This sample configuration describes how to configure Generic Routing Encapsulation (GRE) over IPSec between a Cisco VPN 5000 Concentrator and a Cisco IOS® router. The GRE-over-IPSec feature is introduced in the VPN 5000 Concentrator 6.0(19) software release.
The Routing Information Protocol (RIP) is used as the dynamic routing protocol in this sample to route traffic across the VPN tunnel.
There are no specific requirements for this document.
The information in this document is based on these software and hardware versions:
Cisco IOS Software Release 12.1(5)T7
VPN 5000 Concentrator Software Release 6.0(19)
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
For more information on document conventions, refer to Cisco Technical Tips Conventions.
In this section, you are presented with the information to configure the features described in this document.
Note: To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) .
This document uses the network setup shown in this diagram.
GRE over IPSec is configured between the Cisco IOS router (7140) and the Cisco VPN 5008 Concentrator. Behind these devices, multiple networks are advertised via RIP, which runs within the GRE tunnel between 7140 and VPN 5008.
Networks behind the Cisco 7140 are:
10.31.0.0/17
Networks behind the VPN 5008 are:
172.18.124.0.0/24
20.20.20.0/24
10.0.0.0/24
This document uses the configurations shown here.
Cisco IOS Router |
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Building configuration... Current configuration : 1607 bytes ! version 12.1 no service single-slot-reload-enable service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname 03-vpn-7140 ! boot system flash disk1:c7100-ik8s-mz.122-3 logging rate-limit console 10 except errors enable password <removed> ! ip subnet-zero ip cef ! ! no ip finger ! ! !--- Define phase 1 policy. crypto isakmp policy 10 authentication pre-share !--- Define the PreShared Key for the Remote peer !--- (5000 ) in this example. crypto isakmp key cisco123 address 10.32.1.161 ! !--- Define Phase 2 policy. !--- Make sure that Transport Mode is enabled. crypto ipsec transform-set www esp-des esp-sha-hmac mode transport ! !--- Define the crypto map that is later !--- applied on the outbound interface. crypto map temp 10 ipsec-isakmp set peer 10.32.1.161 set transform-set www match address 100 ! call rsvp-sync ! ! ! ! ! ! ! controller ISA 5/1 ! !--- Define the GRE tunnel on the router. !--- Tunnel source is the outbound interface !--- and tunnel destination is VPN 5000. interface Tunnel0 ip address 10.1.1.2 255.255.255.0 tunnel source FastEthernet0/0 tunnel destination 10.32.1.161 crypto map temp ! !--- Outbound Interface that is connected to the Internet. interface FastEthernet0/0 ip address 10.32.1.162 255.255.128.0 duplex auto speed auto crypto map temp ! ! !--- Inside interface. interface FastEthernet0/1 ip address 10.31.100.1 255.255.128.0 no keepalive duplex auto speed auto ! interface Serial1/0 no ip address shutdown framing c-bit cablelength 10 dsu bandwidth 44210 ! interface Serial1/1 no ip address shutdown framing c-bit cablelength 10 dsu bandwidth 44210 ! !--- Define RIP Routing Protocol on the router. !--- This example shows Version 2 for classless routing. router rip version 2 network 10.0.0.0 no auto-summary ! ip classless ip route 0.0.0.0 0.0.0.0 10.32.1.1 no ip http server ! !--- Encryption access-list that is used !--- to encrypt the GRE packets. access-list 100 permit gre host 10.32.1.162 host 10.32.1.161 ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 5 15 ! end |
VPN 5000 Concentrator |
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show configuration Edited Configuration not Present, using Running [ IP Ethernet 0:0 ] SubnetMask = 255.255.255.0 IPAddress = 1.1.1.1 [ IP Ethernet 1:0 ]Mode = Routed SubnetMask = 255.255.128.0 IPAddress = 10.32.1.161 [ General ] VPNGateway = 10.32.1.1 EnablePassword = <removed> Password = <removed> EthernetAddress = 00:00:a5:e9:c8:00 DeviceType = VPN 5002/8 Concentrator ConfiguredOn = Timeserver not configured ConfiguredFrom = Command Line, from Console [ IKE Policy ] Protection = SHA_DES_G1 [ IP Static ] 0.0.0.0 0.0.0.0 10.32.1.1 1 redist=none [ Context List ] flash://rip.cfg [ Logging ] Enabled = On Level = 7 Configuration size is 822 out of 65500 bytes. VPN5002_8_A5E9C800: Main# |
CVC |
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show configuration Edited Configuration not Present, using Running [ General ] Context = "rip" [ IP Ethernet 1:0.1 ] VLANID = 124 Encapsulation = dot1q Mode = Routed SubnetMask = 255.255.255.0 IPAddress = 172.18.124.219 [ IP Static ] [ Tunnel Partner VPN 1 ] InactivityTimeout = 120 Transform = esp(sha,des) KeyManage = ReliablePeer = "10.31.0.0/17" LocalAccess = "10.5.1.0/24" SharedKey = "cisco123" Mode = Main TunnelType = GREinIPSec BindTo = "Ethernet 1:0" Partner = 10.32.1.162 [ IP VPN 1 ] RIPIn = On RIPOut = On RIPVersion = V2 DirectedBroadcast = Off Numbered = On Mode = Routed SubnetMask = 255.255.255.0 IPAddress = 10.1.1.1 [ IP Ethernet 1:0.2 ] Mode = Routed SubnetMask = 255.255.255.0 IPAddress = 20.20.20.20 Configuration size is 1127 out of 65500 bytes. VPN5002_8_A5E9C800: rip# |
This section provides information you can use to confirm your configuration is working properly.
Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.
show ip route—Shows the current state of the routing table.
show crypto engine connection active—Shows the packet encryption/decryption counter per IPSec security association.
show crypto ipsec sa—Shows all current IPSec security associations.
show system log buffer —Shows basic syslog information.
vpn trace dump—Shows detailed information on VPN processes.
03-vpn-7140#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is 10.32.1.1 to network 0.0.0.0 20.0.0.0/24 is subnetted, 1 subnets R 20.20.20.0 [120/1] via 10.1.1.1, 00:00:10, Tunnel0 172.18.0.0/16 is variably subnetted, 2 subnets, 2 masks R 172.18.124.0/24 [120/1] via 10.1.1.1, 00:00:10, Tunnel0 10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks R 10.0.0.0/24 [120/2] via 10.1.1.1, 00:00:10, Tunnel0 C 10.1.1.0/24 is directly connected, Tunnel0 C 10.31.0.0/17 is directly connected, FastEthernet0/1 C 10.32.0.0/17 is directly connected, FastEthernet0/0 S* 0.0.0.0/0 [1/0] via 10.32.1.1 03-vpn-7140#
03-vpn-7140#show crypto enggine connection active ID Interface IP-Address State Algorithm Encrypt Decrypt 3 FastEthernet0/0 10.32.1.162 set HMAC_SHA+DES_56_CB 0 0 4 FastEthernet0/0 10.32.1.162 set HMAC_SHA+DES_56_CB 0 0 5 FastEthernet0/0 10.32.1.162 set HMAC_SHA+DES_56_CB 0 0 2098 FastEthernet0/0 10.32.1.162 set HMAC_SHA+DES_56_CB 0 1892 2099 FastEthernet0/0 10.32.1.162 set HMAC_SHA+DES_56_CB 11552 0
03-vpn-7140#show crypto ipsec sa interface: FastEthernet0/0 Crypto map tag: temp, local addr. 10.32.1.162 local ident (addr/mask/prot/port): (10.32.1.162/255.255.255.255/0/0) remote ident (addr/mask/prot/port): (10.32.1.161/255.255.255.255/0/0) current_peer: 10.32.1.161 PERMIT, flags={transport_parent,} #pkts encaps: 0, #pkts encrypt: 0, #pkts digest 0 #pkts decaps: 0, #pkts decrypt: 0, #pkts verify 0 #pkts compressed: 0, #pkts decompressed: 0 #pkts not compressed: 0, #pkts compr. failed: 0, #pkts decompress failed: 0 #send errors 0, #recv errors 0 local crypto endpt.: 10.32.1.162, remote crypto endpt.: 10.32.1.161 path mtu 1500, media mtu 1500 current outbound spi: 0 inbound esp sas: inbound ah sas: inbound pcp sas: outbound esp sas: outbound ah sas: outbound pcp sas: local ident (addr/mask/prot/port): (10.32.1.162/255.255.255.255/47/0) remote ident (addr/mask/prot/port): (10.32.1.161/255.255.255.255/47/0) current_peer: 10.32.1.161 PERMIT, flags={origin_is_acl,transport_parent,} #pkts encaps: 12912, #pkts encrypt: 12912, #pkts digest 12912 #pkts decaps: 2382, #pkts decrypt: 2382, #pkts verify 2382 #pkts compressed: 0, #pkts decompressed: 0 #pkts not compressed: 0, #pkts compr. failed: 0, #pkts decompress failed: 0 #send errors 0, #recv errors 0 local crypto endpt.: 10.32.1.162, remote crypto endpt.: 10.32.1.161 path mtu 1500, media mtu 1500 current outbound spi: 101 inbound esp sas: spi: 0x4624F3AD(1176826797) transform: esp-des esp-sha-hmac , in use settings ={Transport, } slot: 0, conn id: 2098, flow_id: 69, crypto map: temp sa timing: remaining key lifetime (k/sec): (1048130/3179) IV size: 8 bytes replay detection support: Y inbound ah sas: inbound pcp sas: outbound esp sas: spi: 0x101(257) transform: esp-des esp-sha-hmac , in use settings ={Transport, } slot: 0, conn id: 2099, flow_id: 70, crypto map: temp sa timing: remaining key lifetime (k/sec): (1046566/3179) IV size: 8 bytes replay detection support: Y outbound ah sas: outbound pcp sas: interface: Tunnel0 Crypto map tag: temp, local addr. 10.32.1.162 local ident (addr/mask/prot/port): (10.32.1.162/255.255.255.255/0/0) remote ident (addr/mask/prot/port): (10.32.1.161/255.255.255.255/0/0) current_peer: 10.32.1.161 PERMIT, flags={transport_parent,} #pkts encaps: 0, #pkts encrypt: 0, #pkts digest 0 #pkts decaps: 0, #pkts decrypt: 0, #pkts verify 0 #pkts compressed: 0, #pkts decompressed: 0 #pkts not compressed: 0, #pkts compr. failed: 0, #pkts decompress failed: 0 #send errors 0, #recv errors 0 local crypto endpt.: 10.32.1.162, remote crypto endpt.: 10.32.1.161 path mtu 1500, media mtu 1500 current outbound spi: 0 inbound esp sas: inbound ah sas: inbound pcp sas: outbound esp sas: outbound ah sas: outbound pcp sas: local ident (addr/mask/prot/port): (10.32.1.162/255.255.255.255/47/0) remote ident (addr/mask/prot/port): (10.32.1.161/255.255.255.255/47/0) current_peer: 10.32.1.161 PERMIT, flags={origin_is_acl,transport_parent,} #pkts encaps: 13017, #pkts encrypt: 13017, #pkts digest 13017 #pkts decaps: 2410, #pkts decrypt: 2410, #pkts verify 2410 #pkts compressed: 0, #pkts decompressed: 0 #pkts not compressed: 0, #pkts compr. failed: 0, #pkts decompress failed: 0 #send errors 0, #recv errors 0 local crypto endpt.: 10.32.1.162, remote crypto endpt.: 10.32.1.161 path mtu 1500, media mtu 1500 current outbound spi: 101 inbound esp sas: spi: 0x4624F3AD(1176826797) transform: esp-des esp-sha-hmac , in use settings ={Transport, } slot: 0, conn id: 2098, flow_id: 69, crypto map: temp sa timing: remaining key lifetime (k/sec): (1048124/3176) IV size: 8 bytes replay detection support: Y inbound ah sas: inbound pcp sas: outbound esp sas: spi: 0x101(257) transform: esp-des esp-sha-hmac , in use settings ={Transport, } slot: 0, conn id: 2099, flow_id: 70, crypto map: temp sa timing: remaining key lifetime (k/sec): (1046566/3176) IV size: 8 bytes replay detection support: Y outbound ah sas: outbound pcp sas:
This section provides information you can use to troubleshoot your configuration.
Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.
Note: Before issuing debug commands, please see Important Information on Debug Commands.
debug crypto isakmp (Cisco IOS Router)—Displays detailed information on Internet Key Exchange (IKE) phase I (Main Mode) negotiation.
debug crypto ipsec (Cisco IOS Router)—Displays detailed information on IKE phase II (Quick Mode) negotiation.
debug crypto engine (Cisco IOS Router)—Debugs the packet encryption/decryption and Diffie-Hellman (DH) process.
debug ip rip (Cisco IOS Router)—Debugs the RIP routing protocol.
Issue the show ip routing command from the VPN 5000 Concentrator.
