06-18-2012 04:02 PM - edited 03-04-2019 04:43 PM
So I have 4 sites total, two with dual routers off of them.
We currently have a single ospf area (everyone belongs to area 0)
I would like to split each site into it's own area.
However admitidly my ospf knowledge is limited. This was much easier when it was RIP, the problem with RIP being I was unable to weight links. Let me use an example.
From our San Diego office to our Detroit office we have a VTI link.
The detroit office has 2 routers running HSRP between a cable link and t1 (the cable is primary). Both of these routers use a VTI into our single San Diego router. I used ip ospf cost to specify which link is to be used on the San Diego side.
Anyway. For area 0 which is our main site, the tunnel config looks like.
interface Tunnel0
description tunnel to AIS San Diego
ip address 172.28.42.2 255.255.255.0
ip ospf network broadcast
ip ospf mtu-ignore
tunnel source GigabitEthernet0
tunnel mode ipsec ipv4
tunnel destination 64.87.xxx
tunnel protection ipsec profile VTI
!
!
interface Tunnel1
description tunnel to detroit office
ip address 172.28.41.1 255.255.255.0
ip ospf network broadcast
ip ospf cost 100
ip ospf mtu-ignore
tunnel source GigabitEthernet0
tunnel mode ipsec ipv4
tunnel destination 69.14.xxxx
tunnel protection ipsec profile VTI
!
!
interface Tunnel2
description tunnel to Detroit Data Center
ip address 172.28.49.1 255.255.255.0
ip ospf network broadcast
ip ospf mtu-ignore
tunnel source GigabitEthernet0
tunnel mode ipsec ipv4
tunnel destination 199.16.xxxx
tunnel protection ipsec profile VTI
!
interface Tunnel3
description tunnel to Detroit t1 router
ip address 172.28.50.1 255.255.255.0
ip ospf network broadcast
ip ospf cost 200
ip ospf mtu-ignore
tunnel source GigabitEthernet0
tunnel mode ipsec ipv4
tunnel destination 204.232.xxxx
tunnel protection ipsec profile VTI
!
router ospf 42
log-adjacency-changes
passive-interface GigabitEthernet0
network 172.28.41.0 0.0.0.255 area 0
network 172.28.42.0 0.0.0.255 area 0
network 172.28.49.0 0.0.0.255 area 0
network 172.28.50.0 0.0.0.255 area 0
network 192.168.1.0 0.0.0.255 area 0
!
In this example if I want the Detroit Site to be area 1, then these links connecting San Diego to Detroit also have to be in area 1 ?
Does anyone have a guide or examples/a refernce they could point me to ?
With 4 sites and dual routers in some of them, it is getting confusing
Solved! Go to Solution.
06-21-2012 05:34 AM
Prefixes mean Networks, we also call a Network ID or a Subnet ID a prefix. ex: 172.28.x.x. when i say how many prefixes, i mean how many subnets or network destinations.
Physical Distance doesnt matter at all, as long as you links are good and there is not a lot of routing info to be exchanged.
keep using ONLY Area 0, with ospf network type broadcast, so you have a DR and BDR. then you can manipulate DR/BDR selection.
plz Rate if it helped,
Soroush.
06-18-2012 06:51 PM
Hi there,
With OSPF area's you have to do it according to ur network physical and logical design, which at this point i dont know about it, but i can give u a few guide lines.
* I suggest you make these WAN links a part of Area 1 rather than area 0 to have better performance.
* when you create multiple areas, area 0 would be ur core network, and every routing update has to go through Area 0.
this means, even if you have ur area 1 directly connected to area 2, still everything goes through Area 0.
so, all you area's MUST be connected to Area 0, physically or through Virtual links.
there is this good piece of reference u might find useful:
http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml
finally, try to keep it as simple as possible. 4 sites and dual routers don't need to have a complicated routing mechanism. to be honest, One OSPF Area (0) is more than enough to have this network up and running
plz Rate if it helped.
Soroush.
06-18-2012 08:24 PM
I've attached a basic diagram of our current network set up.
The links I am referring to are strictly private/VPN.
It works pretty well now, I haven't bothered to wireshark the links and see how much bandwidth is eaten up by LSA's but we don't have a performance issue at all.
Our main traffic center is the AIS San Diego Router, all of our infrastructure is housed there. Waveform is a DNS fail over location (we're not quite ready for BGP yet). I was hoping by using area's id move routing updates and work off the data center routers, as they need to route public connections more than anything.
We will be adding 2 more sites (Atlanta and one in Canada) and I am open to design suggestions as this is my first OSPF network.
Thanks again man!
06-19-2012 11:19 AM
Hey John
how many prefixes do you expect to be in ur routing table at the end? Because if your routing table is not that large, you dont need to keep them speparated by OSPF Areas.
once your network is converged by ospf, there wouldnt be a lot of LSA travelling through ur network, just a buncha hello packets n stuff, unless you have an unstable network.
How far your sites are located from eachother doesnt mean that you have to devide your network, its is how big an busy your routing process could get.
you have good links, private, with back ups. you r good to go... a single area, i'd suggest. if ur company did a merger with another Co, then keep their Net in another area or sth
cheerZ,
Soroush.
06-20-2012 11:15 AM
So the 172 networks are just for the tunnels, we don't use those for anything else.
In terms of prexix's ? I am not sure I understand that term
At the end of the day we have about 12 private networks linked together behind these routers.
The distance between San Diego and Detroit is fairly large, but we have high speed links between all sites (the slowest being 10m fiber)
06-21-2012 01:09 AM
hi John,
are you having any issues with current configuration?
if no, then i would very agree with Soroush, keep it simple, and for network like this im gonna use only area 0.
regards,
06-21-2012 05:34 AM
Prefixes mean Networks, we also call a Network ID or a Subnet ID a prefix. ex: 172.28.x.x. when i say how many prefixes, i mean how many subnets or network destinations.
Physical Distance doesnt matter at all, as long as you links are good and there is not a lot of routing info to be exchanged.
keep using ONLY Area 0, with ospf network type broadcast, so you have a DR and BDR. then you can manipulate DR/BDR selection.
plz Rate if it helped,
Soroush.
06-22-2012 09:38 AM
I appreciate all the help guys, I am going to leave everything in Area 0 after reading ya'll's comments.
To answer a previous questions, we don't have any problems with the current setup. We do seem to have one tunnel that flaps more than it should (while all the others are rock solid), but I think thats a seperate issue.
Cheers, thanks for all the help!
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