配置LDP跨域扩展示例
组网需求
当网络规模比较大时,通常需要配置多个IGP区域来达到灵活部署和快速收敛的目的。在这种情况下,IGP区域间进行路由通告时,为了避免路由数量多而引起的对资源的过多占用,区域边界路由器(ABR)需要将区域内路由聚合,再通告给相邻的IGP区域。然而,缺省情况下,LDP在建立LSP的时候,会在路由表中查找与收到的标签映射消息中携带的FEC精确匹配的路由,对于聚合路由,LDP只能建立Liberal LSP,无法建立跨越IGP区域的LDP LSP。
如图3-37所示,各设备间运行IS-IS路由协议。存在Area 10和Area 20两个IGP域,LSRD将LSRB和LSRC路由聚合发送到Area 20区域。在部署MPLS业务时,要求建立LSRA到LSRB以及LSRA到LSRC的跨越两个IGP域的LSP。
操作步骤
- 配置各接口的IP地址
# 配置LSRA。LSRB、LSRC和LSRD的配置与LSRA类似,不再赘述。
<Huawei> system-view [Huawei] sysname LSRA [LSRA] interface loopback 0 [LSRA-LoopBack0] ip address 10.1.0.1 32 [LSRA-LoopBack0] quit [LSRA] interface gigabitethernet 1/0/0 [LSRA-GigabitEthernet1/0/0] ip address 10.1.1.1 24 [LSRA-GigabitEthernet1/0/0] quit
- 配置IS-IS协议的基本功能
# 配置LSRA。
[LSRA] isis 1 [LSRA-isis-1] is-level level-2 [LSRA-isis-1] network-entity 20.0010.0100.0001.00 [LSRA-isis-1] quit [LSRA] interface gigabitethernet 1/0/0 [LSRA-GigabitEthernet1/0/0] isis enable 1 [LSRA-GigabitEthernet1/0/0] quit [LSRA] interface loopback 0 [LSRA-LoopBack0] isis enable 1 [LSRA-LoopBack0] quit
# 配置LSRD。
[LSRD] isis 1 [LSRD-isis-1] network-entity 10.0010.0200.0001.00 [LSRD-isis-1] quit [LSRD] interface gigabitethernet 1/0/0 [LSRD-GigabitEthernet1/0/0] isis enable 1 [LSRD-GigabitEthernet1/0/0] isis circuit-level level-2 [LSRD-GigabitEthernet1/0/0] quit [LSRD] interface gigabitethernet 1/0/1 [LSRD-GigabitEthernet1/0/1] isis enable 1 [LSRD-GigabitEthernet1/0/1] isis circuit-level level-1 [LSRD-GigabitEthernet1/0/1] quit [LSRD] interface gigabitethernet 2/0/0 [LSRD-GigabitEthernet2/0/0] isis enable 1 [LSRD-GigabitEthernet2/0/0] isis circuit-level level-1 [LSRD-GigabitEthernet2/0/0] quit [LSRD] interface loopback 0 [LSRD-LoopBack0] isis enable 1 [LSRD-LoopBack0] quit
# 配置LSRB。
[LSRB] isis 1 [LSRB-isis-1] is-level level-1 [LSRB-isis-1] network-entity 10.0010.0300.0001.00 [LSRB-isis-1] quit [LSRB] interface gigabitethernet 1/0/0 [LSRB-GigabitEthernet1/0/0] isis enable 1 [LSRB-GigabitEthernet1/0/0] quit [LSRB] interface loopback 0 [LSRB-LoopBack0] isis enable 1 [LSRB-LoopBack0] quit
# 配置LSRC。
[LSRC] isis 1 [LSRC-isis-1] is-level level-1 [LSRC-isis-1] network-entity 10.0010.0300.0002.00 [LSRC-isis-1] quit [LSRC] interface gigabitethernet 1/0/0 [LSRC-GigabitEthernet1/0/0] isis enable 1 [LSRC-GigabitEthernet1/0/0] quit [LSRC] interface loopback 0 [LSRC-LoopBack0] isis enable 1 [LSRC-LoopBack0] quit
