I posted an issue I was having here a while ago. The router internal interface would go down intermittently. From the switch I could see all internal interfaces were up and I machines within the LAN could communicate; however they could not access the Internet. From the router I could ping the Internet and not the Internal LAN. I didn't get responses on this so I asked someone from another company to take a look. He suggested I take out all the managed switches in the LAN and replace them with unmanaged ones. I did this and the network has been stable since. He says that he's had this problem before on a network that was connecting to the Internet using a cisco router where the ISP is also using a cisco router. He says it has something to do with having similar vlans both at the ISP and on my LAN. Has anyone experienced this and if so, is this a bug in the cisco devices? As far as I know, cisco routers aren't supposed to forward intervlan traffic from the Internet.
Parvesh I cannot ping the router internal interface from a host in the LAN and therefore cannot access the Internet via that host. From a router console I get a response from t ping to a host on the Internet e.g. 8.8.8.8 but not one from a host inside the LAN. The switch(mananged) has minimal configurations, actually it only has the default configs i.e. only vlan 1, stp enabled etc.