VPN5002_8_A5E9C800: rip#show ip routing IP Routing Table for rip Directly Connected Routes: Destination Mask Ref Uses Type Interface 10.1.1.0 FFFFFF00 5 STIF VPN0:1 10.1.1.0 FFFFFFFF 0 STIF Local 10.1.1.1 @FFFFFFFF 5 LocalLocal 10.1.1.255 FFFFFFFF 0 STIF Local 20.20.20.0 FFFFFF00 1352 STIF Ether1:0.2 20.20.20.0 FFFFFFFF 0 STIF Local 20.20.20.20 @FFFFFFFF 14 LocalLocal 20.20.20.255 FFFFFFFF 1318 STIF Local 127.0.0.1 FFFFFFFF 0 STIF Local 172.18.124.0 FFFFFF00 13789 STIF Ether1:0.1 172.18.124.0 FFFFFFFF 0 STIF Local 172.18.124.219 @FFFFFFFF 6 LocalLocal 172.18.124.255 FFFFFFFF 13547 STIF Local 224.0.0.5 FFFFFFFF 0 STIF Local 224.0.0.6 FFFFFFFF 0 STIF Local 224.0.0.9 FFFFFFFF 15 STIF Local 255.255.255.255 @FFFFFFFF 221 LocalLocal Static Routes: Destination Mask Gateway Metric Ref Uses Type Interface 10.31.0.0 FFFF0000 Interface 1 0 Stat VPN0:1 10.32.1.162 @FFFFFFFF 10.32.1.161 2 0 *Stat VPN0:1 Dynamic Routes: Src/ Destination Mask Gateway Metric Ref Uses Type TTL Interface DEFAULT 10.1.1.2 1 293 RIP2 165 VPN0:1 10.0.0.0 FFFFFF00 172.18.124.216 1 0 RIP1 160 Ether1:0.1 10.31.0.0 FFFF8000 10.1.1.2 1 0 RIP2 165 VPN0:1 10.32.0.0 FFFF8000 10.1.1.2 1 0 RIP2 165 VPN0:1 Configured IP Routes: Destination Mask Gateway Metric IFnum Flags 10.31.0.0 FFFF0000 Interface 1 VPN 0:1 Redist = none Total Routes in use: 23 Mask -> @Host route Type -> Redist *rip #ospf
VPN5002_8_A5E9C800: rip#show vpn stat ver Current In High Running Script Script Script Active Negot Water Total Starts OK Error -------------------------------------------------------------- Users 0 0 0 0 0 0 0 Partners 1 0 1 1 1 0 0 Total 1 0 1 1 1 0 0 Stats VPN0:1 Wrapped 2697 Unwrapped 14439 BadEncap 0 BadAuth 0 BadEncrypt 0 rx IP 14439 rx IPX 0 rx Other 0 tx IP 2697 tx IPX 0 tx Other 0 IKE rekey 0 Input VPN pkts dropped due to no SA: 1 Input VPN pkts dropped due to no free queue entries: 0 IOP slot 1: Current In High Running Script Script Script Active Negot Water Total Starts OK Error -------------------------------------------------------------- Users 0 0 0 0 0 0 0 Partners 0 0 0 0 0 0 0 Total 0 0 0 0 0 0 0 Stats Wrapped Unwrapped BadEncap BadAuth BadEncrypt rx IP rx IPX rx Other tx IP tx IPX tx Other IKE rekey Input VPN pkts dropped due to no SA: 0 Input VPN pkts dropped due to no free queue entries: 0 IOP slot 2: Current In High Running Script Script Script Active Negot Water Total Starts OK Error -------------------------------------------------------------- Users 0 0 0 0 0 0 0 Partners 0 0 0 0 0 0 0 Total 0 0 0 0 0 0 0 Stats Wrapped Unwrapped BadEncap BadAuth BadEncrypt rx IP rx IPX rx Other tx IP tx IPX tx Other IKE rekey Input VPN pkts dropped due to no SA: 0 Input VPN pkts dropped due to no free queue entries: 0 IOP slot 3: Current In High Running Script Script Script Active Negot Water Total Starts OK Error -------------------------------------------------------------- Users 0 0 0 0 0 0 0 Partners 0 0 0 0 0 0 0 Total 0 0 0 0 0 0 0 Stats Wrapped Unwrapped BadEncap BadAuth BadEncrypt rx IP rx IPX rx Other tx IP tx IPX tx Other IKE rekey Input VPN pkts dropped due to no SA: 0 Input VPN pkts dropped due to no free queue entries: 0
Revision | Publish Date | Comments |
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1.0 |
09-Nov-2001 |
Initial Release |