Hey Daren, For single homed customers, that makes a lot of sense. I suppose I was speaking more to the situations where a customer my want to dynamically advertise reachability to their provider(s)
At 04:32 PM 10/4/2002 +0000, Daren Presbitero wrote: >What about using default routes at the customer sites? > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of >Peter van Oene >Sent: Friday, October 04, 2002 5:17 AM >To: [EMAIL PROTECTED] >Subject: Re: OSPF for ISPs [7:54540] > > >At 07:12 PM 9/30/2002 +0000, MADMAN wrote: > >Interesting. I don't work for an ISP bt have worked with many and I > >have only ran into one that ran an IGP with it's customers and I was > >suprised. My ancedotal evidence suggests that the vast majority either > > >run BGP or statics to announce customer networks. I know there are > >plenty of ISP engineers out there and can confirm/rip my conjecture ;) > > > > Dave > >Best practises would dictate the use of static or a distance vector >variant >IGP for customer connections. The lack of import filtering capability >in >Link State protocols presents a very dangerous situation for the ISP. >In >general, ISP's are very paranoid about customers (and peers/providers >alike) and take all means necessary to protect themselves from >misbehaving >external peers (IP peers in this general case) BGP naturally provides >the >most policy rich tool set for those applications where static routing >will >not suffice. I find RIP to be a comfortable variant for those >multihomed >customers who simply will not turn up BGP, though I'd still prefer to >have >the BGP discussion one last time with them prior to doing using it. > >Of course, linking one's main IGP to a customers is a really silly idea >which I think everyone grasps ;) > > > > >Mike Bernico wrote: > > > > > > I'm not sure I'm in complete agreement. The network I work for has >several > > > distribution routers that contain around 1000 T1 speed customers. > > > If we were to static route each of their networks it would add about > > > > 1000 to >1500 > > > lines of router configuration to the router. That would definately > > > add >to > > > our maintenance and provisioning work and make troubleshooting > > > harder on > >our > > > techs. While I agree statics are probably the most stable way, I'm >not > > > sure it's necessarily the best way to aggrigate high volumes of >customers. > > > We currently use EIGRP at the edge with the stub command, OSPF or > > > IS-IS would work just as well. Regardless, we would never let our > > > IGP, that extends to the CE router, touch their IGP. About 98% of > > > our customers >are > > > not BGP customers though. > > > > > > YMMV > > > Mike > > > > > > ------------------- > > > Mike Bernico [EMAIL PROTECTED] > > > Illinois Century Network http://www.illinois.net > > > (217) 557-6555 > > > > > > > -----Original Message----- > > > > From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] > > > > Sent: Monday, September 30, 2002 11:37 AM > > > > To: [EMAIL PROTECTED] > > > > Subject: Re: OSPF for ISPs [7:54540] > > > > > > > > > > > > At 2:58 PM +0000 9/30/02, Don wrote: > > > > >Rather than run OSPF to customers, it is generally much > > > > better to have > > > > >them use a default route to the ISP and for the ISP to run > > > > static routes to > > > > >the customer. OSPF to the customer is a huge land mine for > > > > the ISP and > > > > >should be avoided in almost every case. > > > > > Don > > > > > > > > I agree completely with Don that an ISP _never_ should link its > > > > IGP to that of the customer. Don't fall into the trap of assuming > > > > > that BGP needs a full routing table or will consume excessive > > > > resources. > > > > > > > > I remain confused why a default route wouldn't serve, unless there > > > > > are multiple connections between the ISP and customer. By "send > > > > the block to the customer," do you mean the block is in the > > > > customer's space? You could certainly use a second static route, > > > > which can be generated automatically as part of your address > > > > assignment (see my NANOG presentation, > > > > http://www.nanog.org/mtg-9811/ppt/berk/index.htm). > > > > > > > > If that's not appropriate, have the customer announce his two > > > > blocks to you with BGP and receive default from your BGP. > > > > > > > > > > > > > > > > > > >""Chris Headings"" wrote in message > > > > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > >> Good morning all. I was wondering if someone could lend > > > > me a little help > > > > >> about engineering OSPF in the backbone for an ISP > > > > network. I just had a > > > > >> couple of questions and hopefully someone can give me > > > > some guidance.or > > > > >even > > > > >> some CCO links with some specific examples or better yet > > > > any material > > > > >> anywhere. > > > > >> > > > > >> Say, for example, that a customer has a small block of IP's > > > > >> and a distribution router knows where that block is, via a > > > > connected route, > > > > like > > > > >a > > > > >> /30 on a serial link. But later down the line the > > > > customer requests an > > > > >> additional block of 64 IP addresses, what is the best way > > > > to send this > > > > >block > > > > >> to the customer? Do I need to run OSPF on the customer > > > > equipment? If > > > > the > > > > >> customer router is not running OSPF, how do the routers > > > > know how to get > > > > to > > > > >> this destination? I assume via static routing??? > > > > >> > > > > >> Thanks as always. > > > > >> > > > > > > Chris > >-- > >David Madland > >CCIE# 2016 > >Sr. Network Engineer > >Qwest Communications > >612-664-3367 > > > >"You don't make the poor richer by making the rich poorer." --Winston > >Churchill Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54905&t=54540 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
