配置OSPF与BGP联动特性示例
介绍OSPF与BGP联动功能的配置过程,使得当路由器重启后,减小对网络中BGP流量的影响。
组网需求
如图5-17所示,所有路由器均为BGP设备,DeviceD和DeviceE之间建立EBGP连接。在AS10内的设备之间建立IBGP连接,并且使用OSPF作为IGP协议。
要求在DeviceB上使能OSPF与BGP联动功能,使得当DeviceB重启后,从DeviceA到AS20的流量不发生中断。
配置思路
采用如下的思路配置OSPF与BGP联动功能。
在DeviceA、DeviceB、DeviceC和DeviceD(除去10.2.1.1/30)上使能OSPF协议,指定相同区域内的网段。
在DeviceA、DeviceB、DeviceC和DeviceD(除去10.2.1.1/30)之间建立IBGP连接。
在DeviceC上配置OSPF协议的开销值。
在DeviceD和DeviceE之间配置EBGP连接。
在DeviceD上配置BGP引入直连路由和OSPF进程。
在DeviceE上配置BGP。
数据准备
为完成此配置例,需准备如下的数据:
DeviceA的Router ID 1.1.1.1,所在的AS号10,运行的OSPF进程号1,在区域0的网段是10.1.1.0/30,10.1.2.0/30。
DeviceB的Router ID 2.2.2.2,所在的AS号10,运行的OSPF进程号1,在区域0的网段是10.1.1.0/30,10.1.3.0/30。
DeviceC的Router ID 3.3.3.3,所在的AS号10,运行的OSPF进程号1,在区域0的网段是10.1.2.0/30,10.1.4.0/30。
DeviceD的Router ID 4.4.4.4,所在的AS号10,运行的OSPF进程号1,在区域0的网段是10.1.3.0/30,10.1.4.0/30。
DeviceE的Router ID 5.5.5.5,所在的AS号20。
操作步骤
- 配置各接口的IP地址(略)
- 配置OSPF基本功能(请参见配置OSPF基本功能示例)
- 配置IBGP全连接
# 配置DeviceA。
<DeviceA> system-view
[~DeviceA] interface loopback 0
[*DeviceA-LoopBack0] ip address 1.1.1.1 32
[*DeviceA-LoopBack0] quit
[*DeviceA] bgp 10
[*DeviceA-bgp] router-id 1.1.1.1
[*DeviceA-bgp] peer 2.2.2.2 as-number 10 [*DeviceA-bgp] peer 2.2.2.2 connect-interface LoopBack 0 [*DeviceA-bgp] peer 3.3.3.3 as-number 10 [*DeviceA-bgp] peer 3.3.3.3 connect-interface LoopBack 0 [*DeviceA-bgp] peer 4.4.4.4 as-number 10 [*DeviceA-bgp] peer 4.4.4.4 connect-interface LoopBack 0
[*DeviceA-bgp] quit
[*DeviceA] commit
# 配置DeviceB。
<DeviceB> system-view
[~DeviceB] interface loopback 0
[*DeviceB-LoopBack0] ip address 2.2.2.2 32
[*DeviceB-LoopBack0] quit
[*DeviceB] bgp 10
[*DeviceB-bgp] router-id 2.2.2.2
[*DeviceB-bgp] peer 1.1.1.1 as-number 10 [*DeviceB-bgp] peer 1.1.1.1 connect-interface LoopBack 0 [*DeviceB-bgp] peer 3.3.3.3 as-number 10 [*DeviceB-bgp] peer 3.3.3.3 connect-interface LoopBack 0 [*DeviceB-bgp] peer 4.4.4.4 as-number 10 [*DeviceB-bgp] peer 4.4.4.4 connect-interface LoopBack 0
[*DeviceB-bgp] quit
[*DeviceB] commit
# 配置DeviceC。
<DeviceC> system-view
[~DeviceC] interface loopback 0
[*DeviceC-LoopBack0] ip address 3.3.3.3 32
[*DeviceC-LoopBack0] quit
[*DeviceC] bgp 10
[*DeviceC-bgp] router-id 3.3.3.3
[*DeviceC-bgp] peer 1.1.1.1 as-number 10 [*DeviceC-bgp] peer 1.1.1.1 connect-interface LoopBack 0 [*DeviceC-bgp] peer 2.2.2.2 as-number 10 [*DeviceC-bgp] peer 2.2.2.2 connect-interface LoopBack 0 [*DeviceC-bgp] peer 4.4.4.4 as-number 10 [*DeviceC-bgp] peer 4.4.4.4 connect-interface LoopBack 0
[*DeviceC-bgp] quit
[*DeviceC] commit
# 配置DeviceD。
<DeviceD> system-view
[~DeviceD] interface loopback 0
[*DeviceD-LoopBack0] ip address 4.4.4.4 32
[*DeviceD-LoopBack0] quit
[*DeviceD] bgp 10
[*DeviceD-bgp] router-id 4.4.4.4
[*DeviceD-bgp] peer 1.1.1.1 as-number 10 [*DeviceD-bgp] peer 1.1.1.1 connect-interface LoopBack 0 [*DeviceD-bgp] peer 2.2.2.2 as-number 10 [*DeviceD-bgp] peer 2.2.2.2 connect-interface LoopBack 0 [*DeviceD-bgp] peer 3.3.3.3 as-number 10 [*DeviceD-bgp] peer 3.3.3.3 connect-interface LoopBack 0
