daknetworks.com

You are here: Blog MPLS Connection Cisco Routes

MPLS Connection Cisco Routes

So routes in an MPLS cisco router can have the following codes; the highlighted ones are the most common I see:

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

As elsewhere, you can see the routes by:

show ip route

Or you can search for a route by (ie search for routes to 10.116.x.x):

show ip route | incude 116

 To add a route to the MPLS router nodes, the route must be added as a STATIC route to the node that is LOCAL to the subnet.

For example, we add a new node to the MPLS network. That new node has the following network as a LOCAL subnet: 10.116.0.10/32.

This network would show as the following:

L        10.116.0.10/32 is directly connected, GigabitEthernet0/1

The new node also has the following network as a subnet 10.116.15.0/24. The problem is that while the subnet at the location will already know about the subnet, the other locations will not know about the subnet until it is advertised/distributed across the MPLS network routers.

If you try to traceroute a address on the new subnet from a different location, the other routers will not know what to do and bounce the packet to the default route, causing a loop/bounce.

As stated above, to resolve, the STATIC route must be added to the router where the subnet is located:

S        10.116.15.0/24 [1/0] via 10.116.1.1

Once that is added, the other routers will pickup the route as a BGP route:

B        10.116.15.0/24 [20/0] via 10.162.131.38

Contact Dak Networks

Please contact us at the following.