Policy based routing is use to path manipulation. It is used for implementing policy that causes the packet to
take a different direction. Policy based routing allows source based routing. Routing
table is destination base.
In short: PBR
is a technique used to make routing decisions based on policies implemented by
the network administrator.
Here’s the list of some Advantages of policy based routing:-
- Different users can reach the destination from different direction
- Load sharing
- PBR will be implemented on the incoming direction of the source in interface
- If the packet is match in the route map and it is permit it will be send according to the policy
- If the packet is match in the route map and route map deny packet will be forwarded according to normal routing table
Topology:-
Goal:-
- configure the topology as per our diagram
- configure EIGRP 100 all the routers, advertise all the interfaces as per the topology make sure the rechibility between all the routers.
- configure the bandwidth on serial 3/3 to 1000kbps and serial 3/0 remain the default bandwidth 1544 kbps.
- configure Policy Based Routing on router 2 according to our given conditions
- traffic sourced from 13.0.0.0/24, 13.0.1.0/24 should be forwarded on serial 3/0 interface
- traffic sourced from 13.0.2.0/24, 13.0.3.0/24 should be forwarded on serial 3/3 interface
- all the remaining traffic should use the default routing path
R1(config)#router eigrp 100
R1(config-router)#network 11.0.0.0
R1(config-router)#network 1.0.0.0
R1(config-router)#network 3.0.0.0
R1(config-router)#network 10.0.0.0
R1(config-router)#no auto-summary
R1(config-router)#end
R2(config)#router eigrp 100
R2(config-router)#network 1.0.0.0
R2(config-router)#network 3.0.0.0
R2(config-router)#network 3.0.0.0
R2(config-router)#network 20.0.0.0
R2(config-router)#no auto-summary
R3(config)#router eigrp 100
R3(config-router)#network 20.0.0.0
R3(config-router)#network 20.0.0.0
R3(config-router)#network 13.0.0.0
R3(config-router)#no auto-summary
R3(config-router)#end
R2#show ip eigrp 100 neighbors
EIGRP-IPv4 Neighbors for AS(100)
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
2 20.1.1.3 Fa0/0 13 00:06:27 16 100 0 4
1 3.1.1.1 Se3/3 11 00:07:02 16 100 0 8
0 1.1.1.1 Se3/0 13 00:07:05 669 4014 0 7
R2#show ip route eigrp
Codes: L - local, 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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
D 10.0.0.0/8 [90/2172416] via 3.1.1.1, 00:10:32, Serial3/3
[90/2172416] via 1.1.1.1, 00:10:32, Serial3/0
11.0.0.0/24 is subnetted, 4 subnets
D 11.0.0.0 [90/2297856] via 3.1.1.1, 00:10:32, Serial3/3
[90/2297856] via 1.1.1.1, 00:10:32, Serial3/0
D 11.0.1.0 [90/2297856] via 3.1.1.1, 00:10:32, Serial3/3
[90/2297856] via 1.1.1.1, 00:10:32, Serial3/0
D 11.0.2.0 [90/2297856] via 3.1.1.1, 00:10:32, Serial3/3
[90/2297856] via 1.1.1.1, 00:10:32, Serial3/0
D 11.0.3.0 [90/2297856] via 3.1.1.1, 00:10:32, Serial3/3
[90/2297856] via 1.1.1.1, 00:10:32, Serial3/0
13.0.0.0/24 is subnetted, 4 subnets
D 13.0.0.0 [90/156160] via 20.1.1.3, 00:09:48, FastEthernet0/0
D 13.0.1.0 [90/156160] via 20.1.1.3, 00:09:48, FastEthernet0/0
D 13.0.2.0 [90/156160] via 20.1.1.3, 00:09:48, FastEthernet0/0
D 13.0.3.0 [90/156160] via 20.1.1.3, 00:09:48, FastEthernet0/0
R2(config)#int serial 3/3
R2(config-if)#bandwidth 1000
R2(config-if)#exit
R2#show ip route eigrp
