玩转华为ENSP模拟器系列 | 配置静态BFD for IS-IS特性示例

Posted 2022-05-09 COCOgsta

素材来源：华为路由器配置指南

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目标

介绍静态BFD for IS-IS的配置过程，包括配置BFD参数和使能静态BFD。

组网需求

DeviceA和DeviceB之间采用二层交换机相连。

DeviceA、DeviceB和DeviceC之间运行IS-IS。

使用BFD检测DeviceA和DeviceB的IS-IS邻居关系。当DeviceA和DeviceB之间的链路发生故障时，BFD能够快速检测到故障并通告给IS-IS协议。

配置思路

• 在各路由器上使能IS-IS基本功能。

• 在DeviceA和DeviceB上使能BFD检测机制。

操作步骤

1. 配置各路由器接口的IP地址（略）
2. 配置IS-IS基本功能

配置DeviceA。

DeviceA:
isis 1
 is-level level-2
 network-entity aa.1111.1111.1111.00
interface Ethernet1/0/0
 isis enable 1 

配置DeviceB。

DeviceB:
isis 1
 is-level level-2
 network-entity aa.2222.2222.2222.00
interface Ethernet1/0/0
 isis enable 1  
interface Ethernet1/0/1
 isis enable 1

配置DeviceC。

DeviceC:
isis 1
 is-level level-2
 network-entity aa.3333.3333.3333.00
interface Ethernet1/0/0
 isis enable 1  

配置完成后，可以看到DeviceA与DeviceB建立了邻居关系。

[~DeviceA]dis isis peer
                          Peer information for ISIS(1)
                         
  System Id     Interface          Circuit Id        State HoldTime Type     PRI
--------------------------------------------------------------------------------
2222.2222.2222  Eth1/0/0           2222.2222.2222.02  Up   9s       L2       64 
Total Peer(s): 1
[~DeviceA] 

DeviceA的IS-IS路由表中有去往DeviceB和DeviceC的表项。

[~DeviceA]dis isis route
                         Route information for ISIS(1)
                         -----------------------------
                        ISIS(1) Level-2 Forwarding Table
                        --------------------------------
IPV4 Destination   IntCost    ExtCost ExitInterface     NextHop         Flags
-------------------------------------------------------------------------------
10.1.1.0/24        10         NULL    Eth1/0/0          Direct          D/-/L/-
10.2.1.0/24        20         NULL    Eth1/0/0          10.1.1.2        A/-/-/-
     Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut, 
            U-Up/Down Bit Set, LP-Local Prefix-Sid
[~DeviceA]

1. 配置BFD

在DeviceA上使能BFD，并配置BFD Session。

DeviceA:
bfd
bfd atob bind peer-ip 10.1.1.2 interface Ethernet1/0/0
 discriminator local 1
 discriminator remote 2

在DeviceB上使能BFD，并配置BFD Session。

DeviceB:
bfd
bfd btoa bind peer-ip 10.1.1.1 interface Ethernet1/0/1
 discriminator local 2
 discriminator remote 1

配置完成后，在DeviceA或DeviceB上执行display bfd session命令，可以看到BFD Session的状态为Up。

以DeviceA的显示为例。

[~DeviceA]dis bfd session all
(w): State in WTR
(*): State is invalid
--------------------------------------------------------------------------------
Local      Remote     PeerIpAddr      State     Type        InterfaceName 
--------------------------------------------------------------------------------
1          2          10.1.1.2        Up        S_IP_IF     Ethernet1/0/0
--------------------------------------------------------------------------------
    Total UP/DOWN Session Number : 1/0
[~DeviceA]

1. 使能IS-IS的快速感知功能

配置DeviceA。

DeviceA:
interface Ethernet1/0/0
 isis bfd static

配置DeviceB。

DeviceB:
interface Ethernet1/0/1
 isis bfd static

1. 检查配置结果

在DeviceA上打开调试信息开关。

<DeviceA>debugging isis adjacency 
<DeviceA>debugging isis circuit-information 
<DeviceA>terminal debugging 
<DeviceA>terminal monitor

