Vyatta as a BRAS

Joe Greco jgreco at ns.sol.net
Fri Jul 16 08:53:04 CDT 2010

> I got a router, it's got 5-6 10GE interfaces talking to other routers on
> my network backbone, and a bunch of 10GE links to end-user-facing aggregation
> switches. Since it's only forwarding inside my network, it's a core router
> by your definition.
> I now turn up an identical hardware 10GE link - connected to Level3. I just
> became an edge router by your definition since I'm talking to another network.
> (I know, I probably don't want to do that - but I *could*, maybe even without
> a full BGP feed if the routing situation allows. The point is the definition
> is busticated).
> Adding to the confusion is the fact that the edge routers of some large providers
> need more capacity than the core routers of smaller organizations....

There's a problem here in that some people want 'core router' to mean
'biggest fscking router', while other people want a functional 
definition that explains a router's role in the design of a network.

For an enterprise, for example, it doesn't make sense for them to have
a router in the middle of their network and then tell them "but you can
not call it your core router, because that term is reserved for routers
with 200g or more capacity per slot (Jared's def'n)."

I'm going to submit that the "big fscking router" definition is stupid
and meaningless, because today's big fscking router is tomorrow's small
aggregation router, and then a few years later just a coffee table stand.
Hello, 7513 from .. what, 1995?  :-)

A more customary understanding of border, core, etc., can be found in
places like RFC4098.

Generally speaking, a core router is an internal router, i.e. one that
speaks only to other devices/endpoints/whatever in the same AS.  Various
refinements to the definition might want it to speak BGP, etc.

That definition is very reasonable.  A small enterprise with a DS3 to the
'net has a border router that connects them to their ISP, which connects
to a firewall/IDS that protects their net, and then a core router that
connects all their internal networks and links to the firewall for 
external connectivity.  You could talk to most network engineers and 
they'd understand the terminology without further explanation.

There are of course problems with the core and border definitions as
well, of course, such as what happens when you connect a core router
interface to an upstream and you wind up with a mongrel.  However, the
"core means bfr" definition strikes me as singularly useless and
something that's really more marketingspeak from router vendors who
would like you to think of these routers powering the core of the
Internet, or whatever.

... JG
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.

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