Codes: L - local, 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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
D 10.0.0.0/8 [90/2172416] via 1.1.1.1, 00:00:48, Serial3/0
11.0.0.0/24 is subnetted, 4 subnets
D 11.0.0.0 [90/2297856] via 1.1.1.1, 00:00:48, Serial3/0
D 11.0.1.0 [90/2297856] via 1.1.1.1, 00:00:48, Serial3/0
D 11.0.2.0 [90/2297856] via 1.1.1.1, 00:00:48, Serial3/0
D 11.0.3.0 [90/2297856] via 1.1.1.1, 00:00:48, Serial3/0
13.0.0.0/24 is subnetted, 4 subnets
D 13.0.0.0 [90/156160] via 20.1.1.3, 00:12:19, FastEthernet0/0
D 13.0.1.0 [90/156160] via 20.1.1.3, 00:12:19, FastEthernet0/0
D 13.0.2.0 [90/156160] via 20.1.1.3, 00:12:19, FastEthernet0/0
D 13.0.3.0 [90/156160] via 20.1.1.3, 00:12:19, FastEthernet0/0
R2(config)#access-list 10 per
R2(config)#access-list 10 permit 13.0.0.0 0.0.0.255
R2(config)#access-list 10 permit 13.0.1.0 0.0.0.255
R2(config)#access-list 12 permit 13.0.2.0 0.0.0.255
R2(config)#access-list 12 permit 13.0.3.0 0.0.0.255
R2(config)#route-map PBR permit 10
R2(config-route-map)#match ip address 10
R2(config-route-map)#set ip next-hop 1.1.1.1
R2(config-route-map)#exit
R2(config)#route-map PBR permit 12
R2(config-route-map)#match ip address 12
R2(config-route-map)#set ip next-hop 3.1.1.1
R2(config-route-map)#exit
R2(config)#interface fastEthernet 0/0
R2(config-if)#ip policy route-map PBR
R2(config-if)#exit
R3#traceroute 11.0.0.1 source 13.0.0.1
Type escape sequence to abort.
Tracing the route to 11.0.0.1
VRF info: (vrf in name/id, vrf out name/id)
1 20.1.1.1 16 msec 20 msec 20 msec
2 1.1.1.1 88 msec 28 msec 32 msec
R3#traceroute 11.0.0.1 source 13.0.1.1
Type escape sequence to abort.
Tracing the route to 11.0.0.1
VRF info: (vrf in name/id, vrf out name/id)
1 20.1.1.1 16 msec 16 msec 24 msec
2 1.1.1.1 40 msec 32 msec 20 msec
R3#traceroute 11.0.0.1 source 13.0.2.1
Type escape sequence to abort.
Tracing the route to 11.0.0.1
VRF info: (vrf in name/id, vrf out name/id)
1 20.1.1.1 16 msec 20 msec 28 msec
2 3.1.1.1 52 msec 44 msec 40 msec
R3#traceroute 11.0.0.1 source 13.0.3.1
Type escape sequence to abort.
Tracing the route to 11.0.0.1
VRF info: (vrf in name/id, vrf out name/id)
1 20.1.1.1 24 msec 8 msec 24 msec
2 3.1.1.1 32 msec 44 msec 44 msec
R2#debug ip policy
Policy routing debugging is on
*Nov 23 15:57:46.706: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1, len 28, policy match
*Nov 23 15:57:46.706: IP: route map PBR, item 10, permit
*Nov 23 15:57:46.710: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1 (Serial3/0), len 28, policy r outed
*Nov 23 15:57:46.710: IP: FastEthernet0/0 to Serial3/0 1.1.1.2
*Nov 23 15:57:46.726: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1, len 28, policy match
*Nov 23 15:57:46.730: IP: route map PBR, item 10, permit
*Nov 23 15:57:46.730: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1 (Serial3/0), len 28, policy r outed
*Nov 23 15:57:46.730: IP: FastEthernet0/0 to Serial3/0 1.1.1.2
*Nov 23 15:57:46.758: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1, len 28, policy match
*Nov 23 15:57:46.758: IP: route map PBR, item 10, permit
*Nov 23 15:57:46.758: IP: s=13.0.0.1 (FastEthernet0/0), d=11.0.0.1 (Serial3/0), len 28, policy r outed
*Nov 23 15:57:46.758: IP: FastEthernet0/0 to Serial3/0 1.1.1.2
*Nov 23 15:57:46.778: IP: s=13.0.0.1 (FastEthernet0/
R2#0), d=11.0.0.1, len 28, FIB policy match
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