路由要优的条件：
1.下一跳可达
2.同步，即从IBGP收到的路由条目，也要求从IGP协议学到
BGP特性:
1.当用了peer-group的方式去建立邻居关系后，就不能针对其中的某个邻居去做一个出方向的策略，只能针对这个组去做相同的策略。
2.BGP打开自动汇总对宣告的影响是，此时可以去宣告一个主类路由了。
3.重分布的时候，自动汇总是生效的。
IBGP邻居水平分割：
从一个IBGP邻居学到的路由不会传给另一个IBGP邻居。从而导致需要运行一个全互联的BGP邻居关系。
1.建立基本的BGP邻居关系
2.路由信息的通告
3.理解同步及解决路由黑洞
4.用peer-group的方法建立邻居关系
5.BGP的自动汇总
6.BGP手动汇总(地址汇聚)
7.产生默认路由
enable
conf t
no ip do lo
enable pass cisco
line con 0
logg sync
exec-t 0 0
line vty 0 4
pass cisco
logg sync
exit
host
1.建立基本的BGP邻居关系
----------------------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 22.1.1.0 0.0.0.255
exit
R1:
ping 22.1.1.1 source 11.1.1.1
R1:
router bgp 100
no synchronization
no auto-summary
bgp router-id 11.1.1.1
neighbor 22.1.1.1 remote-as 100
neighbor 22.1.1.1 update-source l0
exit
R2:
router bgp 100
bgp router-id 22.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
neighbor 23.1.1.3 remote-as 200
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
router bgp 200
bgp router-id 33.1.1.1
neighbor 23.1.1.2 remote-as 100
exit
R2:
show ip bgp summary
2.路由信息的通告
---------------------------------------------------------------------------
R3:
int l0
ip add 33.1.1.1 255.255.255.0
exit
router bgp 200
network 33.1.1.0 mask 255.255.255.0
exit
R1:
router bgp 100
redistribute eigrp 1
exit
R1/R2:
show ip bgp
R2:
router bgp 100
neighbor 11.1.1.1 next-hop-self
exit
3.理解同步及解决路由黑洞
-------------------------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 23.1.1.0 0.0.0.255
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
int l0
ip add 33.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 23.1.1.0 0.0.0.255
network 33.1.1.0 0.0.0.255
exit
R1:
router bgp 100
bgp router-id 11.1.1.1
neighbor 33.1.1.1 remote-as 100
neighbor 33.1.1.1 update-source l0
exit
R3:
router bgp 100
bgp router-id 33.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
exit
R1:
int l1
ip add 100.1.1.1 255.255.255.0
exit
router bgp 100
network 100.1.1.0 mask 255.255.255.0
exit
R3:
show ip bgp
ping 100.1.1.1
R2:
show ip route
R3:
router bgp 100
synchronization
exit
clear ip bgp *
show ip bgp
R2:
int l0
ip add 22.1.1.1 255.255.255.0
exit
router eigrp 1
network 22.1.1.0 0.0.0.255
exit
router bgp 100
bgp router-id 22.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
neighbor 33.1.1.1 remote-as 100
neighbor 33.1.1.1 update-source l0
exit
R1/R3:
router bgp 100
neighbor 22.1.1.1 remote-as 100
neighbor 22.1.1.1 update-source l0
exit
R3:
router bgp 100
no synchronization
exit
ping 100.1.1.1
4.用peer-group的方法建立邻居关系
---------------------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 23.1.1.0 0.0.0.255
network 22.1.1.0 0.0.0.255
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
int l0
ip add 33.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 23.1.1.0 0.0.0.255
network 33.1.1.0 0.0.0.255
exit
R1:
router bgp 100
bgp router-id 11.1.1.1
neighbor IBGP peer-group
neighbor IBGP remote-as 100
neighbor IBGP update-source l0
neighbor IBGP next-hop-self
neighbor 22.1.1.1 peer-group IBGP
neighbor 33.1.1.1 peer-group IBGP
exit
R2:
router bgp 100
bgp router-id 22.1.1.1
neighbor IBGP peer-group
neighbor IBGP remote-as 100
neighbor IBGP update-source l0
neighbor IBGP next-hop-self
neighbor 11.1.1.1 peer-group IBGP
neighbor 33.1.1.1 peer-group IBGP
exit
R3:
router bgp 100
bgp router-id 33.1.1.1
neighbor IBGP peer-group
neighbor IBGP remote-as 100
neighbor IBGP update-source l0
neighbor IBGP next-hop-self
neighbor 22.1.1.1 peer-group IBGP
neighbor 11.1.1.1 peer-group IBGP
exit
5.BGP的自动汇总
----------------------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 22.1.1.0 0.0.0.255
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
R1:
router bgp 100
no synchronization
no auto-summary
bgp router-id 11.1.1.1
neighbor 22.1.1.1 remote-as 100
neighbor 22.1.1.1 update-source l0
neighbor 22.1.1.1 next-hop-self
exit
R2:
router bgp 100
bgp router-id 22.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
neighbor 11.1.1.1 next-hop-self
neighbor 23.1.1.3 remote-as 200
exit
R3:
router bgp 200
bgp router-id 33.1.1.1
neighbor 23.1.1.2 remote-as 100
exit
int l1
ip add 100.1.1.1 255.255.255.0
no shut
exit
int l2
