[c-nsp] BGP transit selection from source customer network

[Alexandre Durand]

Hi Andrew,

Tnhan you for you answer. Actually youa re right about the inbound 
traffic in which I can easily advetise this network with a preference to 
my "ISPA", this is fine and already done.

The issue here is about the oubound traffic, when my customer traffic is 
going back out to ISP, I can also you weight on the router where I host 
this "ISPA" and use no-advertise attribute so I don t advertise
prefixes to others iBGP routers, fine but others customer traffic will 
also be routed via ISPA because the shortest ISP path is going throught 
this router too...

On the diagram below cust 1, cust2 from RO4 are routed through RO1 and 
then to ISPA, I just want cust1 to be routed over ISPA and cust2 over 
ISPb without using IGP metric.

ISPA....RO1----RO2.....ISPX
             I   \     /  |
             I     \  /   |
             I      /\    |
           RO3    RO4
                       | | |
                   cust1 cust2 ...

hopes this diagram helps

regards

Alexandre



On 01/08/11 15:57, Andrii Morozov wrote:
> Hello Alexandre,
>
> If my understanding of what you've written is correct, there is no 
> need for implementing a VRF in your case.
>
> As far as I understood, you want the downstream traffic for a specific 
> address block to be routed via particular ISP, right?
> For this purpose you should create a route object in RIPE database (if 
> it's no created yet) and start to announce this block normally to 
> desirable ISP and at the same time advertise it with AS_PATH prepend = 
> X (for example, X=5) to those ISPs, which you don't want the traffic 
> to pass through.
> This is achieved via creating an outbound route policy (route-map in 
> case of Cisco) towards your ISPs.
>
> After you accomplish the route policy implementation, you can check 
> the result via looking glass of some other's ISP to see how your block 
> "is seen" frow the world.
>
> Best wishes, Andrew.
>
> 2011/8/1 Alexandre Durand <alexandre.durand at tasfrance.com 
> <mailto:alexandre.durand at tasfrance.com>>
>
>     Hi,
>
>     I was wondering if any of you had alerady the experience of source
>     routing tarffic over multihomed network based?
>
>     We run a network with several ISP and peering that provide
>     internet full routing table and we want for specific network bloc
>     to be routed through one of our dedicate cheap transit ISP, but
>     leave others on the same router to be routed via others ISPs. we
>     run full meshed IBGP and multi-home transits or peering.
>
>     I might have found 2 solutions and use PBR or VRF but I don t know
>     how to implement them yet. VRF looks nice but I may miss transit
>     redundancy. Let s say I create a specific vrf for this ISP, others
>     ISPs remain in the global routing table, if this provider is not
>     availaible, the traffic is no longer routed out the others ISPs
>     and also I can t share and send traffic over peerings...
>
>     Is there any doc or guide for such solution that I can use so I
>     can work on the appropriate solution and configuration and adapt
>     it to our needs and network specifications?
>
>     -- 
>     Alexandre DURAND
>     TAS FRANCE
>     WTC 1-K, 1300 route des Crêtes
>     06560 Valbonne Sophia Antipolis
>     Phone :    +33 (0)4 92 94 56 93
>     Fax   :    +33 (0)4 92 94 33 99
>     Web: http://www.tasfrance.com
>     Email : alexandre.durand at tasfrance.com
>     <mailto:alexandre.durand at tasfrance.com>
>     peering: http://as8554.peeringdb.com
>
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>


-- 
Alexandre DURAND
TAS FRANCE
WTC 1-K, 1300 route des Crêtes
06560 Valbonne Sophia Antipolis
Phone :    +33 (0)4 92 94 56 93
Fax   :    +33 (0)4 92 94 33 99
Web:       http://www.tasfrance.com
Email :    alexandre.durand at tasfrance.com
peering:   http://as8554.peeringdb.com