I encounter a rare problem on ipsec tunnel .I configured 2 ipsec tunnel on 2 satellite network .center router is 2811 and branch routers are 878 with upgraded ios . every thing were good up to 3months . suddenly both ipsec tunnels disconnected but ip connection haven't any problem and I could ping all routers. First I thought provider may installed firewall but he didn't. I debug ipsec traffic and found that connection were established and disconnect immediately . I asked satellite provider about any change in network and found that delay(RTT) is increased to 650 ms. now will appreciate help me .