网络工程 - 瞻博网络 MX 中基于 LDP 的 VPLS 连接中的 PE 路由关闭 - 吾爱随笔录

我在瞻博网络 MX 上针对基于 LDP 的 VPLS 连接观察“PE route down message”。IGP 协议是 IS-IS。LDP VPLS 连接是点对点的（只有两个端点）。

当我使用扩展旋钮检查某些实例的 LDP VPLS 状态时，它会在连接历史记录中显示“PE route down”以及“status update timer”。有人可以解释一下这是什么意思吗？在日志消息中还观察到 VPLS 连接从上到下然后再上。

下面是一些观察

当我们在路由表中检查到 LDP 对等 ip（目标会话）的路由时，inet.0 中的路由年龄比 inet.3 中的“更多”。

与目标对等方的 LDP 会话不抖动。

以下是配置和日志。

R1> show configuration routing-instances 1784 
instance-type vpls;
interface ge-2/1/5.1784;
protocols {
    vpls {
        encapsulation-type ethernet-vlan;
        no-tunnel-services;
        vpls-id 1784;
        mtu 1500;
        neighbor 192.168.0.18;
    }
}



R1> show vpls connections instance 1784 extensive 
Instance: 1784
      VPLS-id: 1784
        Number of local interfaces: 1
        Number of local interfaces up: 1
        ge-2/1/5.1784      
        lsi.1097220                   Intf - vpls 1784 neighbor 192.168.0.18 vpls-id 1784
        Neighbor                  Type  St     Time last up          # Up trans
        192.168.0.18(vpls-id 1784) rmt  Up     May 14 11:14:20 2019        1196
          Remote PE: 192.168.0.18, Negotiated control-word: No
          Incoming label: 262190, Outgoing label: 153422
          Negotiated PW status TLV: No
          Local interface: lsi.1097220, Status: Up, Encapsulation: VLAN
            Description: Intf - vpls 1784 neighbor 192.168.0.18 vpls-id 1784
          Flow Label Transmit: No, Flow Label Receive: No
        Connection History:                 
            May 14 11:14:20 2019  status update timer  
            May 14 11:14:20 2019  PE route down        
            May 14 11:14:15 2019  status update timer  
            May 14 11:14:14 2019  PE route down        
            May 14 10:14:20 2019  status update timer  
            May 14 10:14:20 2019  PE route down        
            May 14 10:14:15 2019  status update timer  
            May 14 10:14:14 2019  PE route down        
            May 14 09:19:43 2019  status update timer  
            May 14 09:19:42 2019  PE route down        
            May 14 09:19:38 2019  status update timer  
            May 14 09:19:36 2019  PE route down        
            May 14 09:14:20 2019  status update timer  
            May 14 09:14:20 2019  PE route down        
            May 14 09:14:15 2019  status update timer  
            May 14 09:14:14 2019  PE route down        
            May 14 08:14:20 2019  status update timer  
            May 14 08:14:20 2019  PE route down        
            May 14 08:14:15 2019  status update timer  
            May 14 08:14:14 2019  PE route down 

R1> show route 192.168.0.18 

inet.0: 47621 destinations, 141466 routes (47621 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

192.168.0.18/32    *[IS-IS/18] 02:53:29, metric 149
                    > to 192.168.7.14 via ae0.3
                      to 192.168.7.18 via ae15.3

inet.3: 262 destinations, 262 routes (262 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

192.168.0.18/32    *[LDP/9] 00:58:42, metric 149
                    > to 192.168.7.14 via ae0.3, Push 50294
                      to 192.168.7.18 via ae15.3, Push 670023

R1> show ldp session 192.168.0.18 detail 
Address: 192.168.0.18, State: Operational, Connection: Open, Hold time: 29
  Session ID: 192.168.1.35:0--192.168.0.18:0
  Next keepalive in 9 seconds
  Passive, Maximum PDU: 4096, Hold time: 30, Neighbor count: 1
  Neighbor types: configured-layer2
  Keepalive interval: 10, Connect retry interval: 1
  Local address: 192.168.1.35, Remote address: 192.168.0.18
  Up for 3w4d 07:43:50

日志消息如下所示：-

May 14 11:14:14.419 2019  R1 rpd[9997]: %DAEMON-5-RPD_LAYER2_VC_DOWN: State of Layer 2 VC (Neighbor : 192.168.0.18, VC-ID : 1784) changed from UP to VC-Dn
May 14 11:14:15.891 2019  R1 rpd[9997]: %DAEMON-6-RPD_LAYER2_VC_UP: State of Layer 2 VC (Neighbor : 192.168.0.18, VC-ID : 1784) changed to UP
May 14 11:14:20.085 2019  R1 rpd[9997]: %DAEMON-5-RPD_LAYER2_VC_DOWN: State of Layer 2 VC (Neighbor : 192.168.0.18, VC-ID : 1784) changed from UP to VC-Dn
May 14 11:14:20.688 2019  R1 rpd[9997]: %DAEMON-6-RPD_LAYER2_VC_UP: State of Layer 2 VC (Neighbor : 192.168.0.18, VC-ID : 1784) changed to UP