North American Network Operators Group

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Customer AS

  • From: Tim Crowell
  • Date: Thu Aug 15 14:55:43 1996

Howdy folks,

I would like to pose a question to the group about the best way 
to implement the following;

GTE has a customer who is a content provider that we have 
allocated a class C out of our CIDR block.

They have subsequently also ordered a second transit service 
from ISP XYZ.

Our assumptions are:
1. Customer will obtain an AS number to do BGP with both GTE and 
XYZ.  
2. BGP will be established with both ISPs
3. GTE will announce the class 'C' as both a part of our 
aggregate CIDR block and as a specific /24. 
4. XYZ will announce the class 'C' as a /24 only.
5. Both GTE and XYZ will supply a default route.  

Explanation/Questions;
1. Does this AS number have to be an officially registered AS or 
can it be a reserved number?  The thought is that the Class 'C' 
will be announced by both ISPs and strip the customers AS.  The 
AS would only be used to connect between ISPs.
It seems extremely wasteful for every little company that wishes 
a dual homed network would have to get a registered AS.  

2. We first had major heartburn with carving the 'C' out because 
we just couldn't see having to add 2 additional announcements to 
the internet routing tables but we have come to the conclusion 
that there is no other way to do it. We assume that we have to 
announce the /24 in addition to our aggregate otherwise XYZ's 
more specific announcement of our network would route all 
traffic through them from the internet.  It just seems that if 
there were a large number of these multi-homed Class 'C's that 
the internet routing table would be flooded.  (Maybe thats a 
part of the problem.

3. As a followup,  what would you do if a subnetted class 'C' 
customer  who only requires a dozen or so addresses but orders 
connections to two ISP's.  Do you burn a whole Class 'C' ????

4. Is there anyway to accomplish what the customer wants that we 
haven't considered.

5. I understand that we will have to submit the Class C to RADB 
and create a "hole" in our aggregate to effectively represent 
the network topology.

Thanks for any assistance,

PS.  If i'm just being stupid about this feel free to say so.  I 
don't pout too long.

-- 
Tim Crowell - GTE Intelligent Network Services
tcrowell@gte.net		Voice: 214.751.3881
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