fiber which is connected to Mikrotik from a line terminal [1.5 Mbps]). When I configured load balancing on Mikrotik, I experienced faulty web performance, after searching Mikrotik forums I figured out it was a fragmentation problem which was fixed by changing TCP syn packages' MSS (Max Segment Size) larger than 1360 to 1360 in forward chain. Now we have replaced our Mikrotik RB1000 with a Fortigate 311B configured load balancing on those two Internet connections on Fortigate; We' re experiencing the same faulty web browsing performance; What should I do? I know it is possible to set tcp-mss on Fortigate interfaces and I' ve done that but it didn' t solve my problem. Setting tcp-mss is different from setting MSS for only tcp syn packages, isn' t it?

rwpatterson

New Member

' Crappy' web browsing performance can be a result of several issues:

Check your WAN interface for duplex mismatch

diag hard dev nic <port>

Check for fragmentation (as you already stated). From Windows:

ping <internet host> -l <packet size> -f

Start at 1500 (the max) and decrease until you find the largest size that fits through the pipe.

Check your DNS server. I used this app: DNS Benchmark from GRC Research. You' ll be amazed at how much a slow DNS server can affect the browsing experience...

goftariAuthor

New Member

Thanks for your prompt and accurate reply Bob! As declared here, I did set tcp-mss to 1440 on the GRE tunnel; so is it necessary to also set MTU to a smaller value? as I mentioned there is a boolean MTU-override option available on the GRE tunnel. should I reduce the MTU size on the interface through which the tunnel is established and set this option to true?