在Catalyst 9000交换机上配置并检验NAT
简介
本文档介绍如何在Catalyst 9000平台上配置和验证网络地址转换(NAT)。
先决条件
要求
Cisco 建议您了解以下主题：
- IP 编址
- 访问控制列表
背景信息
NAT最常见的情况是将私有IP网络空间转换为全球唯一的Internet可路由地址。
执行NAT的设备需要有一个内部网络上的接口（本地）和一个外部网络上的接口（全局）。
NAT设备负责检查源流量，以根据NAT规则配置确定是否需要转换。
如果需要转换，设备会将本地源IP地址转换为全局唯一的IP地址，并在其NAT转换表中跟踪此情况。
当数据包使用可路由地址返回时，设备会检查其NAT表，以查看是否有其他转换正在进行。
如果是，路由器会将内部全局地址转换回相应的内部本地地址并路由数据包。
使用的组件
通过Cisco IOS® XE 16.12.1 NAT现在可在Network Advantage许可证中找到。在所有早期版本中，DNA优势许可证中均提供此功能。
| Platform | 引入的NAT功能 |
| C9300 | 思科IOS® XE版本16.10.1 |
| C9400 | 思科IOS® XE版本17.1.1 |
| C9500 | 思科IOS® XE版本16.5.1a |
| C9600 | Cisco IOS® XE版本16.11.1 |
本文档基于采用Cisco IOS® XE版本16.12.4的Catalyst 9300平台
本文档中的信息都是基于特定实验室环境中的设备编写的。本文档中使用的所有设备最初均采用原始（默认）配置。如果您的网络处于活动状态，请确保您了解所有命令的潜在影响。
术语
| 静态 NAT | 允许本地地址到全局地址的一对一映射。 |
| 动态 NAT | 将本地地址映射到全局地址池。 |
| 过载NAT | 将本地地址映射到使用唯一L4端口的单个全局地址。 |
| 内部本地 | 分配给内部网络中主机的 IP 地址。 |
| 内部全局 | 这是内部主机显示给外部网络的IP地址。您可以将此地址视为内部本地地址转换到的地址。 |
| 外部本地 | 外部主机显现给内部网络的 IP 地址。 |
| 外部全局 | 分配给外部网络上主机的IP地址。在大多数情况下，外部本地地址和外部全局地址相同。 |
| FMAN-RP | 功能管理器RP。这是Cisco IOS® XE的控制平面，它将编程信息传递给FMAN-FP。 |
| FMAN-FP | 功能管理器FP。FMAN-FP接收来自FMAN-RP的信息并将其传递给FED。 |
| FED | 转发引擎驱动程序。FMAN-FP使用FED将来自控制平面的信息编程到统一接入数据平面(UADP)专用集成电路(ASIC)中。 |
网络图
配置
配置示例
将192.168.1.100（内部本地）转换为172.16.10.10（内部全局）的静态NAT配置：
NAT-Device#show run interface te1/0/1
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/1
no switchport
ip address 192.168.1.1 255.255.255.0
ip nat inside <-- NAT inside interface
end
NAT-Device#show run interface te1/0/2
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/2
no switchport
ip address 10.10.10.1 255.255.255.0
ip nat outside <-- NAT outside interface
end
ip nat inside source static 192.168.1.100 172.16.10.10 <-- static NAT rule
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.10.10:4 192.168.1.100:4 10.20.30.40:4 10.20.30.40:4 <-- active NAT translation
--- 172.16.10.10 192.168.1.100 --- --- <-- static NAT translation added as a result of the configuration
将192.168.1.0/24转换为172.16.10.1 ― 172.16.10.30的动态NAT配置：
NAT-Device#show run interface te1/0/1
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/1
no switchport
ip address 192.168.1.1 255.255.255.0
ip nat inside <-- NAT inside interface
end
NAT-Device#show run interface te1/0/2
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/2
no switchport
ip address 10.10.10.1 255.255.255.0
ip nat outside <-- NAT outside interface
end
!
ip nat pool TAC-POOL 172.16.10.1 172.16.10.30 netmask 255.255.255.224 <-- NAT pool configuration
ip nat inside source list hosts pool TAC-POOL <-- NAT rule configuration
!
ip access-list standard hosts <-- ACL to match hosts to be translated
10 permit 192.168.1.0 0.0.0.255
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.10.10:6 192.168.1.100:6 10.20.30.40:6 10.20.30.40:6
--- 172.16.10.10 192.168.1.100 --- ---
将192.168.1.0/24转换为10.10.10.1(ip nat outside interface)的动态NAT过载(PAT)配置：
NAT-Device#show run interface te1/0/1
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/1
no switchport
ip address 192.168.1.1 255.255.255.0
ip nat inside <-- NAT inside interface
end
NAT-Device#show run interface te1/0/2
Building configuration...
Current configuration : 109 bytes
!
interface TenGigabitEthernet1/0/2
no switchport
ip address 10.10.10.1 255.255.255.0
ip nat outside <-- NAT outside interface
end
!
ip nat inside source list hosts interface TenGigabitEthernet1/0/2 overload <-- NAT configuration to use PAT
!
ip access-list standard hosts <-- ACL to match hosts for translation
10 permit 192.168.1.0 0.0.0.255
注意，内部全局地址上的端口每次转换增加1：
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 10.10.10.1:1024 192.168.1.100:1 10.20.30.40:1 10.20.30.40:1024 <-- Notice layer 4 port increments
icmp 10.10.10.1:1025 192.168.1.100:2 10.20.30.40:2 10.20.30.40:1025 <-- Notice layer 4 port increments
icmp 10.10.10.1:1026 192.168.1.100:3 10.20.30.40:3 10.20.30.40:1026
icmp 10.10.10.1:1027 192.168.1.100:4 10.20.30.40:4 10.20.30.40:1027
icmp 10.10.10.1:1028 192.168.1.100:5 10.20.30.40:5 10.20.30.40:1028
icmp 10.10.10.1:1029 192.168.1.100:6 10.20.30.40:6 10.20.30.40:1029
icmp 10.10.10.1:1030 192.168.1.100:7 10.20.30.40:7 10.20.30.40:1030
icmp 10.10.10.1:1031 192.168.1.100:8 10.20.30.40:8 10.20.30.40:1031
10.10.10.1:1024 = inside global
192.168.1.100:1 = inside local
检验静态NAT
软件验证
如果没有转换的活动流，预计会看到一半的带静态NAT的转换。 当流变为活动状态时，将创建动态转换
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.10.10:10 192.168.1.100:10 10.20.30.40:10 10.20.30.40:10 <-- dynamic translation
--- 172.16.10.10 192.168.1.100 --- --- <-- static configuration from NAT rule configuration
使用show ip nat translations verbose命令，您可以确定创建流的时间和剩余转换时间。
NAT-Device#show ip nat translations verbose
Pro Inside global Inside local Outside local Outside global
icmp 172.16.10.10:10 192.168.1.100:10 10.20.30.40:10 10.20.30.40:10
create 00:00:13, use 00:00:13, left 00:00:46, <-- NAT timers
flags:
extended, use_count: 0, entry-id: 10, lc_entries: 0
--- 172.16.10.10 192.168.1.100 --- ---
create 00:09:47, use 00:00:13,
flags:
static, use_count: 1, entry-id: 9, lc_entries: 0
检查NAT统计信息。当流量与NAT规则匹配并创建时，NAT命中计数器将会增加。
当流量与规则匹配但无法创建转换时，NAT未命中计数器将会增加。
NAT-DEVICE#show ip nat statistics
Total active translations: 1 (1 static, 0 dynamic; 0 extended) <-- 1 static translation
Outside interfaces:
TenGigabitEthernet1/0/1 <-- NAT outside interface
Inside interfaces:
TenGigabitEthernet1/0/2 <-- NAT inside interface
Hits: 0 Misses: 0 <-- NAT hit and miss counters.
CEF Translated packets: 0, CEF Punted packets: 0
Expired translations: 0
Dynamic mappings:
-- Inside Source
[Id: 1] access-list hosts interface TenGigabitEthernet1/0/1 refcount 0
要进行转换，需要与NAT流的源和目标建立邻接关系。记下邻接ID。
NAT-Device#show ip route 10.20.30.40
Routing entry for 10.20.30.40/32
Known via "static", distance 1, metric 0
Routing Descriptor Blocks:
* 10.10.10.2
Route metric is 0, traffic share count is 1
NAT-Device#show platform software adjacency switch active f0
Adjacency id: 0x29(41) <-- adjacency ID
Interface: TenGigabitEthernet1/0/1, IF index: 52, Link Type: MCP_LINK_IP
Encap: 0:ca:e5:27:3f:e4:70:1f:53:0:b8:e4:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 192.168.1.100 <-- source adjacency
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 464, HW handle: (nil) (created)
Adjacency id: 0x24 (36) <-- adjacency ID
Interface: TenGigabitEthernet1/0/2, IF index: 53, Link Type: MCP_LINK_IP
Encap: 34:db:fd:ee:ce:e4:70:1f:53:0:b8:d6:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 10.10.10.2 <-- next hop to 10.20.30.40
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 452, HW handle: (nil) (created)
可以启用NAT调试，以验证交换机是否收到流量以及其是否创建了NAT流
NAT-Device#debug ip nat detailed
IP NAT detailed debugging is on
NAT-Device#
*Mar 8 23:48:25.672: NAT: Entry assigned id 11 <-- receive traffic and flow created
*Mar 8 23:48:25.672: NAT: i: icmp (192.168.1.100, 11) -> (10.20.30.40, 11) [55]
*Mar 8 23:48:25.672: NAT: s=192.168.1.100->172.16.10.10, d=10.20.30.40 [55]NAT: dyn flow info download suppressed for flow 11 <-- source is translated
*Mar 8 23:48:25.673: NAT: o: icmp (10.20.30.40, 11) -> (172.16.10.10, 11) [55]
*Mar 8 23:48:25.674: NAT: s=10.20.30.40, d=172.16.10.10->192.168.1.100 [55]NAT: dyn flow info download suppressed for flow 11 <-- return source is translated
*Mar 8 23:48:25.675: NAT: i: icmp (192.168.1.100, 11) -> (10.20.30.40, 11) [56]
<snip>
当流过期或被删除时，您会在调试中看到DELETE操作：
*Mar 31 17:58:31.344: FMANRP-NAT: Received flow data, action: DELETE <-- action is delete
*Mar 31 17:58:31.344: id 2, flags 0x1, domain 0
src_local_addr 192.168.1.100, src_global_addr 172.16.10.10, dst_local_addr 10.20.30.40,
dst_global_addr 10.20.30.40, src_local_port 31783, src_global_port 31783,
dst_local_port 23, dst_global_port 23,
proto 6, table_id 0 inside_mapping_id 0,
outside_mapping_id 0, inside_mapping_type 0,
outside_mapping_type 0
硬件验证
