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Network Administrator Guide

Troubleshooting Cisco IOS Customer Gateway Connectivity

When you troubleshoot the connectivity of a Cisco customer gateway you need to consider four things: IKE, IPsec, tunnel, and BGP. You can troubleshoot these areas any order, but we recommend that you start with IKE (at the bottom of the network stack) and move up.

IKE

Use the following command. The response shows a customer gateway with IKE configured correctly.

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router# show crypto isakmp sa
IPv4 Crypto ISAKMP SA
dst             src             state          conn-id slot status
192.168.37.160  72.21.209.193   QM_IDLE           2001    0 ACTIVE
192.168.37.160  72.21.209.225   QM_IDLE           2002    0 ACTIVE

You should see one or more lines containing a src of the Remote Gateway specified in the tunnels. The state should be QM_IDLE and status should be ACTIVE. The absence of an entry, or any entry in another indicate that IKE is not configured properly.

For further troubleshooting, run the following commands to enable log messages that provide diagnostic information.

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router# term mon router# debug crypto isakmp

To disable debugging, use the following command.

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router# no debug crypto isakmp

IPsec

Use the following command. The response shows a customer gateway with IPsec configured correctly.

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router# show crypto ipsec sa
interface: Tunnel1
    Crypto map tag: Tunnel1-head-0, local addr 192.168.37.160

    protected vrf: (none)
    local  ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0)
    remote ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0)
    current_peer 72.21.209.225 port 500
     PERMIT, flags={origin_is_acl,}
     #pkts encaps: 149, #pkts encrypt: 149, #pkts digest: 149
     #pkts decaps: 146, #pkts decrypt: 146, #pkts verify: 146
     #pkts compressed: 0, #pkts decompressed: 0
     #pkts not compressed: 0, #pkts compr. failed: 0
     #pkts not decompressed: 0, #pkts decompress failed: 0
     #send errors 0, #recv errors 0

     local crypto endpt.: 174.78.144.73, remote crypto endpt.: 72.21.209.225
     path mtu 1500, ip mtu 1500, ip mtu idb FastEthernet0
     current outbound spi: 0xB8357C22(3090512930)

     inbound esp sas:
      spi: 0x6ADB173(112046451)
       transform: esp-aes esp-sha-hmac ,
       in use settings ={Tunnel, }
       conn id: 1, flow_id: Motorola SEC 2.0:1, crypto map: Tunnel1-head-0
       sa timing: remaining key lifetime (k/sec): (4467148/3189)
       IV size: 16 bytes
       replay detection support: Y  replay window size: 128
       Status: ACTIVE

     inbound ah sas:

     inbound pcp sas:

     outbound esp sas:
      spi: 0xB8357C22(3090512930)
       transform: esp-aes esp-sha-hmac ,
       in use settings ={Tunnel, }
       conn id: 2, flow_id: Motorola SEC 2.0:2, crypto map: Tunnel1-head-0
       sa timing: remaining key lifetime (k/sec): (4467148/3189)
       IV size: 16 bytes
       replay detection support: Y  replay window size: 128
       Status: ACTIVE

     outbound ah sas:

     outbound pcp sas:

interface: Tunnel2
     Crypto map tag: Tunnel2-head-0, local addr 174.78.144.73

     protected vrf: (none)
     local  ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0)
     remote ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0)
     current_peer 72.21.209.193 port 500
      PERMIT, flags={origin_is_acl,}
     #pkts encaps: 26, #pkts encrypt: 26, #pkts digest: 26
     #pkts decaps: 24, #pkts decrypt: 24, #pkts verify: 24
     #pkts compressed: 0, #pkts decompressed: 0
     #pkts not compressed: 0, #pkts compr. failed: 0
     #pkts not decompressed: 0, #pkts decompress failed: 0
     #send errors 0, #recv errors 0

     local crypto endpt.: 174.78.144.73, remote crypto endpt.: 72.21.209.193
     path mtu 1500, ip mtu 1500, ip mtu idb FastEthernet0
     current outbound spi: 0xF59A3FF6(4120526838)

     inbound esp sas:
      spi: 0xB6720137(3060924727)
       transform: esp-aes esp-sha-hmac ,
       in use settings ={Tunnel, }
       conn id: 3, flow_id: Motorola SEC 2.0:3, crypto map: Tunnel2-head-0
       sa timing: remaining key lifetime (k/sec): (4387273/3492)
       IV size: 16 bytes
       replay detection support: Y  replay window size: 128
       Status: ACTIVE

     inbound ah sas:

     inbound pcp sas:

     outbound esp sas:
      spi: 0xF59A3FF6(4120526838)
       transform: esp-aes esp-sha-hmac ,
       in use settings ={Tunnel, }
       conn id: 4, flow_id: Motorola SEC 2.0:4, crypto map: Tunnel2-head-0
       sa timing: remaining key lifetime (k/sec): (4387273/3492)
       IV size: 16 bytes
       replay detection support: Y  replay window size: 128
       Status: ACTIVE

     outbound ah sas:

     outbound pcp sas:

