Slow LAN performance over 3G cellular connection
Posted on 2011-10-14
I have 18 remote sites connected to my datacenter over a MPLS network. I’m utilizing a wireless 3G cellular modem with Verizon (connected to my MPLS network) as a backup in the event I lose the T1.
The problem is when I fail-over, the internal network performance is terribly slow. However outbound to the internet is fine. If I download 3mb from the public internet it will take under a minute depending on the speed of the cellular site. The same file from a server on the inside takes over 2 -3 minutes. All 18 remote sites perform the same way. I do not have any problems when using the T1 circuits over the same hardware.
Remote site hardware
Cisco 2911 routers
HP procurve switch
Cisco 3845 router
Cisco 3845 stacked switches (3 vlans)
ASA5510 to the internet
BGP is used to update the MPLS network
When I connect the cellular failover it first will establishes a GRE tunnel with the datacenter. The datacenter is also the default route for everyone. The connections travels the same route out to the internet as it would to reach my internal server. Except when it hits my switch it’s separates per vlan. This is confirmed with a traceroute. Failover and connectivity is not a problem, just the performance is slow.
I don’t see why it would be slower internally when it takes the same path then out to the public internet, however the distance internally is shorter.
Any suggestion on where the bottle next would be?
Path with terrible performance
Server---Switch----router---- (GRE tunnel) ---router---switch (internal vlan) –server
Path with expected performance
Server---switch----router---- (GRE tunnel) ---router---switch (external vlan)--ASA---public internet
All help is greatly appreciated