Configuration examples Route Map and Policy-Based Routing

This article will show how to use Policy-Based Routing to different default routes are used based on the source of the ip address. Let me show you the diagram and the configuration step. The example below should cover basic route-map configuration.

The previous diagram illustrates the structure of Route Map and Policy-Based Routing

IP Address Assignment:

• VLAN 10  Management Vlan       IP address: 146.10.50.xx/24
• VLAN 20  Server Vlan                 IP address: 146.20.50.xx/24
• VLAN 30  Wireless Lan VIP        IP address: 146.30.50.xx/24
• VLAN 31  Wireless Lan Visitor    IP address: 146.30.50.xx/24
• VLAN 40  Workstation Vlan         IP address: 146.40.50.xx/24

Step 1 - Defining an ACL
Create a simple ACL:
  SGHQSL1-4506(config)#ip access-list extended WVIP
  SGHQSL1-4506(config-ext-nacl)# permit ip host 146.30.50.31 any
  SGHQSL1-4506(config-ext-nacl)# permit ip host 146.30.50.32 any
  SGHQSL1-4506(config)#ip access-list extended WVISITOR
  SGHQSL1-4506(config-ext-nacl)# permit ip 146.31.50.65 any

Step 2 - Creating a route-map
To create a route-map, go into route-map configuration mode, like this:
  SGHQSL1-4506(config)#route-map InternetWVISITOR permit 5
  SGHQSL1-4506(config-route-map) #match ip address WVISITOR
  SGHQSL1-4506(config-route-map) #set ip next-hop 146.10.50.15 
  SGHQSL1-4506(config)#route-map InternetWVIP permit 10
  SGHQSL1-4506(config-route-map) #match ip address WVIP
  SGHQSL1-4506(config-route-map) #set ip next-hop 146.10.50.12 
In this example, this will match all the traffic permitted through access-list WVIP change the next-hop to 146.10.050.12 and all the traffice permitted through access-list WVISITOR change the next-hop to 146.10.50.15

Step 3 - Applying the route-map to the interface
Next, you need to apply this policy/route-map to the interface where the traffic is coming in.
  SGHQSL1-4506(config)#interface Vlan30
  SGHQSL1-4506(config-if)#ip policy route-map InternetWVIP
  SGHQSL1-4506(config)#interface Vlan31
  SGHQSL1-4506(config-if)#ip policy route-map InternetWVISITOR

Some helpful commands to monitor and verify the access list, route-map and ip policy.
SGHQSL1-4506#sh ip policy
Interface      Route map
Vlan30         InternetWVIP
Vlan31         InternetWVISITOR

SGHQSL1-4506#sh route-map
route-map InternetWVIP, permit, sequence 10
  Match clauses:
    ip address (access-lists): VIP
  Set clauses:
    ip next-hop 146.10.50.12
  Policy routing matches: 17846460 packets, 2246593826 bytes
route-map InternetWVISITOR, permit, sequence 10
  Match clauses:
    ip address (access-lists): wlan
  Set clauses:
    ip next-hop 146.10.50.15
  Policy routing matches: 2450155 packets, 322873006 bytes

SGHQSL1-4506#sh access-lists WVIP
Extended IP access list WVIP
    10 permit ip host 146.30.50.31 any
    20 permit ip host 146.30.50.32 any (278 matches)
SGHQSL1-4506#sh access-lists WVISITOR
Extended IP access list WVISITOR
    10 permit ip 146.31.50.65 0.0.0.255 any (2470017 matches)
Note: The traffic that does not match the policy uses the default route configured in the core switch.

Read More