We all know policy route rules the router. It has even greater
priority than connected route. How to make other routes on the routing tables which can have greater
priority than policy route. How to do it?
Following the scenario to do the above difficult but possible stuff.
The above diagram shows there are two path to reach from
router R1 loopback address i.e. 30.30.30.1 to router R3 loopback address
40.40.40.1. One is via R1----R2------R3 & the other is via
R1----R2-----R4----R3. We have policy map enforce (next hop for 40.40.40.1
towards R4) on router R2 i.e. on F0/0 interface. Still packet moving towards R3
via f0/1 interface of router R2. Check(Scenario 1) the trace route which is now
moving via router R2----R3 even the policy route map enforce on the router R2
interface F0/0.
Now I will shut down f0/1 interface of router R3 which will
stop direct connectivity between Router R2 and R3. Now check Scenario 2. Now the
traffic moving via R1-R2-R4-R3. How it is possible. The command “set ip default
next-hop” is the do the job for us. If you use the syntax default then Policy route will active in case of there is no route
in the routing table for the next hop network. Kindly find the configuration of all the routers below &
try it by yourself.
Scenario 1
interface FastEthernet0/0
ip address 10.10.10.2
255.255.255.0
ip policy route-map
san
duplex auto
speed auto
-------
route-map san permit 10
match ip address ss
set ip default
next-hop 10.10.30.2
R1#traceroute
Protocol [ip]:
Target IP address: 40.40.40.1
Source address: 30.30.30.1
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]:
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to 40.40.40.1
1 10.10.10.2 32 msec
12 msec 12 msec
2 10.10.20.2 28 msec
24 msec 20 msec
Scenario 2
R3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#int f0/1
R3(config-if)#shut
R3(config-if)#
*Mar 1 01:40:02.099:
%DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.10.20.1 (FastEthernet0/1) is
down: interface down
R3(config-if)#
*Mar 1 01:40:04.007:
%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to administratively
down
*Mar 1 01:40:05.007:
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state
to down
R1#traceroute
Protocol [ip]:
Target IP address: 40.40.40.1
Source address: 30.30.30.1
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]:
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to 40.40.40.1
1 10.10.10.2 20 msec
12 msec 12 msec
2 10.10.30.2 32 msec
20 msec 44 msec
3 11.11.11.2 44 msec
48 msec 24 msec
R1
R1#sh run
Building configuration...
Current configuration : 1104 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
!
archive
log config
hidekeys
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
interface Loopback0
ip address 30.30.30.1
255.255.255.0
!
interface FastEthernet0/0
ip address 10.10.10.1
255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
no ip address
shutdown
duplex auto
speed auto
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 10.10.10.2
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R2
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
no ip domain lookup
!
multilink bundle-name authenticated
archive
log config
hidekeys
!
ip tcp synwait-time 5
ip ssh version 1
!
interface FastEthernet0/0
ip address 10.10.10.2
255.255.255.0
ip policy route-map
san
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.10.20.1
255.255.255.0
duplex auto
speed auto
!
interface FastEthernet1/0
ip address 10.10.30.1
255.255.255.0
duplex auto
speed auto
!
router eigrp 100
redistribute static
network 10.0.0.0
auto-summary
!
ip forward-protocol nd
ip route 30.30.30.0 255.255.255.0 10.10.10.1
!
!
no ip http server
no ip http secure-server
!
ip access-list extended ss
permit ip 30.30.30.0
0.0.0.255 40.40.40.0 0.0.0.255
!
no cdp log mismatch duplex
!
route-map san permit 10
match ip address ss
set ip default
next-hop 10.10.30.2
!
control-plane
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R3
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
archive
log config
hidekeys
!
ip tcp synwait-time 5
ip ssh version 1
!
interface Loopback0
ip address 40.40.40.1
255.255.255.0
!
interface FastEthernet0/0
ip address 11.11.11.2
255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.10.20.2
255.255.255.0
duplex auto
speed auto
!
interface FastEthernet1/0
no ip address
shutdown
duplex auto
speed auto
!
router eigrp 100
network 10.0.0.0
network 40.0.0.0
auto-summary
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 11.11.11.1
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R4
R4#sh run
Building
configuration...
Current
configuration : 1111 bytes
!
version 12.4
service
timestamps debug datetime msec
service
timestamps log datetime msec
no service
password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa
new-model
memory-size
iomem 5
no ip icmp
rate-limit unreachable
ip cef
!
no ip domain
lookup
!
multilink
bundle-name authenticated
!
!
archive
log config
hidekeys
!
!
ip tcp
synwait-time 5
ip ssh
version 1
!
interface
FastEthernet0/0
ip address 11.11.11.1 255.255.255.0
duplex auto
speed auto
!
interface
FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface
FastEthernet1/0
ip address 10.10.30.2 255.255.255.0
duplex auto
speed auto
!
ip
forward-protocol nd
ip route
30.30.30.0 255.255.255.0 10.10.30.1
ip route
40.40.40.0 255.255.255.0 11.11.11.2
!
!
no ip http
server
no ip http
secure-server
!
no cdp log
mismatch duplex
!
control-plane
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
No comments:
Post a Comment