OTV を使うと L2 延伸を行うことが出来ます。例えば、離れたデータセンター間で仮想マシンを vMotion した際等に利用出来ます。L2延伸だけなら L2TP でも可能ですが、L2TP ではループする可能性があります。対して OTV はマルチパス機能やループフリーである、という性質を持っています。今回はシンプルな構成で OTV を試してみます。
構成
以下の構成で検証します。
DC1 と DC2 という異なるデータセンターの OTV ルータ間でユニキャストを使った OTV 設定をしていますので、DC1 と DC2 の LAN 内が同じ 192.168.200.0/24 (VLAN200) というネットワークになっています。各ルータの OS は以下の通りです。
| Hostname | OS |
|---|---|
| DC1-OTV | IOS-XE 03.17.00 |
| DC2-OTV | IOS-XE 03.17.00 |
| Core | 15.6(2)T |
| DC1-Host | 15.6(2)T |
| DC2-Host | 15.6(2)T |
コンフィグ
Host と Core はインターフェイスにアドレスを割り当てているだけで、その他は特に何も設定していません。
DC1-OTV
hostname DC1-OTV ! otv site bridge-domain 100 otv isis hello-interval 3 ! otv site-identifier 0000.0000.0001 ! interface Overlay0 no ip address no shutdown otv join-interface GigabitEthernet2 otv adjacency-server unicast-only otv isis hello-interval 3 service instance 200 ethernet encapsulation dot1q 200 bridge-domain 200 ! interface GigabitEthernet2 ip address 10.0.1.1 255.255.255.0 no shutdown ! interface GigabitEthernet3 no ip address no shutdown service instance 100 ethernet encapsulation dot1q 100 bridge-domain 100 service instance 200 ethernet encapsulation dot1q 200 bridge-domain 200 ! ip route 10.0.2.0 255.255.255.0 10.0.1.254 ! end
DC2-OTV
hostname DC2-OTV ! otv site bridge-domain 100 otv isis hello-interval 3 ! otv site-identifier 0000.0000.0002 ! interface Overlay0 no ip address no shutdown otv join-interface GigabitEthernet2 otv use-adjacency-server 10.0.1.1 unicast-only otv adjacency-server unicast-only otv isis hello-interval 3 service instance 200 ethernet encapsulation dot1q 200 bridge-domain 200 ! interface GigabitEthernet2 ip address 10.0.2.2 255.255.255.0 no shutdown ! interface GigabitEthernet3 no ip address no shutdown service instance 100 ethernet encapsulation dot1q 100 bridge-domain 100 service instance 200 ethernet encapsulation dot1q 200 bridge-domain 200 ! ip route 10.0.1.0 255.255.255.0 10.0.2.254 ! end
Core
hostname Core ! interface GigabitEthernet0/1 ip address 10.0.1.254 255.255.255.0 no shutdown ! interface GigabitEthernet0/2 ip address 10.0.2.254 255.255.255.0 no shutdown ! end
DC1-Host
hostname DC1-Host ! interface GigabitEthernet0/1 no ip address no shutdown ! interface GigabitEthernet0/1.200 encapsulation dot1Q 200 ip address 192.168.200.11 255.255.255.0 ! end
DC2-Host
hostname DC2-Host ! interface GigabitEthernet0/1 no ip address no shutdown ! interface GigabitEthernet0/1.200 encapsulation dot1Q 200 ip address 192.168.200.22 255.255.255.0 ! end
状態確認
DC1-Host から DC2-Host へ Ping を実行
DC1-Host# ping 192.168.200.22 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.200.22, timeout is 2 seconds: ..!!! Success rate is 60 percent (3/5), round-trip min/avg/max = 9/10/12 ms
DC1-Host# show ip arp Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.200.11 - fa16.3e2f.8da1 ARPA GigabitEthernet0/1.200 Internet 192.168.200.22 7 fa16.3ee5.aae6 ARPA GigabitEthernet0/1.20
DC1-OTV の状態
DC1-OTV# show otv Overlay Interface Overlay0 VPN name : None VPN ID : 1 State : UP Fwd-capable : Yes Fwd-ready : Yes AED-Server : Yes Backup AED-Server : No AED Capable : Yes Join interface(s) : GigabitEthernet2 Join IPv4 address : 10.0.1.1 Tunnel interface(s) : Tunnel0 Encapsulation format : GRE/IPv4 Site Bridge-Domain : 100 Capability : Unicast-only Is Adjacency Server : Yes Adj Server Configured : No Prim/Sec Adj Svr(s) : None
