Reliable Policy Routing
R5 has two loopbacks, 5.5.5.5/32 and 55.55.55.55/32
Configure policy routing on r2 so that:
- to reach 5.5.5.5/32 packets from r1 must go to r3.
- to reach 55.55.55.55/32 packets from r1 must go to r4.
- do not use static routing on r2 (excepted to reach r1).
Use reliable routing to do this:
- if r3 is not reachable, packets to 5.5.5.5/32 must go through r4.
- if r4 is not reachable, packets to 55.55.55.55/32 must go through r3.
Verify using traceroute.
r1 configuration:
!
hostname r1
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface Serial1/0
ip address 192.168.12.1 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 192.168.12.2
!
r2 configuration:
!
hostname r2
!
track 5 ip sla 10
!
track 55 ip sla 15
!
interface Serial1/0
ip address 192.168.12.2 255.255.255.0
ip policy route-map PBR
!
interface Serial1/1
ip address 192.168.23.2 255.255.255.0
serial restart-delay 0
!
interface Serial1/2
ip address 192.168.24.2 255.255.255.0
!
ip route 1.1.1.1 255.255.255.255 192.168.12.1
!
ip sla 10
icmp-echo 192.168.23.3 source-interface Serial1/1
timeout 1000
threshold 1000
frequency 2
ip sla schedule 10 life forever start-time now
ip sla 15
icmp-echo 192.168.24.4 source-interface Serial1/2
timeout 1000
threshold 1000
frequency 2
ip sla schedule 15 life forever start-time now
access-list 105 permit ip any host 5.5.5.5
access-list 155 permit ip any host 55.55.55.55
!
route-map PBR permit 10
match ip address 105
set ip next-hop verify-availability 192.168.23.3 1 track 5
set ip default next-hop 192.168.24.4
!
route-map PBR permit 20
match ip address 155
set ip next-hop verify-availability 192.168.24.4 1 track 55
set ip default next-hop 192.168.23.3
!
r3 configuration:
!
hostname r3
!
interface Serial1/0
ip address 192.168.23.3 255.255.255.0
!
interface Serial1/1
ip address 192.168.35.3 255.255.255.0
!
ip route 1.1.1.1 255.255.255.255 192.168.23.2
ip route 5.5.5.5 255.255.255.255 192.168.35.5
ip route 55.55.55.55 255.255.255.255 192.168.35.5
!
r4 configration:
!
hostname r4
!
interface Serial1/0
ip address 192.168.24.4 255.255.255.0
!
interface Serial1/1
ip address 192.168.45.4 255.255.255.0
!
ip route 1.1.1.1 255.255.255.255 192.168.24.2
ip route 5.5.5.5 255.255.255.255 192.168.45.5
ip route 55.55.55.55 255.255.255.255 192.168.45.5
!
r5 configuration:
!
hostname r5
!
interface Loopback0
ip address 5.5.5.5 255.255.255.255
!
interface Loopback1
ip address 55.55.55.55 255.255.255.255
!
interface Serial1/0
ip address 192.168.35.5 255.255.255.0
!
interface Serial1/1
ip address 192.168.45.5 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 192.168.45.4
!
Verifications:
r1#traceroute 5.5.5.5 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 5.5.5.5
1 192.168.12.2 8 msec 24 msec 20 msec
2 192.168.23.3 20 msec 44 msec 44 msec
3 192.168.35.5 76 msec * 64 msec
r1#traceroute 55.55.55.55 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 55.55.55.55
1 192.168.12.2 24 msec 20 msec 20 msec
2 192.168.24.4 20 msec 44 msec 40 msec
3 192.168.45.5 80 msec * 76 msec
Now, on r3, remove IP address 192.168.23.3:
On r2, you see :
Feb 23 01:06:28.127: %TRACKING-5-STATE: 5 ip sla 10 state Up->Down
r1#traceroute 5.5.5.5 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 5.5.5.5
1 192.168.12.2 16 msec 24 msec 20 msec
2 192.168.24.4 24 msec 36 msec 44 msec
3 192.168.45.5 76 msec * 72 msec
r1#traceroute 55.55.55.55 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 55.55.55.55
1 192.168.12.2 24 msec 20 msec 24 msec
2 192.168.24.4 36 msec 24 msec 44 msec
3 192.168.45.5 76 msec * 76 msec
Note:
If you remove IP 192.168.24.4 on r4, configure the default route in r5 via r3...
On r3, add IP address 192.168.23.3:
On r2, you see:
Feb 23 01:10:18.127: %TRACKING-5-STATE: 5 ip sla 10 state Down->Up
r1#traceroute 5.5.5.5 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 5.5.5.5
1 192.168.12.2 28 msec 16 msec 24 msec
2 192.168.23.3 24 msec 40 msec 40 msec
3 192.168.35.5 80 msec * 64 msec
r1#traceroute 55.55.55.55 source 1.1.1.1
Type escape sequence to abort.
Tracing the route to 55.55.55.55
1 192.168.12.2 20 msec 20 msec 24 msec
2 192.168.24.4 16 msec 44 msec 44 msec
3 192.168.45.5 56 msec * 40 msec