对DeviceB的GigabitEthernet1/0/0接口执行shutdown命令，模拟链路故障。

[~DeviceB-Ethernet1/0/1]shut
[*DeviceB-Ethernet1/0/1]commit

在DeviceA上可以看到以下日志信息，表明IS-IS根据BFD报告的故障删除了与DeviceB的邻居关系。

<DeviceA>
Dec 19 2019 16:48:40.063 DeviceA %%01ISIS/6/RX_LAN_IIH(d):CID=0x80890467;ISIS-1-ADJ: Received Lan Level-2 IIH. (IfName=Ethernet1/0/0, RemoteSnpa=38.60.aa.02.01.01)
Dec 19 2019 16:48:40.063 DeviceA %%01ISIS/6/LAN_ADJ_USAGE(d):CID=0x80890467;ISIS-1-ADJ: Set LAN ADJ usage to Level-2. (IfName=Ethernet1/0/0, CircLevel=2, PduCircType=2)
Dec 19 2019 16:48:43.074 DeviceA %%01ISIS/6/RX_LAN_IIH(d):CID=0x80890467;ISIS-1-ADJ: Received Lan Level-2 IIH. (IfName=Ethernet1/0/0, RemoteSnpa=38.60.aa.02.01.01)
Dec 19 2019 16:48:43.074 DeviceA %%01ISIS/6/LAN_ADJ_USAGE(d):CID=0x80890467;ISIS-1-ADJ: Set LAN ADJ usage to Level-2. (IfName=Ethernet1/0/0, CircLevel=2, PduCircType=2)
Dec 19 2019 16:48:44.267 DeviceA %%01ISIS/6/ADJ_DOWN(d):CID=0x80890467;ISIS-1-ADJ: ADJ state change to down, reason: ADJ IPv4 down. (IfName=Ethernet1/0/0, AdjSysId=2222.2222.2222, OldState=0, AdjUsage=2)
Dec 19 2019 16:48:44.267 DeviceA %%01ISIS/6/DIS_NO_UP_ADJ(d):CID=0x80890467;ISIS-1-DIS: DIS down, reason: circuit has no up adjacency. (IfName=Ethernet1/0/0, Level=2, DisIdLen=0, DrStatus=4)
Dec 19 2019 16:48:44.370 DeviceA %%01ISIS/6/TX_LAN_IIH(d):CID=0x80890467;ISIS-1-ADJ: Sending Lan Level-2 IIH. (IfName=Ethernet1/0/0, LocalSnpa=38.60.aa.01.01.00)
Dec 19 2019 16:48:44 DeviceA %%01BFD/4/STACHG_TODWN(l):CID=0x80740421;BFD session changed to Down. (SlotNumber=1, Discriminator=1, Diagnostic=DetectDown, Applications=No Application Bind, ProcessPST=False, BindInterfaceName=Ethernet1/0/0, InterfacePhysicalState=Up, InterfaceProtocolState=Up, TunnelName=-)
#24/active/isisAdjacencyChange/Major/occurredTime:2019-12-19 16:48:44/-/-/alarmID:0x0001009e/CID=0x80890467:ISIS adjacency state change. (SysInstance=1, SysLevel=2, CircIndex=1, CircIfIndex=6, LspId=2222.2222.2222.00.00, AdjState=1, IfIndex=6, IfName=Ethernet1/0/0, Reason=BFD detected that the neighbor went Down, SubReason=The BFD session went Down)
Dec 19 2019 16:48:44 DeviceA %%01ISIS/2/isisAdjacencyChange_active(l):CID=0x80890467-alarmID=0x0001009e;ISIS adjacency state change. (SysInstance=1, SysLevel=2, CircIndex=1, CircIfIndex=6, LspId=2222.2222.2222.00.00, AdjState=1, IfIndex=6, IfName=Ethernet1/0/0, Reason=BFD detected that the neighbor went Down, SubReason=The BFD session went Down)
Dec 19 2019 16:48:53.380 DeviceA %%01ISIS/6/TX_LAN_IIH(d):CID=0x80890467;ISIS-1-ADJ: Sending Lan Level-2 IIH. (IfName=Ethernet1/0/0, LocalSnpa=38.60.aa.01.01.00)