Re: Exploring EVPL / NNI redundancy options

["Eric C. Miller via NANOG" <nanog () lists nanog org>]

We use the E-LAN service as an additional connectivity. I've had to too many "Any to only somewheres" for it be the 
only circuit at a site. ELAN is more cost effective because it's a single port billing (2Gbps at this site, 10Gbps at 
this other site) and your traffic can go anywhere. I always build P2P VLANs overtop the ELAN because frame relay and 
P2MP OSPF gave me ptsd.

With the EVPL NNI/E-UNI, there's usually a dual cost billing model - The cost of the E-UNI port at the Site (1G/10G, 
etc) + the cost of the EVC to the NNI port at the datacenter. So the 2nd EVC will be a cost increase, but it should be 
heavily discounted compared to the cost of the first EVC.

Billing for NNIs is where the negotiations really are. We usually get no-cost NNIs once we have a couple of UNIs, 
regardless of the UNI bandwidth, but you have to have several UNIs on one contract so they have something to show for 
it. Ports in the field are where the true costs for the provider are. Pay your own cross connect fees to help the 
conversation along as well.

Eric
________________________________
From: Mark Blackford <mblackf () gmail com>
Sent: Friday, January 16, 2026 9:42 AM
To: North American Network Operators Group <nanog () lists nanog org>
Cc: Eric C. Miller <eric () ericheather com>
Subject: Re: Exploring EVPL / NNI redundancy options

Thanks for the response Eric.  I'm glad you touched on the E-LAN type services because I thought that a multi-point 
option over L2VPN could be an offer.  It seems the VLAN PtP options give me more control on traffic engineering.

For the PtP, "two VLAN" scenario that you spelled out, is that treated as two distinct circuits at twice the cost of 
one circuit or do you ever have carriers discount that a bit?  I expect to pay "something" for the redundancy, but I 
don't need twice the bandwidth on the "Enhanced" NNI to the site.

I also wonder if the site bandwidth would count towards the utilization commitment required on the tail NNIs.Do you 
know how that is treated?

Thanks again!
Mark



On Fri, Jan 16, 2026 at 7:43 AM Eric C. Miller <eric () ericheather com<mailto:eric () ericheather com>> wrote:
Every carrier calls it something different, but it boils down to a VLAN on the carrier's port that takes you PtP to 
another site. For example:

Dallas datacenter has a NNI with Provider. On that NNI, you've been given VLAN 101 that PtPs to Site.
Atlanta datacenter has a NNI with Provider. On that NNI, you've been given VLAN 201 that PtPs to Site.

Site has an "Enhanced" UNI where Provider has given you 2 VLANs. VLAN 101 is PtP to Dallas, VLAN 201 is PtP to Atlanta.

Some MEF-head will surely correct the terminology here, but having worked with just about every national carrier, they 
all use the terms in different ways.

...Or, you can buy an E-LAN type service that is any-to-any and then do your own network over top of it. Most problems 
I've had with E-LANs revolve around spanning-tree (make sure your edge devices aren't sending BPDUs into the E-LAN) or 
the provider VPLS locking up where certain endpoints can't be seen from other endpoints. Be prepared to recover your 
network using hairpin routing from a couple of sites while the provider resets everything.

Eric
________________________________
From: Mark Blackford via NANOG <nanog () lists nanog org<mailto:nanog () lists nanog org>>
Sent: Friday, January 16, 2026 8:33 AM
To: North American Network Operators Group <nanog () lists nanog org<mailto:nanog () lists nanog org>>
Cc: Mark Blackford <mblackf () gmail com<mailto:mblackf () gmail com>>
Subject: Exploring EVPL / NNI redundancy options

Does anyone have experience implementing redundancy on their EVPL services
within the same carrier?  For instance, I have many point-to-point
scenarios using EVPL providers to connect sites to Dallas. I’m looking to
add a new pop in Atlanta this year for expansion and redundancy.

It seems possible to have a “Site A” with a current drop off NNI in Dallas
added to the new POP on Atlanta within the same carrier network for data
center redundancy, but I am not sure how practical that is in terms of cost
and implementation. Latency would vary of course, and I am assuming they
give you a different VLAN (but maybe not?).

I welcome any comments like if this is a good idea or not, what carriers I
should consider, and experience with cost.

Thanks in advance!

Mark Blackford
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