<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0cm;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.yiv736869550tab
{mso-style-name:yiv736869550tab;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-AU link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Along with RR’s, would be the option of using confederation, private AS’s or a combination of all three (if some major Pop’s on the network can see advantages of either using confederation or private AS numbers over just using RR’s across the entire network to separate out the local IGP (e.g. OSPF) domains & can then use RR’s within those as well if full-mesh isn’t desired or practical). <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Having said that, it would really depend on the topology, if the core is just one big broadcast domain & there being no or few redundant/alternative paths that traffic can take any of the above would be overkill and then using a number (that number is up to you) of strategically placed RR’s under the one AS to give all sites the correct next-hop address is probably the best option, OSPF would have significantly higher overhead than BGP in this instance.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If looking to expand/improve your BGP network have found the book ‘BGP Design and Implementation’ from Cisco Press to be very useful.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> ausnog-bounces@lists.ausnog.net [mailto:ausnog-bounces@lists.ausnog.net] <b>On Behalf Of </b>Tony<br><b>Sent:</b> Tuesday, 16 April 2013 10:13 PM<br><b>To:</b> Brad McGinn; ausnog@lists.ausnog.net<br><b>Subject:</b> Re: [AusNOG] VPLS OSPF question<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='background:white'><span style='color:black'>Hi Brad,<br><br>A bit of a "it depends" kind of question.<br><br>Do you have a VPLS setup right now, or moving towards one and wondering how to route across it ? You mention that you've currently got OSPF in your DC and the BGP into an MPLS network. Is the MPLS network provided by an SP, or you're doing that yourself ? If you're moving to VPLS, what are you hoping to gain ?<br><br>As someone else said, if using BGP you would want to have an RR setup, otherwise you need to create a full mesh (ie. each of your 200 sites would need 199 BGP sessions configured to each of the other routers -> disaster !). You'll also probably need two RR's for redundancy.<br><br>On the topic of large OSPF deployments, if you satisfy the following conditions:<br>- your links are reasonably stable<br>- you have a decent amount of bandwidth on all links<br>- the total number of routes is small<br>- routers are newish<br><br>then you would probably be able to run OSPF across 200 routers.<br><br>Taking each point in turn, the stability of links reflects how often each router will be running an OSPF calculation. One link flapping causes ALL routers to run an SPF calculation. If you have a continually flapping link this can cause issues. Bandwidth is important due to the amount of hello's and the size of the routing DB that will be transferred around on any link change. The number of routes and the number of routers are inversely related. If you have a massive number of routes being advertised then you would want a smaller number of routers in each area. If you're only advertising a single prefix from each of your 200 sites (eg. single /24) then that is the best possible option for scaling the size of OSPF. Decent router hardware today can handle a lot more OSPF routers in an area than when OSPF was first designed and the suggestion then was for a max of 30-50 routers per area due to HW limitations. CPU is used for running the OSPF algorithms, RAM is used to hold OSPF DB, you'll need sufficient of each in all routers as each router will be doing exactly the same thing (OSPF-wise anyway).<br><br>"Current ISP experience and Cisco testing suggest that it is unwise to have more than about 300 routers in OSPF backbone area 0, depending on all the other complexity factors that have been discussed. As mentioned in the preceding note, 50 or fewer routers is the most optimal design."<br><br>( <a href="http://www.ciscopress.com/articles/article.asp?p=1763921&seqNum=6">http://www.ciscopress.com/articles/article.asp?p=1763921&seqNum=6</a>)<o:p></o:p></span></p><div><p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>Breaking it up into smaller areas is probably the best idea to run OSPF. Without any knowledge of where your 200 sites are can you break it up into something like state based areas, or possibly business units ?<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>regards,<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>Tony.<o:p></o:p></span></p></div><div><blockquote style='border:none;border-left:solid #1010FF 1.5pt;padding:0cm 0cm 0cm 4.0pt;margin-left:3.75pt;margin-top:3.75pt;margin-bottom:5.0pt'><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><div><div><div><div class=MsoNormal align=center style='text-align:center'><span style='color:black'><hr size=1 width="100%" align=center></span></div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> Brad McGinn <<a href="mailto:the_xorach@yahoo.com">the_xorach@yahoo.com</a>><br><b>To:</b> "<a href="mailto:ausnog@lists.ausnog.net">ausnog@lists.ausnog.net</a>" <<a href="mailto:ausnog@lists.ausnog.net">ausnog@lists.ausnog.net</a>> <br><b>Sent:</b> Tuesday, 16 April 2013 5:14 PM<br><b>Subject:</b> [AusNOG] VPLS OSPF question</span><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><br><br><o:p></o:p></span></p><div id=yiv736869550><div><div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Hi AusNog list,<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Long time listener, first or second time caller.<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>I know this list is pretty specific to Service Providers so I'm hoping any of you who not only know carrier networks, but also have an insight into enterprise networks maybe able to help me to get a view (or even help understanding) of the pros and cons of running OSPF or BGP across a VPLS network. <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>I respectfully ask your advice. <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>I am an enterprise network engineer, not a service provider however I hope you don't hold that against me. We run OSPF in our Data Centre and BGP into a MPLS network that all of our sites connect into.<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>My fairly basic understanding of VPLS is kind of like EoMPLS or even one big broadcast domain. I assume any IGP could potentially work across it but some factors must be taken into consideration: eg flapping sites, latency, reference bandwidth, DR/BDR placement, multicast transmission and so on.<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>So, with that in mind, I'm wondering the following:<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>-<span class=yiv736869550tab> would it be wise to run an IGP across a VPLS backbone with over 200 sites? or would BGP be better? or even something else?</span><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>- if an IGP is the go, would one use OSPF?</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>- if OSPF, do you think it would be wiser to run a separate OSPF process for the VPLS connected sites and a separate OSPF process for the DC? and then redistribute or just summarise right there? (so as to protect the DC from OSPF recalculations when sites go up and down)</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>- if BGP would be the go I'm wondering how one might go about it.. I know that all iBGP neighbours must have a route to the peering IP of all other iBGP routers so I would assume an IGP must be run anyway???</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>- cisco say that anything more than 50 routers on an area is a bad idea, so if I have over 200 sites potentially on the VPLS, will OSPF cut it?</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>I guess i'm just trying to get my head around the different technology. I'd love to keep the stability that BGP brings, but also would like to be able to make use of the bandwidth that VPLS gives.</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Any hints or tips will be gratefully received and thank you for any help. If you would like to keep from cluttering up subscriber's inboxes, please reply offlist.</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Again, thanks for any help.</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span class=yiv736869550tab><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Regards,</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Brad David<o:p></o:p></span></p></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><span style='color:black'><br>_______________________________________________<br>AusNOG mailing list<br><a href="mailto:AusNOG@lists.ausnog.net">AusNOG@lists.ausnog.net</a><br><a href="http://lists.ausnog.net/mailman/listinfo/ausnog" target="_blank">http://lists.ausnog.net/mailman/listinfo/ausnog</a><br><br><o:p></o:p></span></p></div></div></div></blockquote></div></div></div></body></html>