ip add 100.1.2.1 255.255.255.0
no shut
exit
int l3
ip add 100.1.3.1 255.255.255.0
no shut
exit
router bgp 200
auto-summary
network 100.1.1.0 mask 255.255.255.0
network 100.1.2.0 mask 255.255.255.0
network 100.1.3.0 mask 255.255.255.0
exit
R2:
show ip bgp
R3:
router bgp 200
network 100.0.0.0
exit
R2:
show ip bgp
router bgp 100
auto-summary
redistribute eigrp 1
exit
show ip bgp
6.BGP手动汇总(地址汇聚)
---------------------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 22.1.1.0 0.0.0.255
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
R1:
router bgp 100
no auto-summary
bgp router-id 11.1.1.1
neighbor 22.1.1.1 remote-as 100
neighbor 22.1.1.1 update-source l0
neighbor 22.1.1.1 next-hop-self
exit
R2:
router bgp 100
no auto-summary
bgp router-id 22.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
neighbor 11.1.1.1 next-hop-self
neighbor 23.1.1.3 remote-as 200
exit
R3:
router bgp 200
no auto-summary
bgp router-id 33.1.1.1
neighbor 23.1.1.2 remote-as 100
exit
int l1
ip add 100.1.1.1 255.255.255.0
no shut
exit
int l2
ip add 100.1.2.1 255.255.255.0
no shut
exit
int l3
ip add 100.1.3.1 255.255.255.0
no shut
exit
router bgp 200
network 100.1.1.0 mask 255.255.255.0
network 100.1.2.0 mask 255.255.255.0
network 100.1.3.0 mask 255.255.255.0
exit
R2:
router bgp 100
aggregate-address 100.1.0.0 255.255.0.0
exit
R1/R2:
show ip bgp
R2:
router bgp 100
aggregate-address 100.1.0.0 255.255.0.0 summary-only
exit
R1/R2:
show ip bgp
R2:
ip prefix-list CISCO permit 100.1.1.0/24
ip prefix-list CISCO permit 100.1.2.0/24
route-map YESLAB permit 10
match ip add prefix-list CISCO
exit
router bgp 100
aggregate-add 100.1.0.0 255.255.0.0 suppress-map YESLAB
exit
clear ip bgp *
R1/R3:
show ip bgp
R2:
router bgp 100
aggregate-add 100.1.0.0 255.255.0.0 suppress-map YESLAB as-set
exit
R1/R3:
show ip bgp
R3:
ip prefix-list CISCO1 permit 100.1.1.0/24
ip prefix-list CISCO2 permit 100.1.2.0/24
route-map YESLAB permit 10
match ip add prefix-list CISCO1
set community 200:1
match ip add prefix-list CISCO2
set community 200:2
exit
route-map YESLAB permit 9999
exit
router bgp 200
neighbor 23.1.1.2 route-map YESLAB out
neighbor 23.1.1.2 send-community
exit
ip bgp-community new-format
clear ip bgp * soft out
R2:
ip bgp-community new-format
show ip bgp 100.1.1.0
show ip bgp 100.1.2.0
show ip bgp 100.1.0.0
R1:
show ip bgp 100.1.0.0
R2:
ip prefix-list 200.1 deny 100.1.2.0/24
ip prefix-list 200.1 permit 0.0.0.0/0 le 32
route-map ADV permit 10
match ip address prefix-list 200.1
exit
router bgp 100
aggregate-add 100.1.0.0 255.255.0.0 as-set advertise-map ADV suppress-map YESLAB
show ip bgp
R2:
route-map SET permit 10
set community 100:100 additive
exit
router bgp 100
aggregate-add 100.1.0.0 255.255.0.0 as-set attribute-map SET advertise-map ADV suppress-map YESLAB
exit
show ip bgp 100.1.0.0
7.产生默认路由
-----------------------------------------------------------------
R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 11.1.1.0 0.0.0.255
exit
R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
router eigrp 1
no auto-summary
network 12.1.1.0 0.0.0.255
network 22.1.1.0 0.0.0.255
exit
R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
R1:
router bgp 100
no auto-summary
bgp router-id 11.1.1.1
neighbor 22.1.1.1 remote-as 100
neighbor 22.1.1.1 update-source l0
neighbor 22.1.1.1 next-hop-self
exit
R2:
router bgp 100
no auto-summary
bgp router-id 22.1.1.1
neighbor 11.1.1.1 remote-as 100
neighbor 11.1.1.1 update-source l0
neighbor 11.1.1.1 next-hop-self
neighbor 23.1.1.3 remote-as 200
exit
R3:
router bgp 200
no auto-summary
bgp router-id 33.1.1.1
neighbor 23.1.1.2 remote-as 100
exit
R1:
ip route 0.0.0.0 0.0.0.0 null 0
router bgp 100
redistribute static
exit
show ip bgp
R1:
router bgp 100
default-information originate
exit
show ip bgp
R1:
no ip route 0.0.0.0 0.0.0.0 null 0
router bgp 100
no redistribute static
no default-information originate
exit
ip route 0.0.0.0 0.0.0.0 12.1.1.2
router bgp 100
network 0.0.0.0
exit
show ip bgp
R1:
no ip route 0.0.0.0 0.0.0.0 12.1.1.2
router bgp 100
no network 0.0.0.0
exit
router bgp 100
neighbor 22.1.1.1 default-originate
exit
R2:
show ip bgp
用此命令时R1上并不会看到任何默认路由。