# 在LSRA上执行display ip routing-table命令查看路由信息。
[LSRA] display ip routing-table Route Flags: R - relay, D - download to fib ------------------------------------------------------------------------------ Routing Tables: Public Destinations : 13 Routes : 13 Destination/Mask Proto Pre Cost Flags NextHop Interface 10.1.0.1/32 Direct 0 0 D 127.0.0.1 LoopBack0 10.2.0.1/32 ISIS-L2 15 10 D 10.1.1.2 GigabitEthernet1/0/0 10.3.0.1/32 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 10.3.0.2/32 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 10.1.1.0/24 Direct 0 0 D 10.1.1.1 GigabitEthernet1/0/0 10.1.1.1/32 Direct 0 0 D 127.0.0.1 GigabitEthernet1/0/0 10.1.1.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet1/0/0 10.2.1.0/24 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 10.2.2.0/24 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
- 配置聚合路由的策略
# 在LSRD上执行summary命令将到LSRB和LSRC的主机路由聚合。
[LSRD] isis 1 [LSRD-isis-1] summary 10.3.0.0 255.255.255.0 avoid-feedback
# 在LSRA上执行display ip routing-table命令查看路由信息。
[LSRA] display ip routing-table Route Flags: R - relay, D - download to fib ------------------------------------------------------------------------------ Routing Tables: Public Destinations : 12 Routes : 12 Destination/Mask Proto Pre Cost Flags NextHop Interface 10.1.0.1/32 Direct 0 0 D 127.0.0.1 LoopBack0 10.2.0.1/32 ISIS-L2 15 10 D 10.1.1.2 GigabitEthernet1/0/0 10.3.0.0/24 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 10.1.1.0/24 Direct 0 0 D 10.1.1.1 GigabitEthernet1/0/0 10.1.1.1/32 Direct 0 0 D 127.0.0.1 GigabitEthernet1/0/0 10.1.1.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet1/0/0 10.2.1.0/24 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 10.2.2.0/24 ISIS-L2 15 20 D 10.1.1.2 GigabitEthernet1/0/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
从显示信息可以看到,到LSRB和LSRC的主机路由已经聚合。
- 配置各节点全局和接口的MPLS和MPLS LDP能力,使网络能够转发MPLS流量,并查看LSP建立情况
# 配置LSRA。
[LSRA] mpls lsr-id 10.1.0.1 [LSRA] mpls [LSRA-mpls] quit [LSRA] mpls ldp [LSRA-mpls-ldp] quit [LSRA] interface gigabitethernet 1/0/0 [LSRA-GigabitEthernet1/0/0] mpls [LSRA-GigabitEthernet1/0/0] mpls ldp [LSRA-GigabitEthernet1/0/0] quit
# 配置LSRD。
[LSRD] mpls lsr-id 10.2.0.1 [LSRD] mpls [LSRD-mpls] quit [LSRD] mpls ldp [LSRD-mpls-ldp] quit [LSRD] interface gigabitethernet 1/0/0 [LSRD-GigabitEthernet1/0/0] mpls [LSRD-GigabitEthernet1/0/0] mpls ldp [LSRD-GigabitEthernet1/0/0] quit [LSRD] interface gigabitethernet 1/0/1 [LSRD-GigabitEthernet1/0/1] mpls [LSRD-GigabitEthernet1/0/1] mpls ldp [LSRD-GigabitEthernet1/0/1] quit [LSRD] interface gigabitethernet 2/0/0 [LSRD-GigabitEthernet2/0/0] mpls [LSRD-GigabitEthernet2/0/0] mpls ldp [LSRD-GigabitEthernet2/0/0] quit
# 配置LSRB。
[LSRB] mpls lsr-id 10.3.0.1 [LSRB] mpls [LSRB-mpls] quit [LSRB] mpls ldp [LSRB-mpls-ldp] quit [LSRB] interface gigabitethernet 1/0/0 [LSRB-GigabitEthernet1/0/0] mpls [LSRB-GigabitEthernet1/0/0] mpls ldp [LSRB-GigabitEthernet1/0/0] quit
# 配置LSRC。
[LSRC] mpls lsr-id 10.3.0.2 [LSRC] mpls [LSRC-mpls] quit [LSRC] mpls ldp [LSRC-mpls-ldp] quit [LSRC] interface gigabitethernet 1/0/0 [LSRC-GigabitEthernet1/0/0] mpls [LSRC-GigabitEthernet1/0/0] mpls ldp [LSRC-GigabitEthernet1/0/0] quit
