route-map magic permit 10
Duct tape has now become multipurpose and is used for general sealing, patching holes, packing boxes and repairs.
One of my favorite tools especially when using Cisco devices is route-map!
I love route-map! Everywhere route-map!
Route maps are like duct tape or swiss-army knife for the network—they can be applied to numerous situations to address many issues. At times, they may not be the most "pretty solutions," but they will be very effective in terms of workaround.
Being part of network engineering and operation team, I need to balance between the two devils. I need to ensure my network operation working as expected as well new business challenges and requirement met along the day.
This is some of my story behind the scenes:
I’ve made some changes on the PE103. During the redistribution from BGP to OSPF, I have block the update. So far, I’ve tested to passive the interface at CE and “no network command at PE103” to simulate network advertisement withdrawn . Seems it does it my duck tape (route-map!) and ospf database external works! Always remember, there are two mutual redistribution happen here. Some of the attribution might loss during the transition. Use with caution.Deep dive understanding your requirement before apply.
PE103#sh run | be router ospf 10
router ospf 10 vrf V267:ABC
redistribute bgp 20 metric-type 1 subnets route-map ABC
!
PE103#sh route-map ABC
route-map ABC, permit, sequence 10
Match clauses:
ip address (access-lists): ABC
Set clauses:
Policy routing matches: 0 packets, 0 bytes
*Mar 26 00:49:45.178: %SYS-5-CONFIG_I: Configured from console by vty0
*Mar 26 00:50:45.491: %OSPF-5-ADJCHG: Process 10, Nbr X.X.X.X on Serial0/0/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Mar 26 00:50:51.697: Track: 1 Change #38 IP route X.X.X.X/30, OSPF->no route, reachability Up->Down
*Mar 26 00:52:28.898: %OSPF-5-ADJCHG: Process 10, Nbr X.X.X.X.X on Serial0/0/0 from LOADING to FULL, Loading Done
*Mar 26 00:52:30.349: %SYS-5-CONFIG_I: Configured from console by vty0
*Mar 26 00:52:44.880: Track: 1 Change #39 IP route X.X.X.X, no route->OSPF, reachability Down->Up
Don't forget to turn on the necessary debug command. Don't debug all in operation!
Another scenario, when I have complex BGP fully mesh inter-connectivity and don't want the desired routing determine the route by itself, route-map is called in order in to break and configured according to requirements.
CE2
!
router bgp 65003
neighbor 192.168.20.5 default-originate route-map DEFAULT-ROUTE-TO-CE1
neighbor 192.168.20.18 remote-as 65001
neighbor 192.168.20.18 default-originate route-map DEFAULT-ROUTE
neighbor 192.168.20.22 remote-as 65002
neighbor 192.168.20.22 default-originate route-map DEFAULT-ROUTE
!
route-map DEFAULT-ROUTE-TO-CE1 permit 10
set local-preference 90
!
route-map DEFAULT-ROUTE permit 10
set as-path prepend 65003
What's the most complex scenario that you ever faced before and use route-map for workaround? How do you use your duct tape to solve your situations?