03-16-2018 04:48 PM - edited 03-05-2019 10:07 AM
Please see attached pdf file for network topology detail.
In example, we have 2 sites, corporate and branch office.
What they'd like to accomplish;
Configuration Example
B.2
#router ospf 1
#router-id 10.2.1.2
#network 10.2.0.0 0.0.255.255 area 20
#redistribute static
#ip route 0.0.0.0 0.0.0.0 to B.1
B.3
#router ospf 1
#router-id 10.2.1.3
#network 10.2.0.0 0.0.255.255 area 20
#network 10.2.1.0 0.0.255.255 area 20
A.2
#router ospf 1
#router-id 10.1.1.2
#network 10.1.0.0 0.0.255.255 area 10
#redistribute static
#ip route 0.0.0.0 0.0.0.0 to A.1
A.3
#router ospf 1
#router-id 10.1.1.3
#network 10.1.0.0 0.0.255.255 area 10
#network 10.1.1.0 0.0.255.255 area 10
Can you please suggest configuration changes to meet three requirements above?
Thank you
03-16-2018 06:11 PM - edited 03-16-2018 06:13 PM
Hi
are you able to manage B.4? It is just an idea, but have you considered conditional advertising on B.4
Other way could be using IP SLA icmp-echo + track + EEM scripts.
03-16-2018 06:40 PM
Julio,
Thanks for your response. Please see my answers to your questions.
Are you able to manage B.4 (No, it's managed by ISP)? It is just an idea, but have you considered conditional advertising on B.4
Other way could be using IP SLA icmp-echo + track + EEM scripts. Can you please elaborate?
03-16-2018 06:47 PM - edited 03-16-2018 06:48 PM
Hi
OSPF Conditional works as following:
access-list 10 host 1.1.1.1
route-map CONDITION permit 5
match ip address 10
router ospf 100
default-information originate always route-map CONDITION
This router will advertise a default route to its neighbors when the IP 1.1.1.1/32 has an entry into the local routing table. If it does not exist the router will not advertise a default route to its neighbors. The 'always' word is used to advertise a default route with or without a static default route.
:-)
03-16-2018 07:22 PM - edited 03-16-2018 07:25 PM
Now for example, if you want to create a backup path through the MPLS once the primary Path (B1 - B2) is down, you could apply this configuration on B.3
* Take in consideration a default static route is preferred over a default route advertised by any routing protocol unless you change the AD over the static route hehe *
Step 1) Create an IP SLA, it will be making ping to the IP on B.1 facing to B.2 with a frecuency of 5 seconds.
ip sla 1
icmp-echo <B.1 interface IP facing to B.2>
frequency 5
Step 2) Enable the IP SLA
ip sla schedule 1 life forever start-time now
Step3) Track the status of SLA, it will generate a notification after 2 seconds once the ICMP is lost (IP SLA ping)
track 1 rtr 1
delay down 2
Step 4) Create the EEM Scripts, you can create 2 scripts like I did, the first: FAILOVER will create a default route through the MPLS once the message "%TRACKING-5-STATE: 1 rtr 1 state Up->Down" is received on the router. I suggest configure the logging parameters.
The second Script will reestablish the connectivity through B.2 - B.1 once it is up again.
event manager applet FAILOVER
event syslog occurs 1 pattern "%TRACKING-5-STATE: 1 rtr 1 state Up->Down"
action 1.0 cli command "enable"
action 2.0 cli command "conf t"
action 3.0 cli command "ip route 0.0.0.0 0.0.0.0 <Next hop IP through MPLS> name BACKUP"
action 4.0 cli command "write"
event manager applet REESTABLISH
event syslog occurs 1 pattern "%TRACKING-5-STATE: 1 rtr 1 state Down->Up"
action 1.0 cli command "enable"
action 2.0 cli command "conf t"
action 3.0 cli command "no ip route 0.0.0.0 0.0.0.0 <Next hop IP through MPLS> name BACKUP"
action 4.0 cli command "write"
Note: the alerts/notifications and/or configuration commands could vary per device model but the concept is the same.
Remember the ping will be originated on B.3 so you must enable access for icmp on the firewall B.2. You could create an interface loopback to be the source, so your IP SLA should be:
ip sla 1
icmp-echo <B.1 interface IP facing to B.2> source loopback X
frequency 5
Hope it is useful
:-)
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide