[j-nsp] Dealing with multihomed customer BGP primary/backup links

[Alan Gravett]

Hi Cydon,

MC-LAG will provide the functionality you are looking for using
active/standby mode.
The active/standby mode is also available on both DPC and MPC hardware.

Alan


On Thu, Jul 14, 2016 at 1:43 AM, Cydon Satyr <cydonsatyr at gmail.com> wrote:

> uRPF check doesn't work since customer can just advertise his routes over
> backup link.
> I had some hopes for conditional bgp advertisement and SCU/DCU but I don't
> think it works not to mention it's like trying to kill a bee with a hammer.
>
> What about MC-LAG between two routers and just setting one link as backup
> one as primary...or something?
> It has to be something which doesn't require any change on customer side.
>
> Thanks
>
> Regards
>
> On Wed, Jul 13, 2016 at 11:33 PM, Mark Tinka <mark.tinka at seacom.mu> wrote:
>
> >
> >
> > On 13/Jul/16 22:23, Clinton Work wrote:
> >
> > > On the primary BGP session I would set Local-pref 150 and send MED 100
> > > for example.
> > > On the backup BGP session, set local-pref 100 and send MED 150.
> > >
> > > The local-pref will set the preferred route in your network to use the
> > > primary BGP session.   The MED should influence the customer to use the
> > > primary link as their preferred route as well.  Savvy customers can
> > > easily override the MED value, but it should work for the majority of
> > > the customers.
> >
> > Savvy customers can just de-aggregate and override LOCAL_PREF values.
> >
> > Also, assuming the customer resets MED, LOCAL_PREF only provides control
> > in one direction. Nothing stops the customer from statically routing
> > traffic over a specific path (or both paths simultaneously) for outbound
> > traffic.
> >
> > Mark.
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