【H3C技术】配置IS-IS快速收敛

配置实例   组网需求    如下图所示。

 

路由器RouterA和RouterB之间运行IS-IS协议。

路由器RouterA和RouterB同属于区域10，都是Level-2路由器。

配置IS-IS快速收敛示例

 

配置思路
采用如下思路配置IS-IS快速收敛特性：

在各路由器上使能IS-IS基本功能。
在RouterA和RouterB上使能BFD检测机制。
在RouterA和RouterB上关闭hello报文填充。
在RouterA和RouterB上配置快速收敛时间参数。
数据准备
为完成此配置例，需准备如下的数据：

三台路由器的级别和所属区域号。
快速收敛时间参数值。
配置步骤
步骤 1     配置各路由器接口的IP地址（略）

步骤 2     配置IS-IS基本功能

# 配置RouterA。

[RouterA] isis 1

[RouterA-isis-1] is-level level-2

[RouterA-isis-1] network-entity 10.0000.0000.0001.00

[RouterA-isis-1] quit

[RouterA] interface GigabitEthernet 1/0/0

[RouterA- GigabitEthernet1/0/0] isis enable 1

[RouterA- GigabitEthernet1/0/0] quit

# 配置RouterB。

[RouterB] isis 1

[RouterB-isis-1] is-level level-2

[RouterB-isis-1] network-entity 10.0000.0000.0002.00

[RouterB-isis-1] quit

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] isis enable 1

[RouterB-GigabitEthernet1/0/0] quit

# 在RouterA上查看邻居状态和路由计算时间。

在RouterB的GE1/0/0端口上执行命令shutdown，模拟链路down掉。

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] shutdown

在RouterA上查看邻居信息。

<RouterA> debugging isis spf-summary

<RouterA> terminal debugging

<RouterA> terminal monitor

<RouterA> display isis peer

 

                          Peer information for ISIS(1)

                          ----------------------------

  System Id    Interface           Circuit Id          State HoldTime Type     PRI

0000.0000.0002 Ge1/0/0            0000.0000.0002.01    Up    7s        L2       64 

由于在RouterB的GE口上执行shutdown命令，系统会维持holdtime时间，并不马上宣告邻居失效，直到holdtime时间超时后才删除邻居，这时会激发路由计算。

*0.11042110 Quidway ISIS/7/ISIS:

  Prc job completed at Sec = 11019, MSec = 750.

 

*0.11042110 Quidway ISIS/7/ISIS:

  Signal SPF at Sec = 11042, MSec = 110.

 

*0.11052110 Quidway ISIS/7/ISIS:

  Signal SPF at Sec = 11042, MSec = 110.

 

*0.11052110 Quidway ISIS/7/ISIS:

  ISpf starts at Sec = 11052, MSec = 110.ISIS-1-SPF-STATS: RT Calculation: Elaps

ed time: 0 Milliseconds

 

*0.11052110 Quidway ISIS/7/ISIS:

 ISIS-1-SPF-PRC: Received L2 System Change Event for 0000.0000.0002.00, Change =

 2

 

*0.11052110 Quidway ISIS/7/ISIS:

 ISIS-1-SPF-PRC: Received L2 System Change Event for 0000.0000.0002.01, Change =

 2

 

*0.11052110 Quidway ISIS/7/ISIS:

 ISIS-1-DEC-PRC: Igorning pseudo-node system change information from the ISPF mo

dule.

 

*0.11052110 Quidway ISIS/7/ISIS:

 

 

*0.11052110 Quidway ISIS/7/ISIS:

  ISpf ends(and prc starts) at Sec = 11052, MSec = 110.

 

*0.11052110 Quidway ISIS/7/ISIS:

  Prc job starts to run at Sec = 11052, MSec = 110.ISIS-1-SPF-PRC: Processing L2

 LSPs of System :0000.0000.0002, Change Type = 2

在holdtime时间内，通过GE1/0/0接口的路由将被丢弃，导致报文不能正确送达。这时需要使能BFD特性和配置快速收敛时间参数，以保证在网络变化时，路由器可以迅速感知拓扑变化并重新计算路由。