配置NAT规则后，设备在NAT区域5下的TCAM中对此规则进行编程。确认规则已在TCAM中编程。
输出以十六进制表示，因此需要转换到IP地址。
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 3
========================================================
Printing entries for region NAT_2 (371) type 6 asic 3
========================================================
Printing entries for region NAT_3 (372) type 6 asic 3
========================================================
Printing entries for region NAT_4 (373) type 6 asic 3
========================================================
Printing entries for region NAT_5 (374) type 6 asic 3 <-- NAT Region 5
========================================================
TAQ-2 Index-128 (A:1,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 3300f000:00000000:00000000:00000000:00000000:00000000:00000000:ffffffff
Key1 21009000:00000000:00000000:00000000:00000000:00000000:00000000:c0a80164 <-- inside local IP address 192.168.1.100 in hex (c0a80164)
AD 10087000:00000073
TAQ-2 Index-129 (A:1,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0300f000:00000000:00000000:00000000:00000000:00000000:ffffffff:00000000
Key1 02009000:00000000:00000000:00000000:00000000:00000000:ac100a0a:00000000 <-- inside global IP address 172.16.10.10 in hex (ac100a0a)
AD 10087000:00000073
最后，当数据流变为活动状态时，可以通过NAT区域1下的TCAM验证来确认硬件编程。
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 1 <-- NAT Region 1
========================================================
TAQ-2 Index-32 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:06005ac9:00000000:00000017:00000000:00000000:0a141e28:c0a80164
AD 10087000:000000b0
TAQ-2 Index-33 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:06000017:00000000:00005ac9:00000000:00000000:ac100a0a:0a141e28
AD 10087000:000000b1
Starting at Index-32 Key1 from right to left:
c0a80164 = 192.168.1.100 (Inside Local)
0a141e28 = 10.20.30.40 (Outside Global)
00000017 = 23 (TCP destination port)
06005ac9 = 06 for TCP and 5ac9 is 23241 which is source port from "show ip nat translations" of the inside host
Repeat the same for Index-33 which is the reverse translation:
0a141e28 = 10.20.30.40 (Outside Global)
ac100a0a = 172.16.10.10 (Inside Global)
00005ac9 = 23241 TCP Destination port
06000017 = 06 for TCP and 17 for TCP source port 23
检验动态NAT
软件验证
确认已配置要将内部IP地址转换到的地址池。
此配置允许将192.168.1.0/24网络转换为地址172.16.10.1到172.16.10.254
NAT-Device#show run | i ip nat
ip nat inside <-- ip nat inside on inside interface
ip nat outside <-- ip nat outside on outside interface
ip nat pool MYPOOL 172.16.10.1 172.16.10.254 netmask 255.255.255.0 <-- Pool of addresses to translate to
ip nat inside source list hosts pool MYPOOL <-- Enables hosts that match ACL "hosts" to be translated to MYPOOL addresses
NAT-Device#show ip access-list 10 <-- ACL to match hosts to be translated
Standard IP access list 10
10 permit 192.168.1.0, wildcard bits 0.0.0.255
NAT-Device#
请注意，使用动态NAT时，它不会创建任何仅包含配置的条目。需要在填充转换表之前创建活动流。
NAT-Device#show ip nat translations
<...empty...>
检查NAT统计信息。当流量与NAT规则匹配并创建时，NAT命中计数器将会增加。
当流量与规则匹配但无法创建转换时，NAT未命中计数器将会增加。
NAT-DEVICE#show ip nat statistics
Total active translations: 3794 (1 static, 3793 dynamic; 3793 extended) <-- dynamic translations
Outside interfaces:
TenGigabitEthernet1/0/1 <-- NAT outside interface
Inside interfaces:
TenGigabitEthernet1/0/2 <-- NAT inside interface
Hits: 3793 Misses: 0 <-- 3793 hits
CEF Translated packets: 0, CEF Punted packets: 0
Expired translations: 0
Dynamic mappings: <-- rule for dynamic mappings
-- Inside Source
[Id: 1] access-list hosts interface TenGigabitEthernet1/0/1 refcount 3793 <-- NAT rule displayed
确认存在与源和目标的邻接关系
NAT-Device#show platform software adjacency switch active f0
Number of adjacency objects: 4
Adjacency id: 0x24(36) <-- adjacency ID
Interface: TenGigabitEthernet1/0/2, IF index: 53, Link Type: MCP_LINK_IP
Encap: 34:db:fd:ee:ce:e4:70:1f:53:0:b8:d6:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 10.10.10.2 <-- adjacency to destination
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 449, HW handle: (nil) (created)
Adjacency id: 0x25 (37) <-- adjacency ID
Interface: TenGigabitEthernet1/0/1, IF index: 52, Link Type: MCP_LINK_IP
Encap: 0:ca:e5:27:3f:e4:70:1f:53:0:b8:e4:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 192.168.1.100 <-- source adjacency
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 451, HW handle: (nil) (created)
在确认邻接关系后，如果存在NAT问题，您可以开始进行独立于平台的NAT调试
NAT-Device#debug ip nat
IP NAT debugging is on
NAT-Device#debug ip nat detailed
IP NAT detailed debugging is on
NAT-Device#show logging
*May 13 01:00:41.136: NAT: Entry assigned id 6
*May 13 01:00:41.136: NAT: Entry assigned id 7
