RIP: Filtering using distribute-list
·
We
can filter the routes in RIP using distribute-list
·
Let
me take a small topology to configure route filtering in RIP
R1------S1/0-------------s1/0----R2
10.1.12.1--------------10.1.12.2
R1(config-router)#do show run | sec router
router
rip
version 2
network 1.0.0.0
network 10.0.0.0
network 11.0.0.0
network 111.0.0.0
no auto-summary
R1(config-router)#
R2#show run | sec router
router
ospf 1
log-adjacency-changes
router
rip
version 2
network 2.0.0.0
network 10.0.0.0
no auto-summary
R2#
R1(config-router)#do show ip route
Codes:
C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route
Gateway
of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1] via 10.1.12.2, 00:00:18,
Serial1/0
111.0.0.0/32 is subnetted, 1 subnets
C 111.111.111.111 is directly connected,
Loopback2
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.12.0 is directly connected,
Serial1/0
11.0.0.0/32 is subnetted, 1 subnets
C 11.11.11.11 is directly connected,
Loopback1
R1(config-router)#
R2#show ip route
Codes:
C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route
Gateway
of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
R
1.1.1.1 [120/1] via 10.1.12.1, 00:00:04, Serial1/0
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
111.0.0.0/32 is subnetted, 1 subnets
R
111.111.111.111 [120/1] via 10.1.12.1, 00:00:04, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.12.0 is directly connected,
Serial1/0
11.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
R
11.11.11.11/32 [120/1] via 10.1.12.1, 00:00:04, Serial1/0
C 11.1.23.0/24 is directly connected,
Serial1/1
R2#
Observation:
·
RIP
is configured between R1 and R2
·
R1
has advertised its loopback0 1.1.1.1/32 into RIP
·
R1
has advertised its loopback0 11.11.11.11/32 into RIP
·
R1
has advertised its loopback0 111.111.111.111/32 into RIP
·
R2
has advertised its loopback0 2.2.2.2/32 into RIP
·
Now,
If R2 wants only 111.111.111.111/32 route??
·
Let
me configure this in R2
·
Prefix-list
should match only 111.111.111.111/32
R2(config)#ip
prefix-list 111 seq 5 permit 111.111.111.111/32
R2(config)#router
rip
R2(config-router)#distribute-list
prefix 111 in serial 1/0
R2(config-router)#
R2#show ip
route
Codes:
C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route
Gateway
of last resort is not set
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
111.0.0.0/32 is subnetted, 1 subnets
R
111.111.111.111 [120/1] via
10.1.12.1, 00:00:24, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.12.0 is directly connected,
Serial1/0
11.0.0.0/24 is subnetted, 1 subnets
C 11.1.23.0 is directly connected,
Serial1/1
R2#
Observation:
·
R2
sees only 111.111.111.111/32 from R1 now.
No comments:
Post a Comment