06-07-2009 10:07 PM - edited 03-04-2019 05:01 AM
hi experts,
i have a 6509 and a 3750 connected via FSO (free space optics). i will be adding a fiber connection on both swithces. both FSO and fiber have L3 IP address configured. how can i route properly, avoiding loops, between these devices? i'm considering a floating static route for this one. below is the config for the FSO connection, VLAN 250
6509E-MAIN
vlan 250
name 172.25.250.2/31
interface Vlan250
ip address 172.25.250.2 255.255.255.254
no ip proxy-arp
ip flow ingress
ip pim dense-mode
interface GigabitEthernet7/3
description to 3750G-TEMP g1/0/28
ip address 172.25.250.38 255.255.255.254
no ip proxy-arp
ip flow ingress
ip pim dense-mode
speed nonegotiate
mls qos trust dscp
router ospf 10
no passive-interface GigabitEthernet7/3
network 172.25.250.2 0.0.0.0 area 4949
network 172.25.250.38 0.0.0.0 area 4949
______________________
3750G-TEMP
interface GigabitEthernet1/0/28
description to 6509E-MAIN G7/3
no switchport
ip address 172.25.250.39 255.255.255.254
no ip proxy-arp
ip pim dense-mode
speed nonegotiate
mls qos trust dscp
router ospf 10
no passive-interface GigabitEthernet1/0/28
network 172.25.250.39 0.0.0.0 area 4949
06-07-2009 11:14 PM
You don't need any floating static.
Regular OSPF is enough for load balancing (optional) and loop avoidance.
06-08-2009 12:05 AM
thanks for giving me a hint paolo! i'll now use the ip ospf cost between the two and make the fiber's costs lower to make it the preferred route. can someone verify my config below:
interface GigabitEthernet7/3
description This is the FSO link
ip address 172.25.250.38 255.255.255.254
ip ospf cost 2
no ip proxy-arp
ip flow ingress
ip pim dense-mode
speed nonegotiate
mls qos trust dscp
interface GigabitEthernet7/4
description This is the FIBER link
ip address 172.25.250.x 255.255.255.254
ip ospf cost 1
no ip proxy-arp
ip flow ingress
ip pim dense-mode
speed nonegotiate
mls qos trust dscp
router ospf 10
network 172.25.250.x 0.0.0.0 area 4949
06-08-2009 04:29 AM
When defineing OSPF, you could add "passive-interface default", unless this is a standard setting on your IOS build.
06-08-2009 01:44 PM
OP doesn't need passive interface, instead he just need a way to prefer paths. This is done by setting the ospf cost as indicated above.
06-08-2009 07:27 PM
do i need to issue the 'clear ip ospf process' command after configuring the interfaces with 'ip ospf cost' command?
06-08-2009 10:56 PM
No, but please remember to rate useful posts with the scrollbox below.
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