DC1-OTV# show otv site Site Adjacency Information (Site Bridge-Domain: 100) Overlay0 Site-Local Adjacencies (Count: 1) Hostname System ID Last Change Ordinal AED Enabled Status * DC1-OTV 001E.7A3B.C900 01:43:25 0 site overlay
DC1-OTV# show otv vlan Key: SI - Service Instance, NA - Non AED, NFC - Not Forward Capable. Overlay 0 VLAN Configuration Information Inst VLAN BD Auth ED State Site If(s) 0 200 200 *DC1-OTV active Gi3:SI200 Total VLAN(s): 1
DC1-OTV# show otv adjacency Overlay Adjacency Database for overlay 0 Hostname System-ID Dest Addr Site-ID Up Time State DC2-OTV 001e.e681.fd00 10.0.2.2 0000.0000.0002 01:41:38 UP
DC1-OTV# show otv arp-nd-cache Overlay0 ARP/ND L3->L2 Address Mapping Cache BD MAC Layer-3 Address Age (HH:MM:SS) Local/Remote 200 fa16.3ee5.aae6 192.168.200.22 00:00:34 Remote
DC1-OTV# show otv route
Codes: BD - Bridge-Domain, AD - Admin-Distance,
SI - Service Instance, * - Backup Route
OTV Unicast MAC Routing Table for Overlay0
Inst VLAN BD MAC Address AD Owner Next Hops(s)
----------------------------------------------------------
0 200 200 fa16.3e2f.8da1 40 BD Eng Gi3:SI200
0 200 200 fa16.3ee5.aae6 50 ISIS DC2-OTV
2 unicast routes displayed in Overlay0
----------------------------------------------------------
2 Total Unicast Routes Displayed
DC2-OTV の状態
DC2-OTV# show otv Overlay Interface Overlay0 VPN name : None VPN ID : 1 State : UP Fwd-capable : Yes Fwd-ready : Yes AED-Server : Yes Backup AED-Server : No AED Capable : Yes Join interface(s) : GigabitEthernet2 Join IPv4 address : 10.0.2.2 Tunnel interface(s) : Tunnel0 Encapsulation format : GRE/IPv4 Site Bridge-Domain : 100 Capability : Unicast-only Is Adjacency Server : Yes Adj Server Configured : Yes Prim/Sec Adj Svr(s) : 10.0.1.1
DC2-OTV# show otv site Site Adjacency Information (Site Bridge-Domain: 100) Overlay0 Site-Local Adjacencies (Count: 1) Hostname System ID Last Change Ordinal AED Enabled Status * DC2-OTV 001E.E681.FD00 01:46:12 0 site overlay
DC2-OTV# show otv vlan Key: SI - Service Instance, NA - Non AED, NFC - Not Forward Capable. Overlay 0 VLAN Configuration Information Inst VLAN BD Auth ED State Site If(s) 0 200 200 *DC2-OTV active Gi3:SI200 Total VLAN(s): 1
DC2-OTV# show otv adjacency Overlay Adjacency Database for overlay 0 Hostname System-ID Dest Addr Site-ID Up Time State DC1-OTV 001e.7a3b.c900 10.0.1.1 0000.0000.0001 01:46:54 UP
DC2-OTV# show otv arp-nd-cache Overlay0 ARP/ND L3->L2 Address Mapping Cache BD MAC Layer-3 Address Age (HH:MM:SS) Local/Remote 200 fa16.3e2f.8da1 192.168.200.11 00:04:58 Remote
DC2-OTV# show otv route
Codes: BD - Bridge-Domain, AD - Admin-Distance,
SI - Service Instance, * - Backup Route
OTV Unicast MAC Routing Table for Overlay0
Inst VLAN BD MAC Address AD Owner Next Hops(s)
----------------------------------------------------------
0 200 200 fa16.3e2f.8da1 50 ISIS DC1-OTV
0 200 200 fa16.3ee5.aae6 40 BD Eng Gi3:SI200
2 unicast routes displayed in Overlay0
----------------------------------------------------------
2 Total Unicast Routes Displayed
DC2-Host での状態確認
DC2-Host# show ip arp Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.200.11 7 fa16.3e2f.8da1 ARPA GigabitEthernet0/1.200 Internet 192.168.200.22 - fa16.3ee5.aae6 ARPA GigabitEthernet0/1.20