BGP Multihoming 2 providers full or partial?

Sun May 31 13:12:44 UTC 2015

BGP traffic engineering is kind of like Soda Prefer. that folks have.... Some like Pepsi, some Like Coke, some don't care as long as it is Cold and fizzy.

Depending on who your two providers are, you may be happy with just taking full routes, and doing some creative routing (i.e. setting up static routes for outbound for specific prefixes, not the most elegant solution).

Remember, BGP allows for Asymmetric routing, as such with default routes, you will have traffic coming in from both providers (by default) and traffic going out via one of them (by default).

At the end of the day you are most likely to make a decision based on what is your cost for having a more powerful router, and how much 'creative routing' you want to / need to do.
(My Personal opinion, is that it is a 50/50 decision to upgrade hardware just to take full routing tables.. however if there are other reasons or needs, that can sway the decision in one direction or the other).

:) 

Faisal Imtiaz
Snappy Internet & Telecom

----- Original Message -----
> From: "Maqbool Hashim" <maqbool at madbull.info>
> To: "Joseph Jackson" <jjackson at aninetworks.net>, nanog at nanog.org
> Sent: Sunday, May 31, 2015 8:09:02 AM
> Subject: RE: BGP Multihoming 2 providers full or partial?
> 
> Hi,
> 
> No the current devices can't support full table (well not from both
> providers) we would need to upgrade.  Really in terms of cost saving just
> want to make sure to not get charged overages because we utilise too much of
> one link and not enough of another.  I don't think the shortest AS path will
> be of that much concern or noticeable for most destinations.
> 
> We do however have a set of remote sites which communicate over the Internet
> to our central sites where the transit providers are.  Just general Internet
> at the remote sites- but traffic from remote sites to central sites would be
> the most important.
> 
> I am just not sure of exactly how to define the "partial" routing table
> criteria to our two providers.  Should we just take routes for each provider
> and their peers and a default from both?
> 
> The main reason for not taking a full routing table is the cost/inconvenience
> of upgrading existing hardware.
> 
> Thanks
> 
> -----Original Message-----
> From: Joseph Jackson [mailto:jjackson at aninetworks.net]
> Sent: 31 May 2015 12:41
> To: Maqbool Hashim; nanog at nanog.org
> Subject: RE: BGP Multihoming 2 providers full or partial?
> 
> Can your devices support a full table?
> 
> You can load balance  outbound traffic easily with out doing a full table.
> THo that won't be the shortest AS path.  In regards to cost savings how
> were you thinking of doing so?  Does one provider charge more?  Just use the
> cheaper provider.
> 
> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Maqbool Hashim
> Sent: Friday, May 29, 2015 3:37 AM
> To: nanog at nanog.org
> Subject: BGP Multihoming 2 providers full or partial?
> 
> Hi,
> 
> 
> We are an enterprise that are eBGP multihoming to two ISPs. We wish to load
> balance in inbound and outbound traffic thereby using our capacity as
> efficiently as possible. My current feeling is that it would be crazy for us
> to take a full Internet routing table from either ISP. I have read this
> document from NANOG presentations:
> 
> 
> https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCoQFjAA&url=https%3A%2F%2Fwww.nanog.org%2Fmeetings%2Fnanog41%2Fpresentations%2FBGPMultihoming.pdf&ei=cyRnVb--FeWY7gbq4oHoAQ&usg=AFQjCNFsMx3NZ0Vn4bJ5zJpzFz3senbaqg&bvm=bv.93990622,d.ZGU
> 
> 
> The above document reenforces my opinion that we do not need full routing
> tables. However I was seeking some clarity as there are other documents
> which suggest taking a full routing table would be optimal. I "guess" it
> depends on our criteria and requirements for load balancing:
> 
> 
> - Just care about roughly balancing link utilisation
> 
> - Be nice to make some cost savings
> 
> 
> We have PI space and two Internet routers one for each ISP. Either of our
> links is sufficient to carry all our traffic, but we want to try and balance
> utilisation to remain within our commits if possible. I am thinking a
> "rough" approach for us would be:
> 
> 
> - Take partial (customer) routes from both providers
> 
> - Take defaults from both and pref one
> 
> 
> Maybe we can refine the above a bit more, any suggestions would be most
> welcome!
> 
> 
> Many Thanks
> 
> 