The situation is the following we have not stable working Cisco RVS 4000 in a small network with no vlans assigned in it and only two serving subnets statically assigned so no DHCPs. Everything is powered by two separate connections from one ISP. the one is for the Cisco and its subnet and the second is routed by Mikrotik serving the other subnet. Everything is using one physical network with no VLANs. Is it possible the problem to be rooted in this share network and coexistance matter. With cheap router instead of this cisco everything is partially OK(connection dropping), but we use it because for the ACLs assigned for one of these subnets. Only one managed switch is used 3com Smartstack 3226, which is the main one with default config, after that no managed switches are used. Both routers are up to date with firmwares.

The mikrotik connection is working perfectly, the other subnet which is surved by This Cisco and also previously used Tp-link, etc. have problems with connection(dropping connection, ping, requests etc.) The ISP also uses Mikrotiks for their all city network. I don't know what is going on with this Cisco and the second subnet. No cable management problem, The config for the Cisco is OK nothing special static WAN IP and also static LAN IP some ACLs. ALL blocking services are off the problem still exists. Also IPS is off which caused Windows 7 connectivity problems.

closed as unclear what you're asking by Falcon Momot, jscott, Nathan C, Ward, Greg Askew Jul 15 '13 at 3:00

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    I think the problem is that the network is not stable. Not surprised. – gravyface Jul 14 '13 at 21:38
  • What is the symptom? – Falcon Momot Jul 14 '13 at 21:54

Without you providing more detail, it's difficult to say what the issue is with your second Internet connection that's handled by the Cisco.

I can tell you this:

Your setup is non-standard. Typically two Internet connections are managed by the same router in a load-balanced and/or failover configuration (and possibly using policy routing).

The LAN or "inside" network is typically the one and only subnet until there's:

a) a need to expand because the broadcast traffic is high;

b) too many hosts on the current network and the subnet is undersized;

c) reasons to isolate subnets from one another (DMZ, VoIP, wireless, wireless guests, etc.)

What I would suggest is to first rule out DNS. Nine times out of ten "Internet problems" are really a DNS problem. Either a bad forwarder configuration and/or a flaky ISP DNS (I typically use root hints or Google's public DNS: it's a tradeoff for latency, but I've seen too many small ISPs with poorly-managed, poorly-running DNS servers to trust them; data center DNS servers are generally better as are larger ISPs). Change your DNS forwarder to a public DNS server like Google's ( which is consistent and reliable and re-test.

After-hours and plug a laptop directly to the CPE router/modem/gateway the ISP provided you and set the static IP to the laptop and run some speed tests to see how the Internet connection behaves when you've ruled everything else out on your network.

If the Internet connection is working as expected consistently, next connect the Cisco back to it and run some tests from within the Cisco itself (ping, etc.).

If that checks out, then plug a laptop only into the Cisco along with the CPE router/modem/gateway and test the Internet again. This can help you address any potential NAT issues or misconfiguration.

If nothing is apparent or obvious, I would do a packet capture on the Cisco and on the laptop direct to the CPE router/modem/gateway, if that failed; you can Google how to do that or ask as another question on ServerFault, but you'll want to grab a copy of Wireshark for the laptop.

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