OSPF merging 2 areas into one

[avilt]

I have a office setup with 4 locations, each connected by two 100mbps links from two different ISP's as shown in the attached diagram.
ISP-1 links are in OSPF Area0 and ISP-2 links are in OSPF Area-1. At main office, L3 switch's are also in Area0 and firewall is not running

any routing protocol. Except for the Main office, HSRP is configured on the LAN side.
The links are pretty stable and I have pure data network without any voice applications. Initially we were using very low end routers but now

all replaced with higher model with good memory and I have been thinking of assigning all the routers in a single OSPF area. The current design does not provide complete redundancy as there are no OSPF virtual links configured anywhere.

Appreciate some feed back on my plan. All the routers should point to the firewall as Default Gateway.

[Alessio Andreoli]

Just rewrite the network statement of Area 1.

According with what you decsribed nothing else should be impacted. Of course do it during out of office hours!!

router ospf 1

network 1.1.1.0 0.0.0.3 area 1

!type instead

network 1.1.1.0 0.0.0.3 area 0

If you have any particular redistribution,  take a "snapshot" of what the configuration , adjacencies , interfaces status are before and after the migration and verify the differences.

If the ISPs route are simple static routes you should not have any issue.

Alessio