*May 13 01:00:41.136: NAT: i: tcp (192.168.1.100, 48308) -> (10.20.30.40, 23) [30067] <-- first packet ingress without NAT
*May 13 01:00:41.136: NAT: TCP Check for Limited ALG Support
*May 13 01:00:41.136: NAT: s=192.168.1.100->172.16.10.10, d=10.20.30.40 [30067]NAT: dyn flow info download suppressed for flow 7 <-- confirms source address translation
*May 13 01:00:41.136: NAT: attempting to setup alias for 172.16.10.10 (redundancy_name , idb NULL, flags 0x2), rg_id 0 tableid 0 use_tableid 0
*May 13 01:00:41.139: NAT: o: tcp (10.20.30.40, 23) -> (172.16.10.10, 48308) [40691] <-- return packet from destination to be translated
*May 13 01:00:41.139: NAT: TCP Check for Limited ALG Support
*May 13 01:00:41.139: NAT: s=10.20.30.40, d=172.16.10.10->192.168.1.100 [40691]NAT: dyn flow info download suppressed for flow 7 <-- return packet is translated
*May 13 01:00:41.140: NAT: i: tcp (192.168.1.100, 48308) -> (10.20.30.40, 23) [30068]
您还可以调试FMAN-RP NAT操作：
NAT-Device#debug platform software nat all
NAT platform all events debugging is on
Log Buffer (100000 bytes):
*May 13 01:04:16.098: FMANRP-NAT: Received flow data, action: ADD <-- first packet in flow so we ADD an entry
*May 13 01:04:16.098: id 9, flags 0x1, domain 0
src_local_addr 192.168.1.100, src_global_addr 172.16.10.10, dst_local_addr 10.20.30.40, <-- verify inside local/global and outside local/global
dst_global_addr 10.20.30.40, src_local_port 32529, src_global_port 32529,
dst_local_port 23, dst_global_port 23, <-- confirm ports, in this case they are for Telnet
proto 6, table_id 0 inside_mapping_id 1,
outside_mapping_id 0, inside_mapping_type 2,
outside_mapping_type 0
*May 13 01:04:16.098: FMANRP-NAT: Created TDL message for flow info:
ADD id 9
*May 13 01:04:16.098: FMANRP-NAT: Sent TDL message for flow data config:
ADD id 9
*May 13 01:04:16.098: FMANRP-NAT: Received flow data, action: MODIFY <-- subsequent packets are MODIFY
*May 13 01:04:16.098: id 9, flags 0x1, domain 0
src_local_addr 192.168.1.100, src_global_addr 172.16.10.10, dst_local_addr 10.20.30.40,
dst_global_addr 10.20.30.40, src_local_port 32529, src_global_port 32529,
dst_local_port 23, dst_global_port 23,
proto 6, table_id 0 inside_mapping_id 1,
outside_mapping_id 0, inside_mapping_type 2,
outside_mapping_type 0
*May 13 01:04:16.098: FMANRP-NAT: Created TDL message for flow info:
MODIFY id 9
*May 13 01:04:16.098: FMANRP-NAT: Sent TDL message for flow data config:
MODIFY id 9
如果由于任何原因（例如到期或手动删除）删除了规则，则会执行DELETE操作：
*May 13 01:05:20.276: FMANRP-NAT: Received flow data, action: DELETE <-- DELETE action
*May 13 01:05:20.276: id 9, flags 0x1, domain 0
src_local_addr 192.168.1.100, src_global_addr 172.16.10.10, dst_local_addr 10.20.30.40,
dst_global_addr 10.20.30.40, src_local_port 32529, src_global_port 32529,
dst_local_port 23, dst_global_port 23,
proto 6, table_id 0 inside_mapping_id 0,
outside_mapping_id 0, inside_mapping_type 0,
outside_mapping_type 0
硬件验证
检查是否在NAT区域5下的硬件中正确添加了匹配待转换流量的NAT规则：
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 1 <<<< empty due to no active flow
========================================================
Printing entries for region NAT_2 (371) type 6 asic 1
========================================================
Printing entries for region NAT_3 (372) type 6 asic 1
========================================================
Printing entries for region NAT_4 (373) type 6 asic 1
========================================================
Printing entries for region NAT_5 (374) type 6 asic 1
========================================================
TAQ-2 Index-128 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0300f000:00000000:00000000:00000000:00000000:00000000:fffffff8:00000000
Key1 02009000:00000000:00000000:00000000:00000000:00000000:ac100a00:00000000
AD 10087000:00000073
TAQ-2 Index-129 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 3300f000:00000000:00000000:00000000:00000000:00000000:00000000:ffffff00
Key1 21009000:00000000:00000000:00000000:00000000:00000000:00000000:c0a80100
AD 10087000:00000073
ffffff00 = 255.255.255.0 in hex
c0a80100 = 192.168.1.0 in hex which matches our network in the NAT ACL
最后，您需要确认在NAT TCAM区域1中正确编程了活动转换
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 172.16.10.10:54854 192.168.1.100:54854 10.20.30.40:23 10.20.30.40:23
--- 172.16.10.10 192.168.1.100 --- ---
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 1
========================================================
TAQ-2 Index-32 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:0600d646:00000000:00000017:00000000:00000000:0a141e28:c0a80164
AD 10087000:000000b0
TAQ-2 Index-33 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:06000017:00000000:0000d646:00000000:00000000:ac100a0a:0a141e28
