<html><head></head><body bgcolor="#FFFFFF"><div>The easier way is using BGP PfR to do this.</div><div><br></div><div>Without using PfR and smaller routers in the past I've used route servers (running quagga or similar) having the routers as RR clients to the route server and letting scripts on the RS handle the policy side of things. </div>
<div><br></div><div>As for memory usage, here be dragons!</div><div>If you run two full feeds into a VRF instead of global table you're looking at over 4GB of RAM.<br><br><div>Sent from my iPhone. </div></div><div><br>
On 26/04/2012, at 16:12, "Sean K. Finn" <<a href="mailto:sean.finn@ozservers.com.au">sean.finn@ozservers.com.au</a>> wrote:<br><br></div><div></div><div><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
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--></style><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Are you Inbound-Heavy or Outbound-Heavy?</span></p><p class="MsoNormal">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">For Inbound-Heavy..</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I’ve seen it done where you run something monitoring what your link to trigger when you consider it ‘full’, such as Cacti with THRESHOLD module with alerting turned on, or otherwise a timed event trigger to run, at, lets say, 30 minutes before you regularly hit peak time.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">e.g. a cron-job on a linux box somewhere, or a triggered script, SSHing / (Or Telnetting) into a server, running an ‘expect’ script, and then running the commands that will either ‘turn on’ bgp, or change your route maps.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The real fun will be in HOW you balance your traffic across these links.</span></p><p class="MsoNormal">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I would be of a mind to run both as active-active, and to use route-maps in all of their glory and configuration hell to try to balance your traffic as best as possible.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If you have multiple /24’s you could preference some over one, and others over the other, and shuffle them around until you approximate some sort of balance,</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Or,</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">On your least-preferential route, add an AS path prepend or two to make it look like a longer path, and somehow achieve some sort of lucky balance.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Adding a second carrier is really where the fun begins, and, being the wild internet, you really just have to come up with a configuration or two, deploy, and suck-it-and-see.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">For outbound-heavy traffic, you should start by profiling which AS’s you send the most amount of traffic to, then, figure out which ones are ‘closest’ on the network to each of your two connections.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If your routers are big enough, you could take two default-routes via BGP from both providers, AND two full-global or full-national routing tables.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Be careful with taking too many routes, if your routers don’t have enough ram to hold it all BGP will die and you’ll just stop routing, period.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If you can take two full global tables, I’d suggest at least 2GB of ram (Others on the list feel free to chip in at this point what’s enough ram), then you can construct some route-maps to tag certain prefixes learnt from certain networks with local-preferences, to push traffic out an appropriate link.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">In essence though, even if you turn on your second link when your first one is maxing out, you’re still going to need route maps, one way or another, to control which of your BGP neighbors see’s what.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Welcome to BGP Hell </span><span style="font-size:11.0pt;font-family:Wingdings;color:#1f497d">J</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">(Otherwise known as Job Security).</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">S.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:ausnog-bounces@lists.ausnog.net">ausnog-bounces@lists.ausnog.net</a> [mailto:<a href="mailto:ausnog-bounces@lists.ausnog.net">ausnog-bounces@lists.ausnog.net</a>] <b>On Behalf Of </b>James Mcintosh<br>
<b>Sent:</b> Thursday, April 26, 2012 3:47 PM<br><b>To:</b> <a href="mailto:ausnog@lists.ausnog.net">ausnog@lists.ausnog.net</a><br><b>Subject:</b> [AusNOG] Multiple IP Transit BGP</span></p></div></div><p class="MsoNormal">
</p><div><div><p class="MsoNormal" style="background:white"><span style="color:black">Hi Noggers,</span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white">
<span style="color:black">We currently advertise our whole IP range via a single IP Transit upstream carrier who supplies us 150Mbps of transit.</span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black">We are are adding another 70Mbps but from a different carrier.</span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black">I've Googled high and low but can't seem to find the answer and I'm personally a bit rusty on my BGP. Really hoping some of the pro's on the list can help.</span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black">How would we advertise make use of the the new 70Mbps IP transit but only once the existing 150Mbps was full. As an overflow type of set up.</span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black">Is this even possible? Or are there better ways to manage multiple upstream carriers?</span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black">I'm using a Cisco 7206 VXR.</span></p></div>
<div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black">Thanks and really appreciate the help...</span></p>
</div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white"><span style="color:black"> </span></p></div><div><p class="MsoNormal" style="background:white">
<span style="color:black">-James</span></p></div></div></div></div><div><span>_______________________________________________</span><br><span>AusNOG mailing list</span><br><span><a href="mailto:AusNOG@lists.ausnog.net">AusNOG@lists.ausnog.net</a></span><br>
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