will ISP peer with 2 local WAN routers?

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1

Hi guys,

I have a customer who peers via eBGP with Lightpath aka Cablevision (AS
6128) and Level3 (AS 3356) and wants to do some dual-WAN router redundancy.

I have heard that carriers will sometimes agree to set up a /29 WAN subnet
for a customer and peer with (2) customer routers.

The customer is delaying on providing me with the proper circuit ID &
contact information to be able to call Lightpath and Level3 directly and
find out if they will do this, so I thought of asking this list.

Is anyone aware if Lightpath and Level3 will agree to something like this?

Thanks,

Adam

2

The gotcha with that is then you need a switch in front of the routers. I'd just setup a carrier on each router and run ibgp between.

3

Time Warner installed a Juniper EX4200 as the CPE device for us, so we connected 2 routers and had two separate BGP sessions. They have us a /29 to accomplish it.

-Randy

4

Thanks, Justin. Yes, we considered that option, too. But then if one WAN
router goes down, the customer will only have connectivity through a single
upstream provider. We'd prefer to maintain connectivity to both even if a
router fails. Switches in front of the routers is no problem.

5

But the switches themselves are a single point of failure, so if a switch dies you still only have a single provider (assuming one switch per provider). :wink:

All you're doing is moving the your single point of failure from the routers to the switches, with arguably very little increase in actual reliability (if any, depending on whether you think switches are less likely to fail than routers).

- Pete

6

Pete,

Good point, thanks. Yes, in this case, there is some cause to believe that
the switches will prove more reliable than the routers. They're older
7200VXR's and have had some lockups in the past, possibly due to PA card /
IOS incompatibilities.

But you're right, we are also considering accepting full or partial routes
from both providers, one provider per router, and then doing iBGP between
them to balance the load. We're thinking of deploying default routes and
HSRP to stacked 3750's for round-robin load balancing on the LAN side.

Thanks for the help!

Adam

7

A bit late to the discussion, but we use a stack of EX switches which
terminate L2 connections from the providers and two routers which have BGP
sessions with them.
Each switch has ports provisioned so that in case one switch fails, we just
simply move the ethernet cable to the working switch and everything is fine.

Eugeniu

8

Adam Greene wrote:

Hi guys,

I have a customer who peers via eBGP with Lightpath aka Cablevision (AS
6128) and Level3 (AS 3356) and wants to do some dual-WAN router redundancy.

I am not optimistic for your odds in having 6128 do anything other than /30 for you.

(Though even then you still have options, up to and including eem IP takeover)

I have heard that carriers will sometimes agree to set up a /29 WAN subnet
for a customer and peer with (2) customer routers.

Carriers who do that and more are my favorites.

9

Offer to provide a /29 out of your own arin assigned block works wonders