R7設定
pseudowire-class test
encapsulation l2tpv3
ip local interface Ethernet0/0
interface Ethernet0/1
no ip address
xconnect 1.1.1.2 1 encapsulation l2tpv3 pw-class test
R9設定
pseudowire-class test1111
encapsulation l2tpv3
ip local interface Ethernet0/0
interface Ethernet0/1
no ip address
xconnect 1.1.1.1 1 encapsulation l2tpv3 pw-class test1111
在R7與R9輸入show xconnect all
Legend: XC ST=Xconnect State S1=Segment1 State S2=Segment2 State
UP=Up DN=Down AD=Admin Down IA=Inactive
SB=Standby HS=Hot Standby RV=Recovering NH=No Hardware
XC ST Segment 1 S1 Segment 2 S2
------+---------------------------------+--+---------------------------------+--
UP pri ac Et0/1:4(Ethernet) UP l2tp 1.1.1.2:1 UP
Legend: XC ST=Xconnect State S1=Segment1 State S2=Segment2 State
UP=Up DN=Down AD=Admin Down IA=Inactive
SB=Standby HS=Hot Standby RV=Recovering NH=No Hardware
XC ST Segment 1 S1 Segment 2 S2
------+---------------------------------+--+---------------------------------+--
UP pri ac Et0/1:4(Ethernet) UP l2tp 1.1.1.1:1 UP
以及在R7與R9輸入show L2tun tunnel all
L2TP Tunnel Information Total tunnels 1 sessions 1
Tunnel id 1977738540 is up, remote id is 1914104780, 1 active sessions
Remotely initiated tunnel
Tunnel state is established, time since change 00:09:43
Tunnel transport is IP (115)
Remote tunnel name is Router
Internet Address 1.1.1.2, port 0
Local tunnel name is Router
Internet Address 1.1.1.1, port 0
L2TP class for tunnel is l2tp_default_class
Counters, taking last clear into account:
81 packets sent, 81 received
8795 bytes sent, 8795 received
Last clearing of counters never
Counters, ignoring last clear:
81 packets sent, 81 received
8795 bytes sent, 8795 received
Control Ns 12, Nr 5
Local RWS 1024 (default), Remote RWS 1024
Control channel Congestion Control is disabled
Tunnel PMTU checking disabled
Retransmission time 1, max 1 seconds
Unsent queuesize 0, max 0
Resend queuesize 0, max 1
Total resends 0, ZLB ACKs sent 3
Total out-of-order dropped pkts 0
Total out-of-order reorder pkts 0
Total peer authentication failures 0
Current no session pak queue check 0 of 5
Retransmit time distribution: 0 0 0 0 0 0 0 0 0
Control message authentication is disabled
底下R8與R10就可以互通了。
需要注意→範例在R7 interface下xconnect指令，R9就一樣要在interface。
如果R7是使用vlan interface，那R9一樣要用vlan interface，也就是兩邊的interface type要一樣。
參考連結
https://www.byteworks.com/blog/layer-2-extensibility-options-for-business-networks/
https://www.cisco.com/c/zh_cn/support/docs/ip/layer-two-tunnel-protocol-l2tp/116266-configure-l2-00.html
https://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/l2tpv325.html
