Re: BGP prefix filter list

[Blake Hudson <blake () ispn net>]

Ca, taking a self-originated default route (with or without an 
additional partial view of the global routing table) from your transit 
provider's edge router seems to make the assumption that your transit 
provider's edge router either has a full table or a working default 
route itself. In the case of transit provider outages (planned or 
unplanned), the transit provider's edge router that you peer with may be 
up and reachable (and generating a default route to your routers), but 
may not have connectivity to the greater internet. Put another way, if 
your own routers don't have a full routing table then they don't have 
enough information to make intelligent routing decisions and are 
offloading that responsibility onto the transit provider. IMHO, what's 
the point of being multi-homed if you can't make intelligent routing 
decisions and provide routing redundancy in the case of a transit 
provider outage?



Mike Hammett wrote on 5/15/2019 2:19 PM:
> As an eyeball network myself, you'll probably want to look at those 
> things. You don't need to run a CDN to know where your bits are going.
>
>
>
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
>
> Midwest-IX
> http://www.midwest-ix.com
>
> ------------------------------------------------------------------------
> *From: *"Ca By" <cb.list6 () gmail com>
> *To: *"Mike Hammett" <nanog () ics-il net>
> *Cc: *"Dan White" <dwhite () olp net>, nanog () nanog org
> *Sent: *Wednesday, May 15, 2019 2:14:21 PM
> *Subject: *Re: BGP prefix filter list
>
>
>
> On Wed, May 15, 2019 at 11:52 AM Mike Hammett <nanog () ics-il net 
> <mailto:nanog () ics-il net>> wrote:
>
>     You can't do uRPF if you're not taking full routes.
>
>
> I would never do uRPF , i am not a transit shop, so no problem there. 
> BCP38 is as sexy as i get.
>
>
>     You also have a more limited set of information for analytics if
>     you don't have full routes.
>
>
> Yep, i don’t run a sophisticate internet  CDN either. Just pumping 
> packets from eyeballs to clouds and back, mostly.
>
>
>
>     -----
>     Mike Hammett
>     Intelligent Computing Solutions
>     http://www.ics-il.com
>
>     Midwest-IX
>     http://www.midwest-ix.com
>
>     ------------------------------------------------------------------------
>     *From: *"Ca By" <cb.list6 () gmail com <mailto:cb.list6 () gmail com>>
>     *To: *"Dan White" <dwhite () olp net <mailto:dwhite () olp net>>
>     *Cc: *nanog () nanog org <mailto:nanog () nanog org>
>     *Sent: *Wednesday, May 15, 2019 1:50:41 PM
>
>     *Subject: *Re: BGP prefix filter list
>
>
>
>     On Wed, May 15, 2019 at 7:27 AM Dan White <dwhite () olp net
>     <mailto:dwhite () olp net>> wrote:
>
>         On 05/15/19 13:58 +0000, Phil Lavin wrote:
>         >> We're an eyeball network. We accept default routes from our
>         transit
>         >> providers so in theory there should be no impact on
>         reachability.
>         >>
>         >> I'm pretty concerned about things that I don't know due to
>         inefficient
>         >> routing, e.g. customers hitting a public anycast DNS server
>         in the wrong
>         >> location resulting in Geolocation issues.
>         >
>         >Ah! Understood. The default route(s) was the bit I missed.
>         Makes a lot of
>         >sense if you can't justify buying new routers.
>         >
>         >Have you seen issues with Anycast routing thus far? One would
>         assume that
>         >routing would still be fairly efficient unless you're picking
>         up transit
>         >from non-local providers over extended L2 links.
>
>         We've had no issues so far but this was a recent change. There
>         was no
>         noticeable change to outbound traffic levels.
>
>
>     +1, there is no issue with this approach.
>
>     i have been taking “provider routes” + default for a long time,
>     works great.
>
>     This makes sure you use each provider’s “customer cone” and SLA to
>     the max while reducing your route load / churn.
>
>     IMHO, you should only take full routes if your core business is
>     providing full bgp feeds to downstrean transit customers.
>
>
>         -- 
>         Dan White
>         BTC Broadband
>         Network Admin Lead
>         Ph  918.366.0248 (direct)   main: (918)366-8000
>         Fax 918.366.6610            email: dwhite () mybtc com
>         <mailto:dwhite () mybtc com>
>         http://www.btcbroadband.com