AD 10087000:000000b1
Printing entries for region NAT_2 (371) type 6 asic 1
========================================================
Printing entries for region NAT_3 (372) type 6 asic 1
========================================================
Printing entries for region NAT_4 (373) type 6 asic 1
========================================================
Printing entries for region NAT_5 (374) type 6 asic 1
========================================================
Starting at Index-32 Key 1 from right to left:
c0a80164 - 192.168.1.100 (inside local)
0a141e28 - 10.20.30.40 (outside local/global)
00000017 - TCP port 23
0600d646 - 6 for TCP protocol and 54854 for TCP source port
Starting at Index-33 Key 1 from right to left
0a141e28 - 10.20.30.40 destination address
ac100a0a - 172.16.10.10 (inside global source IP address)
0000d646 - TCP source port
06000017 - TCP protocol 6 and 23 for the TCP destination port
检验动态NAT过载(PAT)
软件验证
用于检验PAT的日志进程与动态NAT相同。您只需确认端口转换是否正确，以及端口在硬件中编程是否正确。
PAT通过附加到NAT规则的“overload”关键字来实现。
NAT-Device#show run | i ip nat
ip nat inside <-- ip nat inside on NAT inside interface
ip nat outside <-- ip nat outside on NAT outside interface
ip nat pool MYPOOL 172.16.10.1 172.16.10.254 netmask 255.255.255.0 <-- Address pool to translate to
ip nat inside source list hosts pool MYPOOL overload <-- Links ACL hosts to address pool
确认存在与源和目标的邻接关系
NAT-Device#show ip route 10.20.30.40
Routing entry for 10.20.30.40/32
Known via "static", distance 1, metric 0
Routing Descriptor Blocks:
* 10.10.10.2
Route metric is 0, traffic share count is 1
NAT-Device#show platform software adjacency switch active f0
Number of adjacency objects: 4
Adjacency id: 0x24 (36) <-- adjacency ID
Interface: TenGigabitEthernet1/0/2, IF index: 53, Link Type: MCP_LINK_IP
Encap: 34:db:fd:ee:ce:e4:70:1f:53:0:b8:d6:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 10.10.10.2 <-- adjacency to destination
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 449, HW handle: (nil) (created)
Adjacency id: 0x25 (37) <-- adjacency ID
Interface: TenGigabitEthernet1/0/1, IF index: 52, Link Type: MCP_LINK_IP
Encap: 0:ca:e5:27:3f:e4:70:1f:53:0:b8:e4:8:0
Encap Length: 14, Encap Type: MCP_ET_ARPA, MTU: 1500
Flags: no-l3-inject
Incomplete behavior type: None
Fixup: unknown
Fixup_Flags_2: unknown
Nexthop addr: 192.168.1.100 <-- source adjacency
IP FRR MCP_ADJ_IPFRR_NONE 0
aom id: 451, HW handle: (nil) (created)
确认在流处于活动状态时转换已添加到转换表。请注意，使用PAT时，不会像使用动态NAT时那样创建半条目。
跟踪内部本地地址和内部全局地址上的端口号。
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 172.16.10.10:1024 192.168.1.100:52448 10.20.30.40:23 10.20.30.40:23
检查NAT统计信息。当流量与NAT规则匹配并创建时，NAT命中计数器将会增加。
当流量与规则匹配但无法创建转换时，NAT未命中计数器将会增加。
NAT-DEVICE#show ip nat statistics
Total active translations: 3794 (1 static, 3793 dynamic; 3793 extended) <-- dynamic translations
Outside interfaces:
TenGigabitEthernet1/0/1 <-- NAT outside interface
Inside interfaces:
TenGigabitEthernet1/0/2 <-- NAT inside interface
Hits: 3793 Misses: 0 <-- 3793 hits
CEF Translated packets: 0, CEF Punted packets: 0
Expired translations: 0
Dynamic mappings: <-- rule for dynamic mappings
-- Inside Source
[Id: 1] access-list hosts interface TenGigabitEthernet1/0/1 refcount 3793 <-- NAT rule displayed
独立于平台的NAT调试显示发生了端口转换：
NAT-Device#debug ip nat detailed
IP NAT detailed debugging is on
NAT-Device#debug ip nat
IP NAT debugging is on
NAT-device#show logging
Log Buffer (100000 bytes):
*May 18 23:52:20.296: NAT: address not stolen for 192.168.1.100, proto 6 port 52448
*May 18 23:52:20.296: NAT: Created portlist for proto tcp globaladdr 172.16.10.10
*May 18 23:52:20.296: NAT: Allocated Port for 192.168.1.100 -> 172.16.10.10: wanted 52448 got 1024<-- confirms PAT is used
*May 18 23:52:20.296: NAT: Entry assigned id 5
*May 18 23:52:20.296: NAT: i: tcp (192.168.1.100, 52448) -> (10.20.30.40, 23) [63338]
*May 18 23:52:20.296: NAT: TCP Check for Limited ALG Support
*May 18 23:52:20.296: NAT: TCP s=52448->1024, d=23 <-- confirms NAT overload with PAT
*May 18 23:52:20.296: NAT: s=192.168.1.100->172.16.10.10, d=10.20.30.40 [63338]NAT: dyn flow info download suppressed for flow 5 <-- shows inside translation
*May 18 23:52:20.297: NAT: attempting to setup alias for 172.16.10.10 (redundancy_name , idb NULL, flags 0x2), rg_id 0 tableid 0 use_tableid 0
*May 18 23:52:20.299: NAT: o: tcp (10.20.30.40, 23) -> (172.16.10.10, 1024) [55748]
*May 18 23:52:20.299: NAT: TCP Check for Limited ALG Support
*May 18 23:52:20.299: NAT: TCP s=23, d=1024->52448 <-- shows PAT on return traffic
*May 18 23:52:20.299: NAT: s=10.20.30.40, d=172.16.10.10->192.168.1.100 [55748]NAT: dyn flow info download suppressed for flow 5
