玩转华为ENSP模拟器系列 | 配置动态BFD检测LDP LSP示例

Posted 2022-05-11 COCOgsta

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目标

介绍配置动态BFD检测LDP LSP的配置过程，包括在各设备以及各接口使能MPLS、MPLS LDP，以及在源端和宿端上使能BFD能力。

组网需求

MPLS LDP越来越多的应用在运营商的网络中，运营商对MPLS LDP网路可靠性要求也越来越高，BFD for LDP能够为LDP LSP提供快速的检测机制，当网络发生故障时，BFD能够被快速感知故障同时触发LSP流量进行切换。BFD for LDP常和LDP FRR技术联用。

如图1所示，节点PE1、P1、P2和PE2属于同一MPLS域，PE1和PE2之间创建主备LDP LSP，要求使用动态BFD检测LDP LSP的连通性。

配置思路

• 按照图1所示配置各LSR上的接口IP地址。

• 配置OSPF协议通告各个接口的IP地址，使得各设备间能够互通。调整接口的Cost值，使PE1–P1–PE2成为主路径，PE1–P2–PE2成为备份路径。

• 配置LDP LSP，各节点针对所有路由触发建立LSP。

• 配置LDP Auto FRR，使得PE1和PE2之间生成备份LSP。

• 配置动态BFD for LDP，通过FEC列表触发建立BFD会话。

操作步骤

1. 配置各接口的IP地址

根据图1配置接口IP地址，并在节点上创建Loopback接口。具体配置过程请参见配置文件。

1. 配置OSPF

在各个节点上配置OSPF，使各设备间网络能互通。具体配置过程请参见配置文件。

1. 配置LDP LSP

在各个节点上配置MPLS LDP，触发LDP针对所有路由建立LSP。具体配置过程请参见配置文件。

1. 配置LDP Auto FRR

在PE1上使能OSPF FRR以及LDP Auto FRR。

PE1:
ospf 1
 frr
  loop-free-alternate
mpls ldp
  auto-frr lsp-trigger all

在PE2上使能OSPF FRR以及LDP Auto FRR。

PE2:
ospf 1
 frr
  loop-free-alternate
mpls ldp
  auto-frr lsp-trigger all

1. 配置动态BFD会话检测LDP LSP

在PE1上使能BFD，指定动态触发BFD会话的FEC列表，配置主机路由触发策略，并调整BFD检测参数。

PE1:
bfd
 mpls-passive
fec-list 11
 fec-node 4.4.4.4
mpls
 mpls bfd enable
 mpls bfd-trigger fec-list 11
 mpls bfd min-tx-interval 100 min-rx-interval 600 detect-multiplier 4

在PE2上使能BFD，指定动态触发BFD会话的FEC列表，配置主机路由触发策略，并调整BFD检测参数。

PE2:
bfd
 mpls-passive
fec-list 12
 fec-node 1.1.1.1
mpls
 mpls bfd enable
 mpls bfd-trigger fec-list 12
 mpls bfd min-tx-interval 100 min-rx-interval 600 detect-multiplier 4