For each tunnel interface, you should see both an inbound esp sas and outbound esp sas. Assuming an SA is listed ("spi: 0xF95D2F3C", for example) and the Status is ACTIVE, IPsec is configured correctly.

For further troubleshooting, use the following command to enable debugging.

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router# debug crypto ipsec

Use the following command to disable debugging.

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router# no debug crypto ipsec

Tunnel

First, check that you have the necessary firewall rules in place. For a list of the rules, see Configuring a Firewall Between the Internet and Your Customer Gateway.

If your firewall rules are set up correctly, then continue troubleshooting with the following command.

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router# show interfaces tun1
Tunnel1 is up, line protocol is up 
  Hardware is Tunnel
  Internet address is 169.254.255.2/30
  MTU 17867 bytes, BW 100 Kbit/sec, DLY 50000 usec, 
    reliability 255/255, txload 2/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 174.78.144.73, destination 72.21.209.225
  Tunnel protocol/transport IPSEC/IP
  Tunnel TTL 255
  Tunnel transport MTU 1427 bytes
  Tunnel transmit bandwidth 8000 (kbps)
  Tunnel receive bandwidth 8000 (kbps)
  Tunnel protection via IPSec (profile "ipsec-vpn-92df3bfb-0")
  Last input never, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 1 packets/sec
  5 minute output rate 1000 bits/sec, 1 packets/sec
    407 packets input, 30010 bytes, 0 no buffer
    Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

Ensure the line protocol is up. Check that the tunnel source IP address, source interface and destination respectively match the tunnel configuration for the customer gateway outside IP address, interface, and virtual private gateway outside IP address. Ensure that Tunnel protection via IPSec is present. Make sure to run the command on both tunnel interfaces. To resolve any problems here, review the configuration.

Also use the following command, replacing 169.254.255.1 with the inside IP address of your virtual private gateway.

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router# ping 169.254.255.1 df-bit size 1410
Type escape sequence to abort.
Sending 5, 1410-byte ICMP Echos to 169.254.255.1, timeout is 2 seconds:
Packet sent with the DF bit set
!!!!!

You should see 5 exclamation points.

For further troubleshooting, review the configuration.

BGP

Use the following command.

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router# show ip bgp summary
BGP router identifier 192.168.37.160, local AS number 65000
BGP table version is 8, main routing table version 8
2 network entries using 312 bytes of memory
2 path entries using 136 bytes of memory
3/1 BGP path/bestpath attribute entries using 444 bytes of memory
1 BGP AS-PATH entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
Bitfield cache entries: current 1 (at peak 2) using 32 bytes of memory
BGP using 948 total bytes of memory
BGP activity 4/1 prefixes, 4/1 paths, scan interval 15 secs

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
169.254.255.1   4  7224     363     323        8    0    0 00:54:21        1
169.254.255.5   4  7224     364     323        8    0    0 00:00:24        1

Here, both neighbors should be listed. For each, you should see a State/PfxRcd value of 1.

If the BGP peering is up, verify that your customer gateway router is advertising the default route (0.0.0.0/0) to the VPC.

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router# show bgp all neighbors 169.254.255.1 advertised-routes
For address family: IPv4 Unicast
BGP table version is 3, local router ID is 174.78.144.73
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
     r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Originating default network 0.0.0.0

Network             Next Hop            Metric   LocPrf Weight Path
*> 10.120.0.0/16    169.254.255.1          100        0   7224    i

Total number of prefixes 1

Additionally, ensure that you're receiving the prefix corresponding to your VPC from the virtual private gateway.

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router# show ip route bgp
	10.0.0.0/16 is subnetted, 1 subnets
B       10.255.0.0 [20/0] via 169.254.255.1, 00:00:20

For further troubleshooting, review the configuration.

Virtual Private Gateway Attachment

Make sure your virtual private gateway is attached to your VPC. Your integration team does this with the AWS Management Console.

If you have questions or need further assistance, please use the Amazon VPC forum.