NAT-Device#debug platform software nat all
NAT platform all events debugging is on
NAT-Device#
*May 18 23:52:20.301: FMANRP-NAT: Received flow data, action: ADD <-- first packet in flow ADD operation
*May 18 23:52:20.301: id 5, flags 0x5, domain 0
src_local_addr 192.168.1.100, src_global_addr 172.16.10.10, dst_local_addr 10.20.30.40, <-- source translation
dst_global_addr 10.20.30.40, src_local_port 52448, src_global_port 1024, <-- port translation
dst_local_port 23, dst_global_port 23,
proto 6, table_id 0 inside_mapping_id 1,
outside_mapping_id 0, inside_mapping_type 2,
outside_mapping_type 0
<snip>
硬件验证
在NAT区域5下的硬件中确认NAT规则已正确安装
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 1 <-- NAT_1 empty due to no active flow
========================================================
Printing entries for region NAT_2 (371) type 6 asic 1
========================================================
Printing entries for region NAT_3 (372) type 6 asic 1
========================================================
Printing entries for region NAT_4 (373) type 6 asic 1
========================================================
Printing entries for region NAT_5 (374) type 6 asic 1
========================================================
TAQ-2 Index-128 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0300f000:00000000:00000000:00000000:00000000:00000000:fffffffc:00000000
Key1 02009000:00000000:00000000:00000000:00000000:00000000:ac100a00:00000000
AD 10087000:00000073
TAQ-2 Index-129 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 3300f000:00000000:00000000:00000000:00000000:00000000:00000000:ffffff00
Key1 21009000:00000000:00000000:00000000:00000000:00000000:00000000:c0a80100
AD 10087000:00000073
ffffff00 = 255.255.255.0 in hex for our subnet mask in NAT ACL
c0a80100 = 192.168.1.0 in hex for our network address in NAT ACL
最后，当流处于活动状态时，可以检查NAT流是否已编程到NAT_Region 1下的硬件TCAM中
NAT-Device#show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 172.16.10.10:1024 192.168.1.100:20027 10.20.30.40:23 10.20.30.40:23
NAT-Device#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (370) type 6 asic 1 <-- NAT region 1
========================================================
TAQ-2 Index-32 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:06004e3b:00000000:00000017:00000000:00000000:0a141e28:c0a80164
AD 10087000:000000b0
TAQ-2 Index-33 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0000f000:ff00ffff:00000000:0000ffff:00000000:00000000:ffffffff:ffffffff
Key1 00009000:06000017:00000000:00000400:00000000:00000000:0a141e28:0a141e28
AD 10087000:000000b1
Starting at Index-32 Key1 from right to left:
c0a80164 - 192.168.1.100 (inside local source address)
0a141e28 - 10.20.30.40 (inside global address/outside local address)
00000017 - 23 (TCP destination port)
06004e3b - TCP source port 20027 (4e3b) and TCP protocol 6
Starting at Index-33 Key1 from right to left:
0a141e28 - 10.20.30.40 (outside global address/outside local address)
ac100a0a - 172.16.10.10 (inside global)
00000400 - TCP inside global source port 1024
06000017 - TCP protocol 6 and TCP source port 23
数据包级调试
数据流中第一个与硬件中的NAT规则匹配的数据包必须发送到设备CPU进行处理。要查看与传送路径相关的调试输出，可以将FED传送路径跟踪启用到调试级别，以确保数据包被传送。需要CPU资源的NAT流量进入中转流量CPU队列。
检查传输流量CPU队列是否看到数据包主动传送到该队列。
NAT-DEVICE#show platform software fed switch active punt cpuq clear <-- clear statistics
NAT-DEVICE#show platform software fed switch active punt cpuq 18 <-- transit traffic queue
Punt CPU Q Statistics
===========================================
CPU Q Id : 18
CPU Q Name : CPU_Q_TRANSIT_TRAFFIC
Packets received from ASIC : 0 <-- no punt traffic for NAT
Send to IOSd total attempts : 0
Send to IOSd failed count : 0
RX suspend count : 0
RX unsuspend count : 0
RX unsuspend send count : 0
RX unsuspend send failed count : 0
RX consumed count : 0
RX dropped count : 0
RX non-active dropped count : 0
RX conversion failure dropped : 0
RX INTACK count : 0
RX packets dq'd after intack : 0
Active RxQ event : 0
RX spurious interrupt : 0
RX phy_idb fetch failed: 0
RX table_id fetch failed: 0
RX invalid punt cause: 0
Replenish Stats for all rxq:
-------------------------------------------
Number of replenish : 0
Number of replenish suspend : 0
Number of replenish un-suspend : 0
-------------------------------------------
NAT-DEVICE#show platform software fed switch active punt cpuq 18 <-- after new translation
Punt CPU Q Statistics
===========================================
CPU Q Id : 18
CPU Q Name : CPU_Q_TRANSIT_TRAFFIC
Packets received from ASIC : 5 <-- confirms the UADP ASIC punts to CPU to create translation