[*DeviceD-bgp] quit
[*DeviceD] commit
- 配置EBGP连接
# 配置DeviceD。
[*DeviceD] bgp 10
[*DeviceD-bgp] peer 10.2.1.2 as-number 20
[*DeviceD-bgp] import-route direct
[*DeviceD-bgp] import-route ospf 1
[*DeviceD-bgp] quit
[*DeviceD] commit
# 配置DeviceE。
[*DeviceE] bgp 20
[*DeviceE-bgp] peer 10.2.1.1 as-number 10
[*DeviceE-bgp] ipv4-family unicast
[*DeviceE-bgp-af-ipv4] network 10.3.1.0 30
[*DeviceE-bgp-af-ipv4] quit
[*DeviceE-bgp] commit
- 配置DeviceC上OSPF协议的开销值
[~DeviceC] interface gigabitethernet 0/1/0
[*DeviceC-GigabitEthernet0/1/0] ospf cost 2
[*DeviceC-GigabitEthernet0/1/0] quit
[~DeviceC] interface gigabitethernet 0/2/0
[*DeviceC-GigabitEthernet0/2/0] ospf cost 2
[*DeviceC-GigabitEthernet0/2/0] commit
[~DeviceC-GigabitEthernet0/2/0] quit
通过配置DeviceC上OSPF协议的开销值为2,使得DeviceA只选择DeviceB作为到10.2.1.0网段的中间路由器,DeviceC成为DeviceB的备份路由器。
# 查看DeviceA的路由表。从路由表中可以看出,通过BGP协议可以学习到目标网段10.1.3.0的路由,出接口是GigabitEthernet0/1/0。
[~DeviceA] display ip routing-table
Route Flags: R - relied, D - download to fib ------------------------------------------------------------------------------ Routing Tables: _public_ Destinations : 20 Routes : 20 Destination/Mask Proto Pre Cost Flags NextHop Interface 1.1.1.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 1.1.1.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 2.2.2.2/32 OSPF 10 3 D 10.1.1.2 GigabitEthernet0/1/0 4.4.4.0/24 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 4.4.4.4/32 OSPF 10 3 D 10.1.1.2 GigabitEthernet0/1/0 5.5.5.0/24 BGP 255 0 RD 10.2.1.2 GigabitEthernet0/1/0 10.1.1.0/30 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.3/32 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.1.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.1.255/32 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.2/32 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.255/32 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.2.0/30 Direct 0 0 D 10.1.2.1 GigabitEthernet0/2/0 10.1.2.3/32 Direct 0 0 D 10.1.2.1 GigabitEthernet0/2/0 10.1.2.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.2/32 Direct 0 0 D 10.1.2.2 GigabitEthernet0/2/0 10.1.2.255/32 Direct 0 0 D 10.1.2.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.0/30 OSPF 10 2 D 10.1.1.2 GigabitEthernet0/1/0 10.1.3.1/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 10.1.4.0/30 OSPF 10 3 D 10.1.1.2 GigabitEthernet0/1/0 OSPF 10 3 D 10.1.2.2 GigabitEthernet0/2/0 10.1.4.1/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 10.2.1.0/30 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 10.2.1.2/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 10.3.1.0/30 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/1/0 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
# 查看DeviceB的路由表。
[~DeviceB] display ip routing-table
