PRIMARY & SECONDARY PATH USING STATIC ROUTE


TOPIC

SCENARIO

CONFIGURATION

VERIFICATION

POSSIBLE ERROR WITH EXAMPLE

 


 

SCENARIO

Source is Our Company, AB

Destination is Another Company, ER

Paths to Reach Destination: One is through Location A  &  Location B 

Requirement is to make Location A: Primary  &   Location B: Secondary

Subnet Related to the Company, ER are 192.168.172.0/24 & 192.168.175.0/24


 

CONFIGURATION

We have to play around with the Static Routes

We will add Static Routes on both the location, location A & Location B  in little bit different way.

 

KEY POINT

If we have two routes or simply two paths to reach Destination, More specific route or path will be considered

 

At Location A

Add Static routes for subnets 192.168.172.0/24 & 192.168.175.0/24 with more specific route.

So, More preferred

At Location B

Add Static routes for subnets 192.168.172.0/24 & 192.168.175.0/24 as it is. So, Less Preferred

 

 

At Location A, Static Route Configuration

ip route  192.168.172.51  255.255.255.255 10.149.194.10

ip route  192.168.175.51  255.255.255.255 10.149.194.10

At Location B, Static Route Configuration

ip route  192.168.172.0  255.255.255.0 10.149.28.10

ip route  192.168.175.0  255.255.255.0 10.149.28.10

 

 

LOCATION A, COMPLETE CONFIGURATION

ROUTE MAP DETAILS

redistribute static metric-type 1 subnets route-map static-to-ospf

route-map static-to-ospf permit 10

match ip address prefix-list static-nets

route-map static-to-ospf deny 20

 

PREFIX LIST DETAILS ( New Subnets belonging to Company, ER needs to be permitted)

ip prefix-list static-nets seq 40 permit 192.168.175.51/32

ip prefix-list static-nets seq 50 permit 192.168.172.51/32

 

STATIC ROUTE DETAILS

ip route 192.168.172.51  255.255.255.255  10.149.194.10

ip route 192.168.175.51  255.255.255.255  10.149.194.10

LOCATION B, COMPLETE CONFIGURATION

ROUTE MAP DETAILS

route-map Static_To_OSPF_Filter permit 10

match ip address prefix-list Static_To_OSPF

route-map Static_To_OSPF_Filter deny 20

 

PREFIX LIST

ip prefix-list Static_To_OSPF seq 10 permit 10.10.40.0/24

ip prefix-list Static_To_OSPF seq 20 permit 10.149.32.0/24

ip prefix-list Static_To_OSPF seq 30 permit 10.149.38.0/26

ip prefix-list Static_To_OSPF seq 40 permit 10.149.41.0/28

 

STATIC ROUTE DETAILS

ip route 192.168.172.0 255.255.255.0 10.149.28.10

ip route 192.168.175.0 255.255.255.0 10.149.28.10


 

VERIFICATION

core_1#traceroute 192.168.172.51

  1 10.146.1.18 0 msec 0 msec 0 msec
  2 10.146.192.142 0 msec 0 msec 0 msec
  3 10.146.192.145 4 msec 0 msec 0 msec
  4 67.69.208.213 32 msec 28 msec 28 msec
  5 67.69.207.130 16 msec 12 msec 12 msec
  6 10.149.195.222 44 msec 44 msec 44 msec
  7 10.149.195.145 48 msec 48 msec 44 msec   < ———–  Belongs to Location A

CONCLUSION

Now, it is confirmed, Path through Location A is chosen as the Primary path to reach destination

Company, ER

 ************************

 

POSSIBLE ERROR WITH EXAMPLE

In Static Route, Next Hop is always connected device.

If Next Hop is not correctly given in Static Route, Next device will not be found.

Below is given the example output

1#traceroute 192.168.172.51
1 10.146.1.18 0 msec 0 msec 0 msec
2 10.146.192.142 0 msec 4 msec 0 msec
3 10.146.192.145 0 msec 0 msec 0 msec
4 67.69.208.213 20 msec 20 msec 20 msec
5 67.69.207.130 16 msec 16 msec 16 msec
6 10.149.253.85 [MPLS: Label 16916 Exp 0] 56 msec 64 msec 60 msec
7 10.149.253.86 52 msec 56 msec 48 msec
8 10.149.253.251 48 msec 52 msec 44 msec
9 10.149.253.253 64 msec 60 msec 60 msec
10 10.149.253.251 48 msec 48 msec 52 msec
11 10.149.253.253 60 msec 60 msec 64 msec
*************************
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