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OER on border with default routes

Overview: We have 4 external routers each has two connections to multiple ISPs using BGP4. As our traffic is mostly outbound, we used static routes to load share/balance both circuits on each router. The IGP used is OSPF.

Problem: Recently, we are experiencing network brownouts due to peering issues of our ISPs. This results to downgraded service and our customers are complaining about the slowness of our network.

Possible solution: I remember Cisco supports OER (optimized edge routing) on its IOS 12.3(8t) and later; to monitor network performance based on latency, packet drops, etc.. However, I'm not sure if that's only applicable to BGP enabled routes or it can be applied to my scenario, where I'm ignoring BGP learned paths using default static routes (

Is there someone on this forum who could help me out or clarify this thing further? I can probably build a lab with 6 core routers (fully meshed) and 2 edge routers to run OER, but I don't want to do it if my efforts will be put into waste (or simply if my application or setup is not going to be supported).

I appreciate anyone's inputs.



Re: OER on border with default routes

OER should be able to help you with path selection based on response time, packet loss, traffic load, path availability, cost minimization.

it is not limited to BGP only environments.

OER is best used in multi Internet link or multi WAN connections with multiple routes to the destination.

OER supports BGP static route configurations.

the OER master controller can belong in a iBGP and/or OSPF or EIGRP environment.

please see the following link for more OER info:


Re: OER on border with default routes

Did you get this to work?

I have a Master/Border#1 and Border#2

Both are receiving Def Routes via BGP4 from 2 diff ISP.

Border2 is primary in/out internet traffic with local pref for outbound while Border1 is using AS-Prepend to force traffic inbound to Border2.

My Master and Borders go active but I do not see any prefixes. I have "max-path ibgp 2" configured on both routers:

R1 (Master and Border)

Network Next Hop Metric LocPrf Weight Path

*>i0.0.0.0 0 200 0 8560 i

* 100 0 19860 i


Network Next Hop Metric LocPrf Weight Path

* i0.0.0.0 0 100 0 i

*> 0 200 0 8560 i

Super Bronze

Re: OER on border with default routes

No, OER doesn't require BGP (even the prior to PIRO versions).

With default routes, what you do is have OER inject statics. However, it will only inject statics on individual boarder routers, so you need to redistribute them to the other border routers.

I have one pair of Internet connected routers running in such a configuration. I use OSPF, with a OSPF process unique to OER, to communicate the injected statics between the routers. (I also use OER with BGP [other configs], With BGP though, you can communicate the route changes within BGP.)

BTW, you might want to review the Cisco papers and examples using OER, since some of the configuration defaults are a bit slow to respond.


Re: OER on border with default routes

A little confuse here. I don't think I need statics or ospf. According to

eBGP sessions provide OER Parent routes, their existence in the IP routing table, along with IP CEF, NetFlow...iBGP peers, and then potentially injected into the IP routing table of these peers

Despite my Master and Borders are active, "show oer" for prefix are blank

A 2nd question - do you know of any good monitoring that would alert me if OER changes routes so i know when brown-outs are occuring.


Super Bronze

Re: OER on border with default routes

re: 2nd question

There's a 3rd party product (vendor's name doesn't come to mine) that can monitor PfR. (PfR supports an info API that OER doesn't.)

You can also have OER log changes to a syslog server and have a script monitor those.

My suggestion for statics was because you noted you were using default routes. If you're running eBGP, OER can inject BGP route changes.

My suggestion for OSPF (or another IGP) is if statics are being used, you need a method to communicate route changes between BRs.

As far as show OER prefixes being blank, there is some delay while OER learns traffic (this also assumes you've enable learning). More delay before OER injects routes.

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