I think it should be pointed out here that the land mine isn't even
linking the customers IGP to the ISP's IGP. The land mine is linking the
IGP's of the customers to each other. Consider having 1000 customers, all
advertising their nets to this IGP, then consider what happens when one of
them decides to makes a net entry that is flat out wrong. For instance,
customer A decides he now wants to add network B and starts advertising it
in the IGP to the ISP. Customer B and the ISP suddenly have major problems.
The only way to prevent this to is install route filters for all 1000
customers. And fixing it after it happens is a major nightmare. And do you
really think every one of those 1000 customers will advertise their networks
correctly?
Personally, I find it much easier and safer to do 1000 static routes.
The solution below only works if the ISP has sole control of each of the
1000 customers edge routers. And again, 1000 static routes is more
reasonable than adding the burden of managing 1000+ more routers. Imagine
the password nightmare (or did you really expect to put the same password on
the routers of two different customers?). So now we add a RADIUS server.
Don
""Mike Bernico"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> 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
Message Posted at:
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