本產品的文件集力求使用無偏見用語。針對本文件集的目的,無偏見係定義為未根據年齡、身心障礙、性別、種族身分、民族身分、性別傾向、社會經濟地位及交織性表示歧視的用語。由於本產品軟體使用者介面中硬式編碼的語言、根據 RFP 文件使用的語言,或引用第三方產品的語言,因此本文件中可能會出現例外狀況。深入瞭解思科如何使用包容性用語。
思科已使用電腦和人工技術翻譯本文件,讓全世界的使用者能夠以自己的語言理解支援內容。請注意,即使是最佳機器翻譯,也不如專業譯者翻譯的內容準確。Cisco Systems, Inc. 對這些翻譯的準確度概不負責,並建議一律查看原始英文文件(提供連結)。
本文檔介紹在SD-WAN重疊中的多個VPN中地址空間重疊的場景。它描述了示例網路、正常/故障切換情況下的流量行為、配置和驗證。
Cisco建議您應具備SD-WAN的相關知識。
本文中的資訊係根據以下軟體和硬體版本:
Cisco IOS® XE(在控制器模式下運行) 17.6.3a
本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除(預設)的組態來啟動。如果您的網路運作中,請確保您瞭解任何指令可能造成的影響。
您可以在此處找到本文中使用的縮寫詞清單。
有關服務端NAT:服務端NAT的詳細資訊,請參閱Cisco文檔
注意:在此拓撲中,每個分支路由器的服務VPN 10中託管的裝置都配置了重疊的IP 192.168.10.0/24。
在此特定拓撲中,有1個DC(DC只有MPLS傳輸,但在實際場景中可能有多個傳輸)和2個分支機構位置透過MPLS和Internet傳輸連線到SD-WAN覆蓋。所有位置都配置了服務VPN 10。分支已將SIG隧道(主隧道和備用隧道)配置為Zscaler。DIA針對特定目標IP進行配置,以繞過Zscaler。如果分支機構的Internet鏈路發生故障,則所有流量必須透過MPLS傳輸傳送到DC。
eBGP在服務VPN 10上配置,DC端使用Zscaler路由器。DC路由器接收來自Zscaler路由器的預設路由,並將其重分配到OMP中。
注意:本實驗場景中提到的公用IP地址取自文檔RFC5737。
為實現這一要求,使用了SD-WAN功能服務端NAT和帶資料策略的DIA。
注意:要描述從VPN 10到SIG隧道的正常資料流,使用公共IP 192.0.2.100;對於特定目標,使用DIA 192.0.2.1。相應的配置顯示在配置部分中。
Branch-1路由器的配置如下。
vrf definition 10
rd 1:10
!
address-family ipv4
route-target export 1:10
route-target import 1:10
exit-address-family
!
interface GigabitEthernet2
description "Internet TLOC"
ip address 198.51.100.1 255.255.255.0
ip nat outside
!
interface GigabitEthernet3
description "MPLS TLOC"
ip address 172.20.1.10 255.255.255.0
!
interface GigabitEthernet4
description "Service Side VPN 10"
vrf forwarding 10
ip address 192.168.10.1 255.255.255.0
!
interface Tunnel2
ip unnumbered GigabitEthernet2
tunnel source GigabitEthernet2
tunnel mode sdwan
!
interface Tunnel3
ip unnumbered GigabitEthernet3
tunnel source GigabitEthernet3
tunnel mode sdwan
!
interface Tunnel100512
ip address 10.10.1.1 255.255.255.252
tunnel source GigabitEthernet2
tunnel destination 203.0.113.1
tunnel vrf multiplexing
!
interface Tunnel100513
ip address 10.10.1.5 255.255.255.252
tunnel source GigabitEthernet2
tunnel destination 203.0.113.2
tunnel vrf multiplexing
!
ip sdwan route vrf 10 0.0.0.0/0 tunnel active Tunnel100512 backup Tunnel100513
ip nat pool natpool1 172.16.2.1 172.16.2.2 prefix-length 30
ip nat inside source list nat-dia-vpn-hop-access-list interface GigabitEthernet2 overload
ip nat inside source list global-list pool natpool1 vrf 10 match-in-vrf overload
ip nat route vrf 10 192.0.2.1 255.255.255.255 global
!
ip route 0.0.0.0 0.0.0.0 198.51.100.100
ip route 0.0.0.0 0.0.0.0 172.20.1.100
!
Branch-2路由器的配置如下。
vrf definition 10
rd 1:10
!
address-family ipv4
route-target export 1:10
route-target import 1:10
exit-address-family
!
address-family ipv6
exit-address-family
!
interface GigabitEthernet2
description "Internet TLOC"
ip address 198.51.100.2 255.255.255.0
ip nat outside
!
!
interface GigabitEthernet3
description "MPLS TLOC"
ip address 172.20.1.20 255.255.255.0
!
interface GigabitEthernet4
description "Service Side VPN 10"
vrf forwarding 10
ip address 192.168.10.1 255.255.255.0
!
interface Tunnel2
ip unnumbered GigabitEthernet2
tunnel source GigabitEthernet2
tunnel mode sdwan
!
interface Tunnel3
ip unnumbered GigabitEthernet3
tunnel source GigabitEthernet3
tunnel mode sdwan
!
interface Tunnel100512
ip address 10.10.2.1 255.255.255.252
tunnel source GigabitEthernet2
tunnel destination 203.0.113.1
tunnel vrf multiplexing
!
interface Tunnel100513
ip address 10.10.2.5 255.255.255.252
tunnel source GigabitEthernet2
tunnel destination 203.0.113.2
tunnel vrf multiplexing
!
!
ip sdwan route vrf 10 0.0.0.0/0 tunnel active Tunnel100512 backup Tunnel100513
ip nat route vrf 10 192.0.2.1 255.255.255.255 global
ip nat pool natpool1 172.16.2.9 172.16.2.10 prefix-length 30
ip nat inside source list nat-dia-vpn-hop-access-list interface GigabitEthernet2 overload
ip nat inside source list global-list pool natpool1 vrf 10 match-in-vrf overload
!
ip route 0.0.0.0 0.0.0.0 198.51.100.100
ip route 0.0.0.0 0.0.0.0 172.20.1.100
!
DC路由器配置如下。
vrf definition 10
rd 1:10
!
address-family ipv4
route-target export 10:10
route-target import 10:10
exit-address-family
!
interface Tunnel2
ip unnumbered GigabitEthernet2
tunnel source GigabitEthernet2
tunnel mode sdwan
!
interface GigabitEthernet2
ip address 172.20.1.30 255.255.255.0
description "MPLS TLOC"
!
interface GigabitEthernet4
description "Service Side VPN 10"
vrf forwarding 10
ip address 172.31.19.19 255.255.255.252
!
router bgp 10
bgp log-neighbor-changes
distance bgp 20 200 20
!
address-family ipv4 vrf 10
redistribute omp
neighbor 172.31.19.20 remote-as 100
neighbor 172.31.19.20 activate
neighbor 172.31.19.20 send-community both
exit-address-family
!
!
ip route 0.0.0.0 0.0.0.0 172.20.1.100
!
vSmart策略配置如下。
注意:請注意,兩個分支的策略中均 nat pool 1 被呼叫,但每個分支都配置了兩個不同的IP池(Branch-1為172.16.2.0/30,Branch-2為172.16.2.8/30)。
data-policy _VPN10-VPN20_1-Branch-A-B-Central-NAT-DIA
vpn-list VPN10
sequence 1
match
source-ip 192.168.10.0/24
!
action accept
nat pool 1
!
default-action accept
!
site-list BranchA-B
site-id 11
site-id 22
!
site-list DC
site-id 33
!
vpn-list VPN10
vpn 10
!
prefix-list _AnyIpv4PrefixList
ip-prefix 0.0.0.0/0 le 32
!
apply-policy
site-list BranchA-B
data-policy _VPN10_1-Branch-A-B-Central-NAT-DIA from-service
!
容錯移轉案例
Branch-1流量正常場景
當兩個傳輸都如輸出所示運行時,預設情況下流量透過主SIG隧道
Tunnel100512退出。 當主隧道關閉時,流量會切換到備用隧道
Tunnel100513。
Branch-1#show ip route vrf 10
Routing Table: 10
<SNIP>
Gateway of last resort is 0.0.0.0 to network 0.0.0.0
S* 0.0.0.0/0 [2/0], Tunnel100512
192.0.2.0/32 is subnetted, 1 subnets
n Nd 192.0.2.1 [6/0], 3d02h, Null0
n Ni 172.16.2.0 [7/0], 3d04h, Null0
m 172.16.2.8 [251/0] via 172.31.31.2, 3d01h, Sdwan-system-intf
Branch-1#
Traceroute顯示流量透過SIG隧道。
Host-BR-1#ping 192.0.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/49/101 ms
Host-BR-1#
Host-BR-1#traceroute 192.0.2.100 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.100
VRF info: (vrf in name/id, vrf out name/id)
1 192.168.10.1 38 msec 7 msec 4 msec
2 203.0.113.1 79 msec * 62 msec
Host-BR-1#
發往特定目的地的流量
192.0.2.1 透過DIA(NAT連線到WAN IP地址)退出。
Host-BR-1#ping 192.0.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/49/101 ms
Host-BR-1#
Branch-1#sh ip nat translation
Pro Inside global Inside local Outside local Outside global
icmp 198.51.100.1:1 192.168.10.10:1 192.0.2.1:1 192.0.2.1:1
Total number of translations: 1
Branch-1#
Branch-2流量正常場景
在Branch-2路由器上也觀察到類似行為。
Branch-2#show ip route vrf 10
Routing Table: 10
<SNIP>
Gateway of last resort is 0.0.0.0 to network 0.0.0.0
S* 0.0.0.0/0 [2/0], Tunnel100512
192.0.2.0/32 is subnetted, 1 subnets
n Nd 192.0.2.1 [6/0], 00:00:08, Null0
m 172.16.2.0 [251/0] via 172.31.31.1, 3d01h, Sdwan-system-intf
n Ni 172.16.2.8 [7/0], 3d04h, Null0
Branch-2#
Host-BR-2#ping 192.0.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/49/101 ms
Host-BR-2#
Host-BR-2#traceroute 192.0.2.100 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.100
VRF info: (vrf in name/id, vrf out name/id)
1 192.168.10.1 38 msec 7 msec 4 msec
2 203.0.113.1 79 msec * 62 msec
Host-BR-2#
Host-BR-2#ping 192.0.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/49/101 ms
Host-BR-2#
Branch-2#show ip nat translation
Pro Inside global Inside local Outside local Outside global
icmp 198.51.100.2:1 192.168.10.10:1 192.0.2.1:1 192.0.2.1:1
Total number of translations: 1
Branch-2#
失敗案例
Branch-1故障場景
本節說明網際網路失敗期間的行為。
Internet鏈路被管理性關閉以模擬Internet故障鏈路。
Branch-1#show sdwan control local-properties
<SNIP>
PUBLIC PUBLIC PRIVATE PRIVATE PRIVATE MAX
INTERFACE IPv4 PORT IPv4 IPv6 PORT VS/VM COLOR STATE CNTRL
---------------------------------------------------------------------------------------------------------------------
GigabitEthernet2 198.51.100.1 12346 198.51.100.1 :: 12346 1/0 biz-internet down
GigabitEthernet3 172.20.1.10 12346 172.20.1.10 :: 12346 1/1 mpls up
Branch-1#
輸出顯示,在Internet鏈路故障情況下,Branch 1路由器透過OMP從DC路由器接收預設路由。172.31.31.3是DC路由器的系統IP。
Branch-1#show ip route vrf 10
<SNIP>
Gateway of last resort is 172.31.31.3 to network 0.0.0.0
m* 0.0.0.0/0 [251/0] via 172.31.31.3, 00:01:17, Sdwan-system-intf
<SNIP>
發往
192.0.2.100的流量被NAT轉換成服務端NAT池,然後透過DC退出。
Host-BR-1#ping 192.0.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/37/103 ms
Host-BR-1#
Branch-1#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.2.1:3 192.168.10.1:3 192.0.2.100:3 192.0.2.100:3
Total number of translations: 1
Branch-1#
Traceroute結果顯示,流量採用DC路徑。172.20.1.30是DC路由器的MPLS傳輸WAN IP。
Host-BR-1#traceroute 192.0.2.100 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.100
