OSFP design question

[cajuntank]

Not getting any hits in the Cisco router forum so I'll try it out here.
I will have some Cisco 2800 series routers connecting to AT&T through 3Mb MPLS circuits. I am assuming AT&T will be running BGP and I will need to setup OSPF internally for my HP switches and Sonicwall UTM appliances. I will have a cable connection going to the Sonicwall for failover should AT&T fail and VPN to each other for access, so I need OSPF running. My question is in design; since I will have multiple sites (several subnets at each site), should I setup multiple areas or just have one area?
Not very fluent in using OSPF so my thought process on this is shakey.I know whatever I do OSPF'wise, I'll have to get AT&T setup to where it will redistribute those OSPF routes through BGP.
Any help would be appreciated.

 

[burtsbees]

My thought would be to have an area for each office, and the office with the Sonicwall as area 0. Are your edge devices 2800's, or are those at the ISP?
Cisco TAC would answer your questions also, assuming you have SmartNet on the 2800's...have you considered emailing TAC with your questions?
I am not very well versed with OSPF, since I have not used it extensively myself...

Burt

 

[cajuntank]

Problem is that those 2800's will be deployed and managed soley by AT&T. I will be able to give them my internal networks for broadcast and have them do the redistribute OSPF, but everything internal to those 2800's are my baby.

 

[cajuntank]

Ok... here's what I have come up with; my internal connections of my switch will be in some arbitrary OSPF Area # and the ports that make connection to my outgoing off-net (MPLS and/or VPN) will be in Area 0. Mirroring this at all my sites (changing that arbitrary OSPF Area # respectively) and keeping the outgoing off-net ports in Area 0 should keep my routes broadcast to a minimum since the only routes that should be broadcast across either my MPLS or VPN will be for Area 0 only and not all of my internal LAN subnets at each site.
Would anyone like to offer anything else?

 

[brianinms]

OSPF is overkill to determine if the link is down. Merely use IP SLA to manipulate your routing table.

 

[cajuntank]

I don't think the HP L3 switches have that functionality, I might be wrong.

 

[volkspower]

brianinms -

Why do you say OSPF is overkill? Just curious.

 

[brianinms]

If you are merely trying to determine if a link is up or down then use IP SLA. Configuring OSPF and redistributing that into bgp and having to wait for it to reconverge after an outage is overkill for the issue.

 

[cajuntank]

If I'm reading this correctly from the Internet, IP SLA is a Cisco IOS function that is not a IEEE standard for anyone else. My only Cisco appliance will be the router connecting to my private WAN MPLS circuit. All of my switches will be HP and my firewall to my failover cable connection will be a Sonicwall. The common denomenator between all of the appliances is OSPF, so I don't think I can not get away from using it. Don't know if this helps any or not, but I am hoping to be on the MPLS network only for a short time and get converted over to Metro Ethernet (100Mb-1Gb) before the end of next year. So those Cisco routers will go bye bye once I switch over to MetroE. So I am designing for now and also the future with this euquipment.

 

[burtsbees]

brianinms---I don't think he ever mentioned troubleshooting anything or having any links down---he simply wants to redistribute bgp into ospf and vice-versa, and was wondering how to set up OSPF with different offices.
cajuntank---here's more info on IP SLA...I don't think it has anything to do with what you are asking, unless I am totally missing something brian has brought up...

(

http://www.cisco.com/application/pd...s6350/c2001/ccmigration_09186a0080789b77.pdf)

Just for your own info...

From what you plan, it looks good to me.

Burt

 

[brianinms]

My reasoning was I have multiple customers running MPLS with ATT and getting them to allow redistribution into the BGP table in your VRF isn't the easiest thing to do. In addition they Jack with your metrics and getting support isn't easy either.

That being said, I must have confused this topic with another post and thought Cajuntank was wanting to determine when the MPLS link failed. Sorry for the misunderstanding.

 

[cajuntank]

Well I do need to determine when the MPLS link or network is unavailable to failover to the Sonicwall's VPN connection through the Internet. If that private MPLS network is down, shouldn't the Cisco router also being in OSPF area 0 fail the route over to the Sonicwall that's also in Area 0?

 

[norteldude78]

so...each LAN will have 2 connections to the other LANs - 1 through MPLS, the other through your cable connection? OSPF will choose the preferred route based on lowest cost metric (the MPLS path). If this route goes down, OSPF will have a backup route. I don't see a problem. You can talk with ATT about the metrics that will be set, but it will be your responsibility to make sure MPLS is preferred by setting lower metrics for the cable connection.

 

[norteldude78]

i mean higher metrics for cable connection

 

[cajuntank]

This is a statewide roll-out for school districts in Mississippi (the MPLS network that is), so AT&T has been very accommodating thus far. We have a pretty good relationship so I don't foresee any issues with the redistribution.