1. 检查配置结果

执行display bfd session all verbose命令查看动态创建的BFD会话状态。

[~PE1-mpls]dis bfd session all verbose 
(w): State in WTR
(*): State is invalid
--------------------------------------------------------------------------------
  State : Up                    Name : dyn_16387
--------------------------------------------------------------------------------
  Local Discriminator    : 16387            Remote Discriminator   : 16391 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : LDP_LSP 
  Bind Session Type      : Dynamic  
  Bind Peer IP Address   : 4.4.4.4         
  NextHop Ip Address     : 10.1.2.2  
  Bind Interface         : Ethernet1/0/1                                    
  Tunnel ID              : -  
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 100              Min Rx Interval (ms)   : 600 
  Actual Tx Interval (ms): 100              Actual Rx Interval (ms): 600 
  Local Detect Multi     : 4                Detect Interval (ms)   : 1800 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 3784             TTL                    : 1 
  Proc Interface Status  : Disable          Process PST            : Enable     
  WTR Interval (ms)      : -                Config PST             : Enable     
  Active Multi           : 3   
  Last Local Diagnostic  : Neighbor Signaled Session Down(Receive AdminDown)
  Bind Application       : LDP
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
  State : Up                    Name : dyn_16388
--------------------------------------------------------------------------------
  Local Discriminator    : 16388            Remote Discriminator   : 16392 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : LDP_LSP 
  Bind Session Type      : Dynamic  
  Bind Peer IP Address   : 4.4.4.4         
  NextHop Ip Address     : 10.1.1.2  
  Bind Interface         : Ethernet1/0/0                                    
  Tunnel ID              : -  
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 100              Min Rx Interval (ms)   : 600 
  Actual Tx Interval (ms): 100              Actual Rx Interval (ms): 600 
  Local Detect Multi     : 4                Detect Interval (ms)   : 1800 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 3784             TTL                    : 1 
  Proc Interface Status  : Disable          Process PST            : Enable     
  WTR Interval (ms)      : -                Config PST             : Enable     
  Active Multi           : 3   
  Last Local Diagnostic  : Neighbor Signaled Session Down(Receive AdminDown)
  Bind Application       : LDP
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
  (Multi Hop) State : Up                    Name : dyn_16389
--------------------------------------------------------------------------------
  Local Discriminator    : 16389            Remote Discriminator   : 16393 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer IP Address  
  Bind Session Type      : Entire_Dynamic  
  Bind Peer IP Address   : 4.4.4.4          
  Bind Interface         : -                                                 
  Track Interface        : - 
  Bind Source IP Address : 1.1.1.1   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 3                Min Rx Interval (ms)   : 3 
  Actual Tx Interval (ms): 600              Actual Rx Interval (ms): 100 
  Local Detect Multi     : 3                Detect Interval (ms)   : 400 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 4784             TTL                    : 253 
  Proc Interface Status  : Disable          Process PST            : Disable    
  WTR Interval (ms)      : -                Config PST             : Disable    
  Active Multi           : 4   
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
  (Multi Hop) State : Up                    Name : dyn_16390
--------------------------------------------------------------------------------
  Local Discriminator    : 16390            Remote Discriminator   : 16394 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer IP Address  
  Bind Session Type      : Entire_Dynamic  
  Bind Peer IP Address   : 4.4.4.4          
  Bind Interface         : -                                                 
  Track Interface        : - 
  Bind Source IP Address : 1.1.1.1   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 3                Min Rx Interval (ms)   : 3 
  Actual Tx Interval (ms): 600              Actual Rx Interval (ms): 100 
  Local Detect Multi     : 3                Detect Interval (ms)   : 400 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 4784             TTL                    : 253 
  Proc Interface Status  : Disable          Process PST            : Disable    
  WTR Interval (ms)      : -                Config PST             : Disable    
  Active Multi           : 4   
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
    Total UP/DOWN Session Number : 4/0
[~PE1-mpls]  

查看PE2上的被动创建的BFD会话状态，其中BFD Bind Type字段的值为“Peer IP Address”，说明PE2发送的BFD报文是通过IP路由传输的。

[~PE2-mpls]dis bfd session passive-dynamic verbose 
(w): State in WTR
(*): State is invalid
--------------------------------------------------------------------------------
  (Multi Hop) State : Up                    Name : dyn_16391
--------------------------------------------------------------------------------
  Local Discriminator    : 16391            Remote Discriminator   : 16387 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer IP Address  
  Bind Session Type      : Entire_Dynamic  
  Bind Peer IP Address   : 1.1.1.1          
  Bind Interface         : -                                                 
  Track Interface        : - 
  Bind Source IP Address : 4.4.4.4   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 3                Min Rx Interval (ms)   : 3 
  Actual Tx Interval (ms): 600              Actual Rx Interval (ms): 100 
  Local Detect Multi     : 3                Detect Interval (ms)   : 400 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 4784             TTL                    : 253 
  Proc Interface Status  : Disable          Process PST            : Disable    
  WTR Interval (ms)      : -                Config PST             : Disable    
  Active Multi           : 4   
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
  (Multi Hop) State : Up                    Name : dyn_16392
--------------------------------------------------------------------------------
  Local Discriminator    : 16392            Remote Discriminator   : 16388 
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer IP Address  
  Bind Session Type      : Entire_Dynamic  
  Bind Peer IP Address   : 1.1.1.1          
  Bind Interface         : -                                                 
  Track Interface        : - 
  Bind Source IP Address : 4.4.4.4   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 3                Min Rx Interval (ms)   : 3 
  Actual Tx Interval (ms): 600              Actual Rx Interval (ms): 100 
  Local Detect Multi     : 3                Detect Interval (ms)   : 400 
  Echo Passive           : Disable          Acl Number             : - 
  Destination Port       : 4784             TTL                    : 253 
  Proc Interface Status  : Disable          Process PST            : Disable    
  WTR Interval (ms)      : -                Config PST             : Disable    
  Active Multi           : 4   
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : -                Session Detect TmrID   : - 
  Session Init TmrID     : -                Session WTR TmrID      : - 
  Session Echo Tx TmrID  : -   
  Session Description    : - 
--------------------------------------------------------------------------------
    Total UP/DOWN Session Number : 2/0
[~PE2-mpls]  

PE1->PE2，走MPLS标签

PE2->PE1，走IP路由