[quagga-users 14902] Re: Zebra / quagga with BGP combined with policy based routes.

Hi Tim,

Thanks for the reply . Is there perhaps some documentation you can
refer me to ? Perhaps I'm restarted but I've been googling all morning
without much success.

thanks again.
-steph


On Thu, Jan 11, 2018 at 3:48 PM, Tim Bray <[email protected]> wrote:
> Hi,
>
> Yes.  You can tell zebra which table to update (linux only), but the
> default is main.
>
>
> Tim
>
>
> On 11/01/18 11:45, Stephan Viljoen wrote:
>> am I correct to assume that Zebra falls under the routing table main ?
>>  In other words , if none of my lower priority tables isn't HIT it
>> will fall through to my main routing table ? And if this is the case ,
>> can I tell it to use a different routing table with a lower priority.
>>
>> 500:    from 10.0.243.0/24 lookup PEERING
>> 510:    from 10.0.243.0/24 lookup UPSTREAM2
>> 32766:  from all lookup main  (Seems my pre-fixes received via zebra
>> (bgp) falls under this table. )
>> 32767:  from all lookup default
>>
>> ip route show table main
>> 168.167.253.0/24 via 192.168.179.40 dev enp2s0f1.555  proto zebra
>> 168.167.254.0/24 via 192.168.179.40 dev enp2s0f1.555  proto zebra
>> 168.167.255.0/24 via 192.168.179.40 dev enp2s0f1.555  proto zebra
>>
>> On Thu, Jan 11, 2018 at 11:49 AM, Tim Bray <[email protected]> wrote:
>>> Hi,
>>>
>>>
>>> What IP space are using?  Is it provider independent space?  presuming PI.
>>>
>>> I would be tempted to lose the default gateway, and BGP to the first and
>>> second links.
>>>
>>> Then for 2, use a local preference in quagga BGP to send the outbound
>>> traffic this way.       Then add AS-prepend to avoid inbound traffic on
>>> this connection.
>>>
>>> You will need a higher local preference on 3, to avoid traffic going down 2.
>>>
>>> So 1.  unchanged except routes coming over BGP
>>>
>>> 2, routes will come on BGP but you will pick and choose what you send
>>> out this way.
>>>
>>> 3, peer, so should have fewer BGP hops.  And set a higher local preference.
>>>
>>>
>>> Actually, i'm not sure this will work or is the right way.  You might
>>> still need policy routes.   But a good way to think.
>>>
>>>
>>> The reason for doing it this way is that you get a better route.   If
>>> provider one loses some routes that provider 2 happens to still have,
>>> then stuff still works.
>>>
>>>
>>>
>>> On 11/01/18 09:30, Stephan Viljoen wrote:
>>>> Hi There,
>>>>
>>>> I'm fairly new to working with dynamic routing protocols and would
>>>> appreciate it if someone is willing to give me some advice with the
>>>> following scenario.
>>>>
>>>> I've configured an edge router with three wan connection on it.
>>>>
>>>> 1: The first link goes to my primary upstream provider which acts as
>>>> my default gw .. nothing special here.
>>>> 2: The second link goes to a secondary upstream provider where I'm
>>>> using policy based routes for only certain internal pre-fixes .
>>>> 3: The third link is where things gets interesting :) This is a local
>>>> peering connection with other service providers using BGP .. so I've
>>>> configured Zebra / quagga with BGP which works pretty good.
>>>>
>>>> So my question is , is it possible to give the routes received via BGP
>>>> priority over the policy based routes ? So for instance , if a
>>>> customer comes from an ip-prefix with a policy based route in place is
>>>> it possible to follow
>>>> the BGP route first before following the policy set for it ?  I did
>>>> find a cumbersome way around the problem but I'm pretty sure this is
>>>> an unnecessary step.  I ended up configuring a second based policy for
>>>> all those pre-fixes
>>>> with a lower priority for the BGP routes . So if a customer wants to
>>>> access content via the peering link it will try and route there first
>>>> following the lower priority route but this comes with it's own
>>>> problems like when a peering host is down
>>>> it's still going to try and follow the route configured via policy
>>>> based which kinda makes the whole idea behind using BGP useless.
>>>>
>>>> Small example.
>>>>
>>>> 500:    from 10.0.243.0/24 lookup PEERING    :  This I feel is
>>>> unnecessary and would like to configure the incoming BGP pre-fixes
>>>> with a higher priority so this route will get followed first instead
>>>> of creating a policy based route for each of the incoming pre-fixes
>>>> which renders the BGP setup useless.
>>>> ip route list table PEERING
>>>> 168.167.252.0/24 via 192.168.179.40 dev enp2s0f1.555
>>>> 168.167.253.0/24 via 192.168.179.40 dev enp2s0f1.555
>>>> 168.167.254.0/24 via 192.168.179.40 dev enp2s0f1.555
>>>> 168.167.255.0/24 via 192.168.179.40 dev enp2s0f1.555
>>>>
>>>> 510:    from 10.0.243.0/24 lookup UPSTREAM2
>>>> default via 41.191.x.x dev enp2s0f0.210   : Gateway to second upstream;
>>>>
>>>> I really hope I'm making some sense here.
>>>>
>>>> Thanks in advance,
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