Route Flags: R - relied, D - download to fib ------------------------------------------------------------------------------ Routing Tables: _public_ Destinations : 19 Routes : 19 Destination/Mask Proto Pre Cost Flags NextHop Interface 2.2.2.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 2.2.2.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 1.1.1.1/32 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/1/0 4.4.4.0/24 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 4.4.4.4/32 OSPF 10 2 D 10.1.3.2 GigabitEthernet0/2/0 5.5.5.0/24 BGP 255 0 RD 10.2.1.2 GigabitEthernet0/2/0 10.1.1.0/30 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.3/32 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.1/32 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.255/32 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.1.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.0/30 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/1/0 10.1.3.0/30 Direct 0 0 D 10.1.3.1 GigabitEthernet0/2/0 10.1.3.3/32 Direct 0 0 D 10.1.3.1 GigabitEthernet0/2/0 10.1.3.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.2/32 Direct 0 0 D 10.1.3.2 GigabitEthernet0/2/0 10.1.3.255/32 Direct 0 0 D 10.1.3.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.4.0/30 OSPF 10 2 D 10.1.3.2 GigabitEthernet0/2/0 10.1.4.1/32 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.2.1.0/30 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.2.1.2/32 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.3.1.0/30 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
从路由表中可以看出,DeviceB通过BGP协议可以学习到目标网段10.3.1.0的路由,出接口是GigabitEthernet0/2/0。通过OSPF协议可以学习到目标网段10.1.2.0和10.1.4.0的路由,路由开销都是2。
- 在DeviceB上使能OSPF与BGP联动功能
[*DeviceB] ospf 1
[*DeviceB-ospf-1] stub-router on-startup
[*DeviceB-ospf-1] commit
- 查看配置结果
# 重启路由器DeviceB
在一般情况下,请勿使用该命令,因为它将导致网络工作在短时间内瘫痪,另外在重启路由器时,要确保路由器配置文件是否已经保存了。
[*DeviceB] reboot
System will reboot! Continue?[Y/N] y
# 查看DeviceA的路由表。从路由表中可以看出,通过BGP协议可以学习到目标网段10.3.1.0的路由,出接口变为GigabitEthernet0/2/0。
[~DeviceA] display ip routing-table
Route Flags: R - relied, D - download to fib ------------------------------------------------------------------------------ Routing Tables: _public_ Destinations : 20 Routes : 20 Destination/Mask Proto Pre Cost Flags NextHop Interface 1.1.1.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 2.2.2.2/32 OSPF 10 4 D 10.1.2.2 GigabitEthernet0/2/0 4.4.4.0/24 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0 4.4.4.4/32 OSPF 10 4 D 10.1.2.2 GigabitEthernet0/2/0 5.5.5.0/24 BGP 255 0 RD 10.2.1.2 GigabitEthernet0/2/0 10.1.1.0/30 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.1.2/32 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.2.0/30 Direct 0 0 D 10.1.2.1 GigabitEthernet0/2/0 10.1.2.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.2/32 Direct 0 0 D 10.1.2.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.0/30 OSPF 10 2 D 10.1.1.2 GigabitEthernet0/1/0 10.1.3.1/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0 10.1.4.0/30 OSPF 10 3 D 10.1.2.2 GigabitEthernet0/2/0 10.1.4.1/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0 10.2.1.0/30 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0 10.2.1.2/32 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0 10.3.1.0/30 BGP 255 0 RD 4.4.4.4 GigabitEthernet0/2/0