Send to IOSd total attempts : 5
Send to IOSd failed count : 0
RX suspend count : 0
RX unsuspend count : 0
RX unsuspend send count : 0
RX unsuspend send failed count : 0
RX consumed count : 0
RX dropped count : 0
RX non-active dropped count : 0
RX conversion failure dropped : 0
RX INTACK count : 5
RX packets dq'd after intack : 0
Active RxQ event : 5
RX spurious interrupt : 0
RX phy_idb fetch failed: 0
RX table_id fetch failed: 0
RX invalid punt cause: 0
Replenish Stats for all rxq:
-------------------------------------------
Number of replenish : 18
Number of replenish suspend : 0
Number of replenish un-suspend : 0
-------------------------------------------
NAT扩展故障排除
当前硬件支持的最大NAT TCAM条目数，如下表所示：
| Platform | 最大TCAM条目数 |
| Catalyst 9300 | 5000 |
| Catalyst 9400 | 14000 |
| Catalyst 9500 | 14000 |
| Catalyst 9500高性能 | 15500 |
| Catalyst 9600 | 15500 |
如果您怀疑存在扩展问题，您可以确认要根据平台限制进行检查的TCP/UDP NAT转换总数。
NAT-Device#show ip nat translations | count tcp
Number of lines which match regexp = 621 <-- current number of TCP translations
NAT-Device#show ip nat translations | count udp
Number of lines which match regexp = 4894 <-- current number of UDP translations
如果您耗尽了NAT TCAM空间，则交换机硬件中的NAT模块无法处理这些转换。在此场景中，需要进行NAT转换的流量被传送至要处理的设备CPU。
这可能导致延迟，并且可以通过控制平面监察器队列中递增的丢弃确认，该队列负责NAT传送流量。NAT流量进入的CPU队列是“中转流量”。
NAT-Device#show platform hardware fed switch active qos queue stats internal cpu policer
CPU Queue Statistics
============================================================================================
(default) (set) Queue Queue
QId PlcIdx Queue Name Enabled Rate Rate Drop(Bytes) Drop(Frames)
--------------------------------------------------------------------------------------------
<snip>
14 13 Sw forwarding Yes 1000 1000 0 0
15 8 Topology Control Yes 13000 16000 0 0
16 12 Proto Snooping Yes 2000 2000 0 0
17 6 DHCP Snooping Yes 500 500 0 0
18 13 Transit Traffic Yes 1000 1000 34387271 399507 <-- drops for NAT traffic headed towards the CPU
19 10 RPF Failed Yes 250 250 0 0
20 15 MCAST END STATION Yes 2000 2000 0 0
<snip>
确认17.x代码中可用的NAT TCAM空间。此输出来自已激活NAT模板以最大化空间的9300。
NAT-DEVICE#show platform hardware fed switch active fwd-asic resource tcam utilization
Codes: EM - Exact_Match, I - Input, O - Output, IO - Input & Output, NA - Not Applicable
CAM Utilization for ASIC [0]
Table Subtype Dir Max Used %Used V4 V6 MPLS Other
------------------------------------------------------------------------------------------------------
Mac Address Table EM I 32768 22 0.07% 0 0 0 22
Mac Address Table TCAM I 1024 21 2.05% 0 0 0 21
L3 Multicast EM I 8192 0 0.00% 0 0 0 0
L3 Multicast TCAM I 512 9 1.76% 3 6 0 0
L2 Multicast EM I 8192 0 0.00% 0 0 0 0
L2 Multicast TCAM I 512 11 2.15% 3 8 0 0
IP Route Table EM I 24576 16 0.07% 15 0 1 0
IP Route Table TCAM I 8192 25 0.31% 12 10 2 1
QOS ACL TCAM IO 1024 85 8.30% 28 38 0 19
Security ACL TCAM IO 5120 148 2.89% 27 76 0 45
Netflow ACL TCAM I 256 6 2.34% 2 2 0 2
PBR ACL TCAM I 5120 24 0.47% 18 6 0 0 <-- NAT usage in PBR TCAM
Netflow ACL TCAM O 768 6 0.78% 2 2 0 2
Flow SPAN ACL TCAM IO 1024 13 1.27% 3 6 0 4
Control Plane TCAM I 512 281 54.88% 130 106 0 45
Tunnel Termination TCAM I 512 18 3.52% 8 10 0 0
Lisp Inst Mapping TCAM I 512 1 0.20% 0 0 0 1
Security Association TCAM I 256 4 1.56% 2 2 0 0
Security Association TCAM O 256 5 1.95% 0 0 0 5
CTS Cell Matrix/VPN
Label EM O 8192 0 0.00% 0 0 0 0
CTS Cell Matrix/VPN
Label TCAM O 512 1 0.20% 0 0 0 1
Client Table EM I 4096 0 0.00% 0 0 0 0
Client Table TCAM I 256 0 0.00% 0 0 0 0
Input Group LE TCAM I 1024 0 0.00% 0 0 0 0
Output Group LE TCAM O 1024 0 0.00% 0 0 0 0
Macsec SPD TCAM I 256 2 0.78% 0 0 0 2
确认16.x代码中可用的NAT TCAM空间。此输出来自带有SDM Access模板的9300，因此不会使NAT TCAM条目的可用空间最大化。
NAT-DEVICE#show platform hardware fed switch active fwd-asic resource tcam utilization
CAM Utilization for ASIC [0]
Table Max Values Used Values
--------------------------------------------------------------------------------
Unicast MAC addresses 32768/1024 20/21
L3 Multicast entries 8192/512 0/9
L2 Multicast entries 8192/512 0/11
Directly or indirectly connected routes 24576/8192 5/23
QoS Access Control Entries 5120 85
Security Access Control Entries 5120 145
Ingress Netflow ACEs 256 8
Policy Based Routing ACEs 1024 24 <-- NAT usage in PRB TCAM
Egress Netflow ACEs 768 8
Flow SPAN ACEs 1024 13
Control Plane Entries 512 255
Tunnels 512 17
Lisp Instance Mapping Entries 2048 3
Input Security Associations 256 4
SGT_DGT 8192/512 0/1
CLIENT_LE 4096/256 0/0
INPUT_GROUP_LE 1024 0
OUTPUT_GROUP_LE 1024 0
Macsec SPD 256 2
通过更改SDM模板以首选NAT，可以增加NAT TCAM的可用硬件空间。这将为TCAM条目的最大数量分配硬件支持。
NAT-Device#conf t
Enter configuration commands, one per line. End with CNTL/Z.
