L2 VPN Lab：
验证 R1 / R2 之间是否正常，可以先给 R2 配上地址验证正常后在删除 IP Address
Like-to-Like模式
1、AS 100 IGP
2、AS 100 LDP
3、将 R1 / R2 和 R4 / R7 之间的”附接电路 / AC“通过 AS 100 的伪线绑定（AC：Attachment Circuit）
（R2 上的串口和 R4 上的 PPP 链路接口连接起来的链路就叫做“伪线 / pseudowire”）
r2(config-if)#xconnect 4.4.4.4 100 encapsulation mpls（标亮的两端 VC-ID 一定要相等）
r4(config-if)#xconnect 2.2.2.2 100 encapsulation mpls
r2#ping mpls pseudowire 4.4.4.4 100（用于测试伪线是否连通）
r2#show mpls ldp neighbor
r2#show mpls ldp neighbor
Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0
TCP connection: 3.3.3.3.42301 - 2.2.2.2.646
State: Oper; Msgs sent/rcvd: 13/13; Downstream
Up time: 00:04:35
LDP discovery sources:
Ethernet0/0.23, Src IP addr: 23.1.1.3
Addresses bound to peer LDP Ident:
23.1.1.3 34.1.1.3 3.3.3.3
Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 2.2.2.2:0
TCP connection: 4.4.4.4.27411 - 2.2.2.2.646
State: Oper; Msgs sent/rcvd: 11/11; Downstream
Up time: 00:02:14
LDP discovery sources:
Targeted Hello 2.2.2.2 -> 4.4.4.4, active, passive
Addresses bound to peer LDP Ident:
34.1.1.4 4.4.4.4
r2#show mpls l2transport vc 100 detail（查看伪线的标签压制情况，也可以是 Data-Plane 的标签压制情况）
r2#show mpls l2transport vc 100 detail
Local interface: Se1/1 up, line protocol up, PPP up
Destination address: 4.4.4.4, VC ID: 100, VC status: up
Output interface: Et0/0.23, imposed label stack {3001 4003}
Preferred path: not configured
Default path: active
Next hop: 23.1.1.3
Create time: 00:21:06, last status change time: 00:21:05
Signaling protocol: LDP, peer 4.4.4.4:0 up
Targeted Hello: 2.2.2.2(LDP Id) -> 4.4.4.4
Status TLV support (local/remote) : enabled/supported
Label/status state machine : established, LruRru
Last local dataplane status rcvd: no fault
Last local SSS circuit status rcvd: no fault
Last local SSS circuit status sent: no fault
Last local LDP TLV status sent: no fault
Last remote LDP TLV status rcvd: no fault
MPLS VC labels: local 2003, remote 4003
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description:
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 282, send 282
--More--
r2#show mpls l2transport binding（查看 L2 VPN 标签）
r2#show mpls l2transport binding
Destination Address: 4.4.4.4, VC ID: 100
Local Label: 2003
Cbit: 1, VC Type: PPP, GroupID: 0
MTU: 1500, Interface Desc: n/a
VCCV: CC Type: CW [1], RA [2]
CV Type: LSPV [2]
Remote Label: 4003
Cbit: 1, VC Type: PPP, GroupID: 0
MTU: 1500, Interface Desc: n/a
VCCV: CC Type: CW [1], RA [2]
CV Type: LSPV [2]
Any-to-Any 模式（实现不同接入介质的通信）
1、全局定义伪线，并指定伪线中可以交互的信息
r2(config)#pseudowire-class T6
r2(config-pw-class)#encapsulation mpls
r2(config-pw-class)#interworking ip （注明伪线两端只交换 IP 信息，所以 CE 之间封装可以不同）
r4(config)#pseudowire-class T2
r4(config-pw-class)#encapsulation mpls
r4(config-pw-class)#interworking ip
2、接口调用伪线
r2(config-subif)#xconnect 4.4.4.4 200 pw-class T6
r4(config)#connect xxx serial 1/0 405 l2transport （帧中继的配置比较特殊）
r4(config-fr-pw-switching)#xconnect 2.2.2.2 200 pw-class T2
r4(config-if)#encapsulation frame-relay
r4(config-if)#no frame-relay inverse-arp
由于使用 Any-to-Any 模式后，interworking ip 命令指定了只能交互“IP”信息，所以从 r6 发往 r5 的以太帧会自动给拆除“Ethernet”头部封装信息，而不是像传统的“TCP / IP 协议栈”一样解封装