# 查看DeviceB的路由表。从路由表中可以看出,由于IGP收敛速度比BGP快,所以路由表中暂时只有OSPF路由,并且开销值都已变为较大的数(≥65535)。
[~DeviceB] display ip routing-table
Route Flags: R - relied, D - download to fib ------------------------------------------------------------------------------ Routing Tables: _public_ Destinations : 15 Routes : 15 Destination/Mask Proto Pre Cost Flags NextHop Interface 1.1.1.1/32 OSPF 10 65536 D 10.1.1.1 GigabitEthernet0/1/0 2.2.2.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 4.4.4.4/32 OSPF 10 65536 D 10.1.3.2 GigabitEthernet0/2/0 10.1.1.0/30 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.1/32 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.0/30 OSPF 10 65536 D 10.1.1.1 GigabitEthernet0/1/0 10.1.3.0/30 Direct 0 0 D 10.1.3.1 GigabitEthernet0/2/0 10.1.3.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.2/32 Direct 0 0 D 10.1.3.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.4.0/30 OSPF 10 65536 D 10.1.3.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
# 再次查看DeviceB的路由表。
[~DeviceB] display ip routing-table
Route Flags: R - relied, D - download to fib ------------------------------------------------------------------------------ Routing Tables: _public_ Destinations : 19 Routes : 19 Destination/Mask Proto Pre Cost Flags NextHop Interface 2.2.2.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 1.1.1.1/32 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/1/0 4.4.4.0/24 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 4.4.4.4/32 OSPF 10 2 D 10.1.3.2 GigabitEthernet0/2/0 5.5.5.0/24 BGP 255 0 RD 10.2.1.2 GigabitEthernet0/2/0 10.1.1.0/30 Direct 0 0 D 10.1.1.2 GigabitEthernet0/1/0 10.1.1.1/32 Direct 0 0 D 10.1.1.1 GigabitEthernet0/1/0 10.1.1.2/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.2.0/30 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/1/0 10.1.3.0/30 Direct 0 0 D 10.1.3.1 GigabitEthernet0/2/0 10.1.3.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.3.2/32 Direct 0 0 D 10.1.3.2 GigabitEthernet0/2/0 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0 127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0 10.1.4.0/30 OSPF 10 2 D 10.1.3.2 GigabitEthernet0/2/0 10.1.4.1/32 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.2.1.0/30 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.2.1.2/32 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0 10.3.1.0/30 BGP 255 0 RD 10.1.3.2 GigabitEthernet0/2/0
从路由表中可以看出,当DeviceB上的BGP完全收敛后,路由信息又恢复到重启前的内容。
配置文件
DeviceA的配置文件