NAT-Device(config)#sdm prefer nat
如果将SDM在转换前后与NAT模板进行比较，则可确认可用TCAM空间已交换为QoS访问控制条目和基于策略的路由(PBR) ACE。
PBR TCAM是对NAT进行编程的位置。
NAT-Device#show sdm prefer
Showing SDM Template Info
This is the Access template.
Number of VLANs: 4094
Unicast MAC addresses: 32768
Overflow Unicast MAC addresses: 1024
L2 Multicast entries: 8192
Overflow L2 Multicast entries: 512
L3 Multicast entries: 8192
Overflow L3 Multicast entries: 512
Directly connected routes: 24576
Indirect routes: 8192
Security Access Control Entries: 5120
QoS Access Control Entries: 5120
Policy Based Routing ACEs: 1024 <-- NAT
<...snip...>
NAT-Device#show sdm prefer
Showing SDM Template Info
This is the NAT template.
Number of VLANs: 4094
Unicast MAC addresses: 32768
Overflow Unicast MAC addresses: 1024
L2 Multicast entries: 8192
Overflow L2 Multicast entries: 512
L3 Multicast entries: 8192
Overflow L3 Multicast entries: 512
Directly connected routes: 24576
Indirect routes: 8192
Security Access Control Entries: 5120
QoS Access Control Entries: 1024
Policy Based Routing ACEs: 5120 <-- NAT
<snip>
仅地址转换(AOT)
当NAT的要求是只转换IP地址字段而不是流的第4层端口时，可以使用AOT机制。如果这符合要求，则AOT可以大大增加硬件中要转换和转发的流的数量。
- 当大部分NAT流以单个或小型目标集为目的地时，AOT最有效。
- 默认情况下禁用AOT。启用后，需要清除当前的NAT转换。
这意味着仅允许AOT的NAT配置是：
#ip nat inside source static <source> <destination>
#ip nat inside source list <list> pool <pool name>
您可以使用以下命令启用AOT：
NAT-Device(config)#no ip nat create flow-entries
确认AOT NAT规则已正确编程。此输出来自静态NAT转换。
NAT-DEVICE#show running-config | include ip nat
ip nat outside
ip nat inside
no ip nat create flow-entries <-- AOT enabled
ip nat inside source static 10.10.10.100 172.16.10.10 <-- static NAT enabled
NAT-DEVICE#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (376) type 6 asic 1
========================================================
Printing entries for region NAT_2 (377) type 6 asic 1
========================================================
Printing entries for region NAT_3 (378) type 6 asic 1
========================================================
Printing entries for region NAT_4 (379) type 6 asic 1
========================================================
Printing entries for region NAT_5 (380) type 6 asic 1
========================================================
TAQ-1 Index-864 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 3300f000:00000000:00000000:00000000:00000000:00000000:00000000:ffffffff
Key1 21009000:00000000:00000000:00000000:00000000:00000000:00000000:0a0a0a64
AD 10087000:00000073
TAQ-1 Index-865 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0300f000:00000000:00000000:00000000:00000000:00000000:ffffffff:00000000
Key1 02009000:00000000:00000000:00000000:00000000:00000000:ac100a0a:00000000
AD 10087000:00000073
0a0a0a64 = 10.10.10.100 (inside local)
ac100a0a = 172.16.10.10 (inside global)
通过确认当流变为活动状态时仅对源和目标IP地址进行编程，验证TCAM中的AOT条目。
NAT-DEVICE#show platform hardware fed switch active fwd-asic resource tcam table pbr record 0 format 0 | begin NAT_1
Printing entries for region NAT_1 (376) type 6 asic 1
========================================================
Printing entries for region NAT_2 (377) type 6 asic 1
========================================================
TAQ-1 Index-224 (A:0,C:1) Valid StartF-1 StartA-1 SkipF-0 SkipA-0
Mask1 0000f000:00000000:00000000:00000000:00000000:00000000:ffffffff:ffffffff
Key1 00009000:00000000:00000000:00000000:00000000:00000000:c0a80164:0a0a0a64 <-- no L4 ports, only source and destination IP is programmed
AD 10087000:000000b2
TAQ-1 Index-225 (A:0,C:1) Valid StartF-0 StartA-0 SkipF-0 SkipA-0
Mask1 0000f000:00000000:00000000:00000000:00000000:00000000:ffffffff:00000000
Key1 00009000:00000000:00000000:00000000:00000000:00000000:ac100a0a:00000000
AD 10087000:000000b3
0a0a0a64 = 10.10.10.100 in hex (inside local IP address)
c0a80164 = 192.168.1.100 in hex (outside local/outside global)
ac100a0a = 172.16.10.10 (inside global)
相关信息
- Catalyst 9300 17.3.x NAT配置指南
- Catalyst 9400 17.3.x NAT配置指南
- Catalyst 9500 17.3.x NAT配置指南
- Catalyst 9600 17.3.x NAT配置指南
- 技术支持和文档 - Cisco Systems
修订历史记录
| 版本 | 发布日期 | 备注 |
|---|---|---|
5.0 |
10-May-2024 |
删除已显示的思科内部信息标题 |
4.0 |
11-May-2023 |
重新认证 |
3.0 |
08-Oct-2021 |
Version 1.1：
编辑空白距离，并将IP编址和访问控制列表从数字列表更改为项目符号列表。 |
2.0 |
29-Sep-2021 |
格式更改很小，没有新内容。 |
1.0 |
29-Sep-2021 |
初始版本 |
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