1 192.168.10.1 26 msec 5 msec 3 msec
2 172.20.1.30 10 msec 5 msec 27 msec
<SNIP>
Branch-1#show sdwan bfd sessions
SOURCE TLOC REMOTE TLOC DST PUBLIC DST PUBLIC DETECT TX
SYSTEM IP SITE ID STATE COLOR COLOR SOURCE IP IP PORT ENCAP MULTIPLIER INTERVAL(msec) UPTIME TRANSITIONS
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
172.31.31.2 22 up mpls mpls 172.20.1.10 172.20.1.20 12406 ipsec 7 1000 0:14:56:54 0
172.31.31.3 33 up mpls mpls 172.20.1.10 172.20.1.30 12406 ipsec 7 1000 0:14:56:57 0
Branch-1#
發往特定IP 192.0.2.1的流量也被NAT連線到服務端NAT池並透過DC退出。
Host-BR-1#ping 192.0.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/37/103 ms
Host-BR-1#
Branch-1#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.2.1:4 192.168.10.10:4 192.0.2.1:4 192.0.2.1:4
Total number of translations: 1
Branch-1#
Host-BR-1#traceroute 192.0.2.1 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.1
1 192.168.10.1 26 msec 5 msec 3 msec
2 172.20.1.30 10 msec 5 msec 27 msec
<SNIP>
從vSmart推送的資料策略配置:
Branch-1#show sdwan policy from-vsmart
from-vsmart data-policy _VPN10-VPN20_1-Branch-A-B-Central-NAT-DIA
direction from-service
vpn-list VPN10
sequence 1
match
source-ip 192.168.10.0/24
action accept
count NAT_VRF10_BRANCH_A_B_-968382210
nat pool 1
!
from-vsmart lists vpn-list VPN10
vpn 10
!
Branch-1#
Branch-1#show run | sec "natpool1"
<SNIP>
ip nat pool natpool1 172.16.2.1 172.16.2.2 prefix-length 30
Branch-2故障場景
在發生Internet故障切換時,Branch-2路由器中也會出現類似行為。
Branch-2#show sdwan control local-properties
<SNIP>
PUBLIC PUBLIC PRIVATE PRIVATE PRIVATE MAX
INTERFACE IPv4 PORT IPv4 IPv6 PORT VS/VM COLOR STATE CNTRL
---------------------------------------------------------------------------------------------------------------------
GigabitEthernet2 198.51.100.2 12346 198.51.100.2 :: 12346 1/0 biz-internet down
GigabitEthernet3 172.20.1.20 12346 172.20.1.20 :: 12346 1/1 mpls up
Branch-2#
Branch-2#show ip route vrf 10
<SNIP>
Gateway of last resort is 172.31.31.3 to network 0.0.0.0
m* 0.0.0.0/0 [251/0] via 172.31.31.3, 00:10:17, Sdwan-system-intf
<SNIP>
Host-BR-2#ping 192.0.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/37/103 ms
Host-BR-2#
Branch-2#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.2.9:3 192.168.10.1:3 192.0.2.100:3 192.0.2.100:3
Total number of translations: 1
Branch-2#
Host-BR-2#traceroute 192.0.2.100 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.100
1 192.168.10.1 26 msec 5 msec 3 msec
2 172.20.1.30 10 msec 5 msec 27 msec
<SNIP>
Host-BR-2#ping 192.0.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/37/103 ms
Host-BR-2#
Branch-2#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.2.9:4 192.168.10.10:4 192.0.2.1:4 192.0.2.1:4
Total number of translations: 1
Branch-2#
Host-BR-2#traceroute 192.0.2.1 numeric
Type escape sequence to abort.
Tracing the route to 192.0.2.1
1 192.168.10.1 26 msec 5 msec 3 msec
2 172.20.1.30 10 msec 5 msec 27 msec
<SNIP>
Branch-2#show sdwan policy from-vsmart
from-vsmart data-policy _VPN10-VPN20_1-Branch-A-B-Central-NAT-DIA
direction from-service
vpn-list VPN10
sequence 1
match
source-ip 192.168.10.0/24
action accept
count NAT_VRF10_BRANCH_A_B_-968382210
nat pool 1
!
from-vsmart lists vpn-list VPN10-VPN20
vpn 10
!
