Well here, we tell them that we are happy to do this as long as their
other ISP is willing to work with us to advertise the same /24, and
they get their own AS-number and they upgrade their equipment to nice
Cisco gear that talks BGP and that we understand and can support.
Depending on whether or not they want load-sharing or just backup,
they need either a low-end IOS-capable router or something studly
enough to handle full routes.
If the customer decides that they're really not ready to multi-home on
that basis, then what we offer is multi-homing to two of our pops or
via two different services, so that it's strictly an internal problem
on our side. Typically we'll back up a point-to-point circuit with a
frame-relay or even DSL, the key being that the primary service has to
give a clear "line down" indication. We've had some customers that
want to back up a DSL connection with a 56K leased line, and their
DSL router only speaks RIP and ATM/DSL sub-interfaces don't give a
useful PVC down indication.
Maybe we're strange, but we'll only talk BGP to our customers, while
other ISP's will only talk RIP, EIGRP or OSPF. From our perspective
BGP is easily and explicitly controllable, while the IGP's can easily
do things that you really didn't intend.
George
> From cisco-nsp-request@puck.nether.net Tue Aug 8 10:45:23 2000
> Resent-Date: Tue, 8 Aug 2000 10:47:03 -0400
> Received-Date: Tue, 8 Aug 2000 10:25:21 -0400
> Date: Tue, 8 Aug 2000 22:25:11 +0800 (SST)
> From: Jason Lim <jas@staff.singnet.com.sg>
> X-Sender: jas@singapura.singnet.com.sg
> To: cisco-nsp@puck.nether.net
> Subject: [nsp] dual-homed issue
> Resent-From: cisco-nsp@puck.nether.net
> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/3355
> X-Loop: cisco-nsp@puck.nether.net
> Precedence: list
> Resent-Sender: cisco-nsp-request@puck.nether.net
>
> Hi all,
>
> Actually, I need advise in dual-homing policy with our lease line
> customers. We have encountered some issues on lease lines customers
> wanting to dual-home their connection with our ISP(ISP1) and other
> ISP(ISP2) and this demand is growing. For example, a customer with two
> connection to ISP1(AS100) and ISP2(AS200) would be getting 203.222.100/24
> from ISP1 and 155.169.22/24 from ISP2. Customers wants redundency by
> asking ISP1 to advertise 155.69.22/24 and ISP2 to advertise
> 203.127.100/24 as well.
>
> The reasons why it's an issue because
>
> 1) These customers are not running BGP. I understand that conditional
> advertisment with BGP can solve the problem.
> 2) These customers wants ISP1 to advertise IPA blk which belong to
> other ISP2 and likewise for ISP2 to advertise ISP's IPA
>
> Well, currently there is now no mutual agreement with other ISPs to do so.
>
> I would like to know :
> 1) How will like to know how will it impact ISP1 and ISP2 in term of
> routing advertisment,tables,etc ?
> 2) Will ISP1 and ISP2 have problems of routing holes for advertising
> routes belonging to other ISPs' ASes.
>
> I am not sure if there are any other technical implication.
> How does other ISPs in US or other parts of the world
> dual-homed their customers' who do not run BGP(only statics route)?
> What are the pros/cons of doing/not doing this ??
>
> Thank you very much
> Regards
> Jason
> SingNet NOC
> Network Engineer
>
>
>
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