使用quagga配置BGP

BGP相对OSPF来说在骨干网络上使用的比较多，是目前域间路由协议的事实标准。通常在服务器上直接使用BGP的场景不多（内部网络大家都倾向使用OSPF这类IGP）。
其实BGP的配置也很简单，从以下的拓扑来看4个机器的BGP配置
https://blog.gnuers.org/?attachment_id=1351

各路由配置文件

R1 配置

!  
log file /var/log/quagga/zebra.log  
log file /var/log/quagga/bgpd.log  
!  
password bgp  
!  
interface eth0  
ipv6 nd suppress-ra  
link-detect  
!  
interface eth1  
ipv6 nd suppress-ra  
no link-detect  
!  
interface lo  
no link-detect  
!  
interface tunl0  
ipv6 nd suppress-ra  
no link-detect  
!  
router bgp 65000  
bgp router-id 10.1.0.5  
redistribute connected metric 121  
neighbor 10.1.0.4 remote-as 65000  
neighbor 10.1.0.4 password DOCKER  
neighbor 10.1.0.4 next-hop-self  
distance bgp 250 200 150  
exit  
!  
access-list all permit any  
!  
ip forwarding  
ipv6 forwarding  
!  
line vty  
!  
end

R2 配置

log file /var/log/quagga/zebra.log  
log file /var/log/quagga/bgpd.log  
!  
password bgp  
!  
interface eth0  
ipv6 nd suppress-ra  
link-detect  
!  
interface eth1  
ipv6 nd suppress-ra  
no link-detect  
!  
interface lo  
no link-detect  
!  
interface tunl0  
ipv6 nd suppress-ra  
no link-detect  
!  
router bgp 65000  
bgp router-id 10.1.0.3  
redistribute connected metric 121  
neighbor 10.1.0.4 remote-as 65000  
neighbor 10.1.0.4 password DOCKER  
neighbor 10.1.0.4 next-hop-self  
distance bgp 250 200 150  
exit  
!  
access-list all permit any  
!  
ip forwarding  
ipv6 forwarding  
!  
line vty  
!  
end

R3 配置

log file /var/log/quagga/zebra.log  
log file /var/log/quagga/bgpd.log  
!  
password bgp  
!  
interface eth0  
ipv6 nd suppress-ra  
link-detect  
!  
interface eth1  
ipv6 nd suppress-ra  
no link-detect  
!  
interface lo  
no link-detect  
!  
router bgp 65000  
bgp router-id 10.1.0.4  
redistribute connected metric 121  
neighbor IBGP peer-group  
neighbor IBGP remote-as 65000  
neighbor IBGP password DOCKER  
neighbor 10.1.0.2 remote-as 65001  
neighbor 10.1.0.2 password DOCKER  
neighbor 10.1.0.2 ebgp-multihop 255  
neighbor 10.1.0.3 peer-group IBGP  
neighbor 10.1.0.5 peer-group IBGP  
maximum-paths ibgp 32  
distance bgp 250 200 150  
exit  
!  
access-list all permit any  
!  
ip forwarding  
ipv6 forwarding  
!  
line vty  
!  
end

R4配置

log file /var/log/quagga/zebra.log  
log file /var/log/quagga/bgpd.log  
!  
password bgp  
!  
interface eth0  
ipv6 nd suppress-ra  
link-detect  
!  
interface eth1  
ipv6 nd suppress-ra  
no link-detect  
!  
interface lo  
no link-detect  
!  
interface tunl0  
ipv6 nd suppress-ra  
no link-detect  
!  
router bgp 65001  
bgp router-id 10.1.0.2  
redistribute connected metric 121  
neighbor 10.1.0.4 remote-as 65000  
neighbor 10.1.0.4 password DOCKER  
neighbor 10.1.0.4 next-hop-self  
distance bgp 250 200 150  
exit  
!  
access-list all permit any  
!  
ip forwarding  
ipv6 forwarding  
!  
line vty  
!  
end

BGP邻居状态

R3与其他节点都是邻居，因此以R3的为例

c78df8a1d9d5# show ip bgp neighbors  
BGP neighbor is 10.1.0.2, remote AS 65001, local AS 65000, external link  
BGP version 4, remote router ID 10.1.0.2  
BGP state = Established, up for 01:33:01  
Last read 00:00:01, hold time is 180, keepalive interval is 60 seconds  
Neighbor capabilities:  
4 Byte AS: advertised and received  
Route refresh: advertised and received(old & new)  
Address family IPv4 Unicast: advertised and received  
Graceful Restart Capabilty: advertised and received  
Remote Restart timer is 120 seconds  
Address families by peer:  
none  
Graceful restart informations:  
End-of-RIB send: IPv4 Unicast  
End-of-RIB received: IPv4 Unicast  
Message statistics:  
Inq depth is 0  
Outq depth is 0  
Sent       Rcvd  
Opens:                  1          1  
Notifications:          0          0  
Updates:                5          2  
Keepalives:            95         94  
Route Refresh:          0          0  
Capability:             0          0  
Total:                101         97  
Minimum time between advertisement runs is 30 seconds  
  