步骤 3     配置BFD特性

# 配置RouterA。

[RouterA] bfd

[RouterA-bfd] quit

[RouterA] interface GigabitEthernet 1/0/0

[RouterA-GigabitEthernet1/0/0] bfd

[RouterA-GigabitEthernet1/0/0] quit

[RouterA] bfd atob bind peer-ip 10.1.1.2 interface GigabitEthernet 1/0/0

[RouterA-bfd-session-atob] discriminator local 1

[RouterA-bfd-session-atob] discriminator remote 2

[RouterA-bfd-session-atob] commit

[RouterA-bfd-session-atob] quit

[RouterA] interface GigabitEthernet 1/0/0

[RouterA-GigabitEthernet1/0/0] isis fast-sense

[RouterA-GigabitEthernet1/0/0] quit

# 配置RouterB。

[RouterB] bfd

[RouterB-bfd] quit

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] bfd

[RouterB-GigabitEthernet1/0/0] quit

[RouterB] bfd atob bind peer-ip 10.1.1.1 interface GigabitEthernet 1/0/0

[RouterB-bfd-session-atob] discriminator local 2

[RouterB-bfd-session-atob] discriminator remote 1

[RouterB-bfd-session-atob] commit

[RouterB-bfd-session-atob] quit

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] isis fast-sense

[RouterB-GigabitEthernet1/0/0] quit

步骤 4     关闭hello报文填充

# 配置RouterA。

[RouterA] interface GigabitEthernet 1/0/0

[RouterA-GigabitEthernet1/0/0] isis small-hello

[RouterA-GigabitEthernet1/0/0] quit

# 配置RouterB

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] isis small-hello

[RouterB-GigabitEthernet1/0/0] quit

在邻接关系的建立过程中，IS-IS需要检查链路两端的MTU大小是否一致。缺省情况下，IS-IS协议将Hello报文填充至MTU大小。可以通过该命令简化Hello报文的收发操作，减小对网络带宽的浪费。

步骤 5     配置快速收敛时间参数

# 配置RouterA。

[RouterA] isis

[RouterA-isis-1] timer spf 1 50 100

[RouterA-isis-1] timer lsp-generation 1 1 120

# 配置RouterB。

[RouterB] isis

[RouterB-isis-1] timer spf 1 50 100

[RouterB-isis-1] timer lsp-generation 1 1 120

说明

spf默认值：10s、100ms、5s

lsp-generation默认值：5s、50ms、5s

步骤 6     检查配置结果

# 在RouterB的GE1/0/0端口上执行命令shutdown，模拟链路down掉。

[RouterB] interface GigabitEthernet 1/0/0

[RouterB-GigabitEthernet1/0/0] shutdown

# 在RouterA上查看路由计算时间。

<RouterA> debugging isis spf-summary

<RouterA> terminal debugging

<RouterA> terminal monitor

%Sep 26 12:10:29 2006 Quidway BFD/5/BFD:IO(6) BFD Session(Discr:1) FSM Change To

 Down(Detect)

%Sep 26 12:10:29 2006 Quidway RM/4/RMLOG:ISIS-FastSense: Deleting Neighbour by I

P Address 10.1.1.2 On GigabitEthernet1/0/0

*0.9978760 Quidway ISIS/7/ISIS:

  Prc job completed at Sec = 09919, MSec = 390.

 

*0.9978760 Quidway ISIS/7/ISIS:

  Signal SPF at Sec = 09978, MSec = 760.

 

*0.9978870 Quidway ISIS/7/ISIS:

  Signal SPF at Sec = 09978, MSec = 760.

 

*0.9978870 Quidway ISIS/7/ISIS:

  ISpf starts at Sec = 09978, MSec = 810.ISIS-1-SPF-STATS: RT Calculation: Elaps

ed time: 0 Milliseconds

 

*0.9978870 Quidway ISIS/7/ISIS:

 ISIS-1-SPF-PRC: Received L2 System Change Event for 0000.0000.0002.00, Change =

 2

 

*0.9978870 Quidway ISIS/7/ISIS:

 ISIS-1-SPF-PRC: Received L2 System Change Event for 0000.0000.0002.01, Change =

 2

 

*0.9978870 Quidway ISIS/7/ISIS:

 ISIS-1-DEC-PRC: Igorning pseudo-node system change information from the ISPF mo

dule.

 

*0.9978870 Quidway ISIS/7/ISIS:

 

 

*0.9978870 Quidway ISIS/7/ISIS:

  ISpf ends(and prc starts) at Sec = 09978, MSec = 810.

 

*0.9978870 Quidway ISIS/7/ISIS:

  Prc job starts to run at Sec = 09978, MSec = 810.ISIS-1-SPF-PRC: Processing L2

 LSPs of System :0000.0000.0002, Change Type = 2

当BFD感知链路down掉时，立刻删除邻居，激发路由计算，使网络迅速收敛。

配置文件
RouterA的配置文件
#

 sysname RouterA

#

 bfd

#

isis 1

 is-level level-2

 timer lsp-generation 1 1 120 level-1

 timer lsp-generation 1 1 120 level-2

 network-entity 10.0000.0000.0001.00

 timer spf 1 50 100

#

interface GigabitEthernet1/0/0

 ip address 10.1.1.1 255.255.255.0

 isis enable 1

 isis fast-sense

 isis small-hello

 bfd

#

bfd 1 bind peer-ip 10.1.1.2 interface GigabitEthernet1/0/0

 discriminator local 1

 discriminator remote 2

 commit

#

return

RouterB的配置文件
#

 sysname RouterB

#

 bfd

#

isis 1

 is-level level-2

 timer lsp-generation 1 1 120 level-1

 timer lsp-generation 1 1 120 level-2

 network-entity 10.0000.0000.0002.00

 timer spf 1 50 100

#

interface GigabitEthernet1/0/0

ip address 10.1.1.2 255.255.255.0

 isis enable 1

 isis fast-sense

 isis small-hello

 bfd

#

bfd 1 bind peer-ip 10.1.1.1 interface GigabitEthernet1/0/0

 discriminator local 2

 discriminator remote 1

 commit

#

return