Your company is extending their network by opening a new Remote Office in a different city. In the HeadQuarters, you run EIGRP between buildings and the design team has decided to add the Remote Office into the EIGRP domain and to maintain the same level of protection/privacy over the Internet.
To achieve this you must configure an IPsec tunnel and run EIGRP over it - you've chosen to use the old method of crypto maps with a GRE tunnel that allows you to run dynamic routing protocols over IPsec.
You perform the configuration below:
and you see that you have a successfull IPsec tunnel between HQ and Remote Office and the EIGRP peering is also UP:
HQ-Router#ping 172.16.255.2 Sending 5, 100-byte ICMP Echos to 172.16.255.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 52/76/100 ms HQ-Router# HQ-Router#sh crypto isakmp sa IPv4 Crypto ISAKMP SA dst src state conn-id slot status
126.96.36.199 188.8.131.52 QM_IDLE1001 0 ACTIVE HQ-Router# HQ-Router#sh crypto ipsec sa local ident (addr/mask/prot/port): (184.108.40.206/255.255.255.255/47/0) remote ident (addr/mask/prot/port): (220.127.116.11/255.255.255.255/47/0) ... #pkts encaps: 9, #pkts encrypt: 9, #pkts digest: 9 #pkts decaps: 8, #pkts decrypt: 8, #pkts verify: 8 ... HQ-Router# *Mar 1 01:35:27.435: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 172.16.255.2 (Tunnel1) is up: new adjacencyHQ-Router# HQ-Router#sh ip ei nei IP-EIGRP neighbors for process 100 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 3 172.16.255.2 Tu1 14 00:00:06 84 5000 0 292 172.16.3.2 Fa1/0 10 00:05:49 52 312 0 120 1 172.16.2.2 Fa0/1 13 00:05:51 53 318 0 119 0 172.16.1.2 Fa0/0 11 00:05:53 50 300 0 121 HQ-Router#
After a while, you are aproached by the NOC telling you that the new IPsec tunnel and the EIGRP neighborship keep flapping up and down, impacting the connectivity between HQ and the remote office.
What is the problem ?
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