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# 排除与 Cisco IOS 客户网关设备的 AWS Site-to-Site VPN 连接故障
对 Cisco 客户网关设备的连接进行故障排除时，请考虑四件事：IKE IPsec、隧道和 BGP。您可以按任何次序对这些方面进行故障排除，不过建议您从 IKE 开始（位于网络堆栈的底部）并依次向上排除。
## IKE
使用以下命令。响应显示带正确配置的 IKE 的客户网关设备。
```
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
```
您应该可以看到包含隧道中所指定远程网关的 `src` 值的一行或多行。`state` 应为 `QM_IDLE`，`status` 应为 `ACTIVE`。任何项的缺乏或任何项处于其他状态均表示 IKE 未正确配置。
如需进一步排除故障，请运行下面的命令以启用可提供诊断信息的日志消息。
```
router# term mon
router# debug crypto isakmp
```
要禁用调试，请使用下面的命令。
```
router# no debug crypto isakmp
```
## IPsec
使用以下命令。响应显示 IPsec配置正确的客户网关设备。
```
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:
```
对于每个隧道接口，您应该可以看到 `inbound esp sas` 和 `outbound esp sas`。假设 SA 已列出（`spi: 0xF95D2F3C`例如）`ACTIVE`，`Status`并且配置 IPsec 正确。
如需进一步排除故障，请使用下面的命令启用调试。
```
router# debug crypto ipsec
```
使用下面的命令禁用调试。
```
router# no debug crypto ipsec
```
## 隧道
首先，检查必要的防火墙规则是否已布置到位。有关更多信息，请参阅 [AWS Site-to-Site VPN 客户网关设备的防火墙规则](FirewallRules.md)。
如果您的防火墙规则设置正确，则请使用下面的命令继续排除故障。
```
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
```
确保 `line protocol` 已运行。检查隧道源 IP 地址、源接口和目的地分别匹配客户网关设备外部 IP 地址、接口和虚拟私有网关外部 IP 地址的隧道配置。确保 `Tunnel protection via IPSec` 已存在。在两个隧道接口上运行命令。要解决任何问题，请查看配置并检查与客户网关设备的物理连接。
另外请使用下面的命令，将 `169.254.255.1` 替换为您的虚拟专用网关的内部 IP 地址。
```
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
!!!!!
```
您应该可以看到五个感叹号。
如需进一步排查问题，请核查配置。
## BGP
使用以下命令。
```
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
```
两个邻系统均已列出。对于每个系统，您应看到 `State/PfxRcd` 值为 `1`。
如果 BGP 对等体已运行，请验证您的客户网关设备正在向 VPC 通告默认路由 (0.0.0.0/0)。
```
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
```
另外，请确保您正在从虚拟专用网关接收对应于您的 VPC 的前缀。
```
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
```
如需进一步排查问题，请核查配置。