# 配置完成后,在LSRA上执行display mpls lsp命令,查看已经建立的LSP。
[LSRA] display mpls lsp ------------------------------------------------------------------------------- LSP Information: LDP LSP ------------------------------------------------------------------------------- FEC In/Out Label In/Out IF Vrf Name 10.2.0.1/32 NULL/3 -/GE1/0/0 10.2.0.1/32 1024/3 -/GE1/0/0 10.1.0.1/32 3/NULL -/-
从显示信息可以看到,缺省情况下,LDP没有建立从LSRA到LSRB和LSRC的跨域LSP。
- 配置LDP跨域扩展
# 在LSRA上执行longest-match命令,使能LDP按照最长匹配方式查找路由建立LSP。
[LSRA] mpls ldp [LSRA-mpls-ldp] longest-match [LSRA-mpls-ldp] quit
- 验证配置结果
# 上述配置完成后,在LSRA上执行display mpls lsp命令,查看已经建立的LSP。
[LSRA] display mpls lsp ------------------------------------------------------------------------------- LSP Information: LDP LSP ------------------------------------------------------------------------------- FEC In/Out Label In/Out IF Vrf Name 10.2.0.1/32 NULL/3 -/GE1/0/0 10.2.0.1/32 1024/3 -/GE1/0/0 10.3.0.1/32 NULL/1025 -/GE1/0/0 10.3.0.1/32 1025/1025 -/GE1/0/0 10.3.0.2/32 NULL/1026 -/GE1/0/0 10.3.0.2/32 1026/1026 -/GE1/0/0 10.1.0.1/32 3/NULL -/-
从显示信息可以看到,LDP建立了从LSRA到LSRB和LSRC的跨越两个IGP域的LSP。
配置文件
LSRA的配置文件
# sysname LSRA # mpls lsr-id 10.1.0.1 mpls # mpls ldp longest-match # isis 1 is-level level-2 network-entity 20.0010.0100.0001.00 # interface GigabitEthernet1/0/0 ip address 10.1.1.1 255.255.255.0 isis enable 1 mpls mpls ldp # interface LoopBack0 ip address 10.1.0.1 255.255.255.255 isis enable 1 # return
LSRD的配置文件
# sysname LSRD # mpls lsr-id 10.2.0.1 mpls # mpls ldp # isis 1 network-entity 10.0010.0200.0001.00 summary 10.3.0.0 255.255.255.0 avoid-feedback # interface GigabitEthernet1/0/0 ip address 10.1.1.2 255.255.255.0 isis enable 1 isis circuit-level level-2 mpls mpls ldp # interface GigabitEthernet1/0/1 ip address 10.2.2.1 255.255.255.0 isis enable 1 isis circuit-level level-1 mpls mpls ldp # interface GigabitEthernet2/0/0 ip address 10.2.1.1 255.255.255.0 isis enable 1 isis circuit-level level-1 mpls mpls ldp # interface LoopBack0 ip address 10.2.0.1 255.255.255.255 isis enable 1 # return
LSRB的配置文件
# sysname LSRB # mpls lsr-id 10.3.0.1 mpls # mpls ldp # isis 1 is-level level-1 network-entity 10.0010.0300.0001.00 # interface GigabitEthernet1/0/0 ip address 10.2.1.2 255.255.255.0 isis enable 1 mpls mpls ldp # interface LoopBack0 ip address 10.3.0.1 255.255.255.255 isis enable 1 # return
LSRC的配置文件
# sysname LSRC # mpls lsr-id 10.3.0.2 mpls # mpls ldp # isis 1 is-level level-1 network-entity 10.0010.0300.0002.00 # interface GigabitEthernet1/0/0 ip address 10.2.2.2 255.255.255.0 isis enable 1 mpls mpls ldp # interface LoopBack0 ip address 10.3.0.2 255.255.255.255 isis enable 1 # return