# sysname DeviceA # router id 1.1.1.1 # interface GigabitEthernet0/1/0 undo shutdown ip address 10.1.1.1 255.255.255.252 # interface GigabitEthernet0/2/0 undo shutdown ip address 10.1.2.1 255.255.255.252 # interface LoopBack0 ip address 1.1.1.1 255.255.255.255 # bgp 10 router-id 1.1.1.1 peer 2.2.2.2 as-number 10 peer 2.2.2.2 connect-interface LoopBack 0 peer 3.3.3.3 as-number 10 peer 3.3.3.3 connect-interface LoopBack 0 peer 4.4.4.4 as-number 10 peer 4.4.4.4 connect-interface LoopBack 0 # ospf 1 area 0.0.0.0 network 1.1.1.1 0.0.0.0 network 10.1.1.0 0.0.0.3 network 10.1.2.0 0.0.0.3 # return
DeviceB的配置文件
# sysname DeviceB # router id 2.2.2.2 # interface GigabitEthernet0/1/0 undo shutdown ip address 10.1.1.2 255.255.255.252 # interface GigabitEthernet0/2/0 undo shutdown ip address 10.1.3.1 255.255.255.252 # interface LoopBack0 ip address 2.2.2.2 255.255.255.255 # bgp 10 router-id 2.2.2.2 peer 1.1.1.1 as-number 10 peer 1.1.1.1 connect-interface LoopBack 0 peer 3.3.3.3 as-number 10 peer 3.3.3.3 connect-interface LoopBack 0 peer 4.4.4.4 as-number 10 peer 4.4.4.4 connect-interface LoopBack 0 # ospf 1 stub-router on-startup area 0.0.0.0 network 10.1.1.0 0.0.0.3 network 10.1.3.0 0.0.0.3 network 2.2.2.2 0.0.0.0 # return
DeviceC的配置文件
# sysname DeviceC # router id 3.3.3.3 # interface GigabitEthernet0/1/0 undo shutdown ip address 10.1.4.1 255.255.255.252 ospf cost 2 # interface GigabitEthernet0/2/0 undo shutdown ip address 10.1.2.2 255.255.255.252 ospf cost 2 # interface LoopBack0 ip address 3.3.3.3 255.255.255.255 # bgp 10 router-id 3.3.3.3 peer 1.1.1.1 as-number 10 peer 1.1.1.1 connect-interface LoopBack 0 peer 2.2.2.2 as-number 10 peer 2.2.2.2 connect-interface LoopBack 0 peer 4.4.4.4 as-number 10 peer 4.4.4.4 connect-interface LoopBack 0 # ospf 1 area 0.0.0.0 network 10.1.2.0 0.0.0.3 network 10.1.4.0 0.0.0.3 network 3.3.3.3 0.0.0.0 # return
DeviceD的配置文件
# sysname DeviceD # router id 4.4.4.4 # interface GigabitEthernet0/1/0 undo shutdown ip address 10.1.4.2 255.255.255.252 # interface GigabitEthernet0/2/0 undo shutdown ip address 10.1.3.2 255.255.255.252 # interface GigabitEthernet0/3/0 undo shutdown ip address 10.2.1.1 255.255.255.252 # interface LoopBack0 ip address 4.4.4.4 255.255.255.255 # bgp 10 router-id 4.4.4.4 peer 10.2.1.2 as-number 20 peer 1.1.1.1 as-number 10 peer 1.1.1.1 connect-interface LoopBack 0 peer 2.2.2.2 as-number 10 peer 2.2.2.2 connect-interface LoopBack 0 peer 3.3.3.3 as-number 10 peer 3.3.3.3 connect-interface LoopBack 0 # ipv4-family unicast undo synchronization import-route direct import-route ospf 1 peer 10.2.1.2 enable # ospf 1 area 0.0.0.0 network 4.4.4.4 0.0.0.0 network 10.1.3.0 0.0.0.3 network 10.1.4.0 0.0.0.3 # return
DeviceE的配置文件
# sysname DeviceE # router id 5.5.5.5 # interface GigabitEthernet0/1/0 undo shutdown ip address 10.2.1.2 255.255.255.252 # interface GigabitEthernet0/2/0 undo shutdown ip address 10.3.1.1 255.255.255.252 # interface LoopBack0 ip address 5.5.5.5 255.255.255.255 # bgp 20 router-id 5.5.5.5 peer 10.2.1.1 as-number 10 # ipv4-family unicast undo synchronization network 10.3.1.0 255.255.255.252 peer 10.2.1.1 enable # return