For address family: IPv4 Unicast  
Community attribute sent to this neighbor(both)  
3 accepted prefixes  
  
Connections established 1; dropped 0  
Last reset never  
External BGP neighbor may be up to 255 hops away.  
Local host: 10.1.0.4, Local port: 36686  
Foreign host: 10.1.0.2, Foreign port: 179  
Nexthop: 10.1.0.4  
Nexthop global: ::  
Nexthop local: ::  
BGP connection: non shared network  
Read thread: on  Write thread: off  
  
BGP neighbor is 10.1.0.3, remote AS 65000, local AS 65000, internal link  
Member of peer-group IBGP for session parameters  
BGP version 4, remote router ID 10.1.0.3  
BGP state = Established, up for 01:32:57  
Last read 00:00:57, hold time is 180, keepalive interval is 60 seconds  
Neighbor capabilities:  
4 Byte AS: advertised and received  
Route refresh: advertised and received(old & new)  
Address family IPv4 Unicast: advertised and received  
Graceful Restart Capabilty: advertised and received  
Remote Restart timer is 120 seconds  
Address families by peer:  
none  
Graceful restart informations:  
End-of-RIB send: IPv4 Unicast  
End-of-RIB received: IPv4 Unicast  
Message statistics:  
Inq depth is 0  
Outq depth is 0  
Sent       Rcvd  
Opens:                  2          0  
Notifications:          0          0  
Updates:                3          2  
Keepalives:            94         93  
Route Refresh:          0          0  
Capability:             0          0  
Total:                 99         95  
Minimum time between advertisement runs is 5 seconds  
  
For address family: IPv4 Unicast  
IBGP peer-group member  
Community attribute sent to this neighbor(both)  
4 accepted prefixes  
  
Connections established 1; dropped 0  
Last reset never  
Local host: 10.1.0.4, Local port: 179  
Foreign host: 10.1.0.3, Foreign port: 43991  
Nexthop: 10.1.0.4  
Nexthop global: ::  
Nexthop local: ::  
BGP connection: non shared network  
Read thread: on  Write thread: off  
  
BGP neighbor is 10.1.0.5, remote AS 65000, local AS 65000, internal link  
Member of peer-group IBGP for session parameters  
BGP version 4, remote router ID 10.1.0.5  
BGP state = Established, up for 01:32:56  
Last read 00:00:56, hold time is 180, keepalive interval is 60 seconds  
Neighbor capabilities:  
4 Byte AS: advertised and received  
Route refresh: advertised and received(old & new)  
Address family IPv4 Unicast: advertised and received  
Graceful Restart Capabilty: advertised and received  
Remote Restart timer is 120 seconds  
Address families by peer:  
none  
Graceful restart informations:  
End-of-RIB send: IPv4 Unicast  
End-of-RIB received: IPv4 Unicast  
Message statistics:  
Inq depth is 0  
Outq depth is 0  
Sent       Rcvd  
Opens:                  2          0  
Notifications:          0          0  
Updates:                3          2  
Keepalives:            94         93  
Route Refresh:          0          0  
Capability:             0          0  
Total:                 99         95  
Minimum time between advertisement runs is 5 seconds  
  
For address family: IPv4 Unicast  
IBGP peer-group member  
Community attribute sent to this neighbor(both)  
4 accepted prefixes  
  
Connections established 1; dropped 0  
Last reset never  
Local host: 10.1.0.4, Local port: 179  
Foreign host: 10.1.0.5, Foreign port: 42140  
Nexthop: 10.1.0.4  
Nexthop global: ::  
Nexthop local: ::  
BGP connection: non shared network  
Read thread: on  Write thread: off

各节点上的路由表

  • R3上ECMP路由
default via 172.19.0.1 dev eth1  
10.1.0.0/16 dev eth0  proto kernel  scope link  src 10.1.0.4  
100.100.100.1 via 10.1.0.5 dev eth0  proto zebra  metric 20  
100.100.100.2 via 10.1.0.3 dev eth0  proto zebra  metric 20  
100.100.100.4 via 10.1.0.2 dev eth0  proto zebra  metric 20  
100.100.100.100  proto zebra  metric 20  
nexthop via 10.1.0.5  dev eth0 weight 1  
nexthop via 10.1.0.3  dev eth0 weight 1  
172.18.0.0/16 via 10.1.0.5 dev eth0  proto zebra  metric 20  
172.19.0.0/16 dev eth1  proto kernel  scope link  src 172.19.0.2

其他说明

  • 本测试中用了peer group，主要是IBGP内多个邻居测试比较简单一些。

  • quagga内默认IBGP的路径最大是1，通过maximum-paths ibgp 32改了一下。

  • 本案例中R1和R2是不通的，因为IBGP内未做特殊设置(BGP反射或者BGP联盟)是不会接受其他IBGP邻居传递的路由。

  • 要想能从R4访问R1/R2宣告的100.100.100.100/32需要注意linux的kernel版本。。3.10的版本是按每个包单独转发，是建立不了TCP连接的。我测试时升级到了4.4.## 参考文档

  • https://lwn.net/Articles/656111/