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Re: Class B Address
From: Matt Cramer <mscramer () armstrong com>
Date: Tue, 6 Jun 2000 13:06:10 -0400 (EDT)


On 20 May 2000, Sean Donelan wrote:

On Sat, 20 May 2000, Patrick Evans wrote:
And then watch certain tier-Ns filter out your routes?

As far as I know, every provider has relented and will accept
announcements on ARIN/RIPE/APNIC allocation bounderies.  Even
the original Sprint access-list 112 was modified to match the

The problem was people wanted to announce smaller blocks than
the allocation, e.g. /24's out of traditional class B/16 space.

Could I ask a question related to this topic?  I have been getting varying
answers and presume the accurate answer will come from this list.

My company has a /20 out of the traditional Class C space.  We want to use
those addresses rather than the addresses our ISP would give us.  We have
asked the ISP if they can announce a /24 out of that block, and they have
said "sure".  However, I have read here about announcement filtering.

Will certain providers filter that /24?  We have two reasons for using our
own space.  First, we can get redundancy by connecting with two ISPs and
having them both announce the network (or have one announce if the other
dies).  Second, we can carve up our /20 in /24s and use them for different
Internet POPs for our company (e.g. one in the states, one in Europe, one
in the Pacific Rim, etc.).

I am primarily a security person but unfortunately our LAN and WAN people
know less about this than I so I am trying to decide what we should do.
Any help or information about the logical design I mentioned would be
greatly appreciated.


- --
Matthew S. Cramer <mscramer () armstrong com>               Office: 717-396-5032
Lead Security Analyst                                    Fax:    717-396-5590
Armstrong Information Technology Services                Pager:  888-769-9367
Armstrong World Industries, Inc.                         Cell:   717-951-0141

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