Re: [c-nsp] /18 and multihomed BGP

2010-08-13 Thread RAZAFINDRATSIFA Rivo Tahina
Thanks Adam, in fact, I'm already with 2 upstreams, each one with 2 links, I do load balancing with them, announcing a /24 from one link to another according to the traffic, these 2 existing ISPs have /24 filters. I'm adding a new ISP with 3 links, and this 3rd ISP wants to change a unique

Re: [c-nsp] /18 and multihomed BGP

2010-08-13 Thread Gert Doering
Hi, On Fri, Aug 13, 2010 at 03:02:46PM +0300, RAZAFINDRATSIFA Rivo Tahina wrote: in fact, I'm already with 2 upstreams, each one with 2 links, I do load balancing with them, announcing a /24 from one link to another according to the traffic, these 2 existing ISPs have /24 filters. I'm

Re: [c-nsp] /18 and multihomed BGP

2010-08-13 Thread Heath Jones
Robert's response pretty much covers it all really. If those 2 ISP's are advertising /24's out to the wider internet, your screwed. Traffic will never come down via this new ISP. The way to solve it, is to advertise the /24's as you already are, but get those 2 ISP's to summarize into a /18

Re: [c-nsp] /18 and multihomed BGP

2010-08-13 Thread Adam Armstrong
On 13/08/2010 17:00, Heath Jones wrote: Robert's response pretty much covers it all really. If those 2 ISP's are advertising /24's out to the wider internet, your screwed. Traffic will never come down via this new ISP. The way to solve it, is to advertise the /24's as you already are, but get

Re: [c-nsp] /18 and multihomed BGP

2010-08-13 Thread Heath Jones
I mentioned that also... On 13 August 2010 17:51, Adam Armstrong li...@memetic.org wrote: On 13/08/2010 17:00, Heath Jones wrote: Robert's response pretty much covers it all really. If those 2 ISP's are advertising /24's out to the wider internet, your screwed. Traffic will never come down

Re: [c-nsp] /18 and multihomed BGP

2010-08-12 Thread Adam Armstrong
On 12/08/2010 13:21, RAZAFINDRATSIFA Rivo Tahina wrote: Hi all, I'm BGP multihomed with 2 ISPs and have a /18 subnet. I declared the /18 block in RIPE database as 64 /24. I'm adding a new ISP and he asked me to modify the 64 /24 in RIPE to a unique /18. How does this change affect the existing

Re: [c-nsp] /18 and multihomed BGP

2010-08-12 Thread Heath Jones
Hi If you advertise the /18 to one ISP (a) and the /24 to another ISP (b), you will find that all your traffic will enter via the 2nd ISP (b) as it will be the more specific routes in global BGP tables. Is there a reason you wanted to use 64x /24's in the first place? Cheers Heath On 12

Re: [c-nsp] /18 and multihomed BGP

2010-08-12 Thread Robert Lister
On Thu, 2010-08-12 at 15:21 +0300, RAZAFINDRATSIFA Rivo Tahina wrote: Hi all, I'm BGP multihomed with 2 ISPs and have a /18 subnet. I declared the /18 block in RIPE database as 64 /24. I'm adding a new ISP and he asked me to modify the 64 /24 in RIPE to a unique /18. The RIPE database is