Branch-2#
Branch-2#show run | sec "natpool1"
<SNIP>
ip nat pool natpool1 172.16.2.9 172.16.2.9 prefix-length 30
DC路由器路由狀態
路由表從DC路由器捕獲資訊。
如輸出所示,DC路由器能夠使用
post-NAT IP派生
SS-NAT pool (172.16.2.0和172.16.2.8)而不是實際的LAN IP來區分兩個分支中的重疊IP地址,
192.168.10.0/24
172.31.31.1 且
172.31.31.2 是為Branch-1/Branch-2配
system-ip 置的。System-IP
172.31.31.10 屬於
vSmart。
DC-RTR#show ip route vrf 10
Routing Table: 10
<SNIP>
m 172.16.2.0 [251/0] via 172.31.31.1, 02:44:25, Sdwan-system-intf
m 172.16.2.8 [251/0] via 172.31.31.2, 02:43:33, Sdwan-system-intf
m 192.168.10.0[251/0] via 172.31.31.2, 03:01:35, Sdwan-system-intf
[251/0] via 172.31.31.1, 03:01:35, Sdwan-system-intf
DC-RTR#show sdwan omp routes
<SNIP> PATH ATTRIBUTE
VPN PREFIX FROM PEER ID LABEL STATUS TYPE TLOC IP COLOR ENCAP PREFERENCE
--------------------------------------------------------------------------------------------------------------------------------------
10 172.16.2.0/30 172.31.31.10 6 1002 C,I,R installed 172.31.31.1 mpls ipsec -
172.31.31.10 10 1002 Inv,U installed 172.31.31.1 biz-internet ipsec -
10 172.16.2.8/30 172.31.31.10 8 1002 C,I,R installed 172.31.31.2 mpls ipsec -
10 192.168.10.0/24 172.31.31.10 1 1002 C,I,R installed 172.31.31.1 mpls ipsec -
172.31.31.10 2 1002 C,I,R installed 172.31.31.2 mpls ipsec -
172.31.31.10 12 1002 Inv,U installed 172.31.31.1 biz-internet ipsec -
驗證
目前沒有適用於此組態的具體驗證程式。
疑難排解
目前尚無適用於此組態的具體疑難排解資訊。
其他資訊
案例1
在控制器使用版本20.3.4,而cEdge使用相同配置運行17.3.3a或更低版本的情況下,可以觀察到,在正常/故障轉移情況下,流量被NAT連線到服務端NAT池,並中斷流量。
cEdge擷取:
Host-BR-1#ping 192.0.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.100, timeout is 2 seconds:
U.U.U
Success rate is 0 percent (0/5)
Host-BR-1#
Branch-1#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 172.16.2.1:3 192.168.10.1:3 192.0.2.100:3 192.0.2.100:3
Total number of translations: 1
Branch-1#
WOW-Branch-1#show run | sec "natpool1"
<SNIP>
ip nat pool natpool1 172.16.2.1 172.16.2.2 prefix-length 30
從17.3.3a版上運行的cEdge捕獲輸出。透過SIG隧道發往的流量透過NAT轉換到SS-NAT池並被丟棄。從17.3.6版開始提供修復。
案例2
需求(含UTD檢查的服務端NAT (SS-NAT))
假設使用者已要求下列需求:
1. 當網際網路和MPLS傳輸均正常運行時,VPN 10中的無線客戶端可以定向到資料中心中的ISE進行身份驗證。此外,透過SD-WAN重疊傳輸的VPN 10流量可以接受檢查。由於此流量是重疊的一部分,VPN 10使用SS-NAT功能。[UTD + SS-NAT]
2. 如果網際網路傳輸不可用,來自VPN 10的所有流量(包括無線和有線流量)都可以使用MPLS傳輸透過重疊進行路由。此流量也可能會受到檢查。[UTD + SS-NAT]
這些要求旨在確保Branch-1中VPN 10在不同網路條件下安全且受監控的流量。
在上述兩種場景中,您都使用帶有SS-NAT組合的UTD檢測。以下是此方案的UTD配置示例。
policy utd-policy-vrf-10
all-interfaces
vrf 10
threat-inspection profile TEST_IDS_Policy
exit
警告:請注意,當前不支援將UTD與SS-NAT組合。因此,此組合併不如預期般有效。未來發行版本中可能會包含此問題的修正程式。
因應措施
解決方法是停用重疊IP VPN上的UTD策略(在本例中為VPN 10)並啟用全局VPN。
注意:此配置已在17.6版本中經過測試和驗證。
policy utd-policy-vrf-global
all-interfaces
vrf global
threat-inspection profile TEST_IDS_Policy
exit
修訂 | 發佈日期 | 意見 |
---|---|---|
1.0 |
09-Oct-2023 |
初始版本 |