Sprint BGP filters in 207.x.x.x?

Dave Siegel dsiegel at rtd.com
Wed Dec 13 18:57:41 UTC 1995

> MCI aggregates all its customer's routes into /19's.  We have just
> received our first block of address space from the 207.x.x.x range.  If
> you continue to filter at /18's for the 207.x.x.x range, you won't be
> able to reach all of MCI's customers.
> Needless to say MCI would appreciate it if you'd change your policy to be
> /19's, and I'm sure Sprint's customers would appreciate it as well.
> ==========
> Aside from what Daniel says about Sprint and MCI's routing policy 
> mismatch, this statement is interesting on another level.  For Dan says: 
> MCI aggregates all its customer's routes into /19's.  This is new is it 
> not?  Also it says *MCI* does the aggregating and not the customer.  

That may hold true internally, however, I suspect that externally, they 
announce only /16's or /15's.  Of course, I could be wrong.

What I see right now, is only one announcement from the 207 block...a /19 
coming from netaxs, and then some customer of PSI is announcing 5 or so
/24's in the 208 block!

> Would someone please explain how this differs from what I understand to 
> be Sprints policy which says (i believe) that it is the CUSTOMER's 
> responsibility to aggregate the routes they present to sprint???

Sprint already proxy-aggregates for many of their customers.  Most of them
probably don't realize it.  It doesn't even affect most of them.

> Why would MCI do the aggregating?  Is such mci policy good for mci or 
> good for the customer or equally good for both?

Depends on the situation as to whether it's detrimental.  Proxy-aggregation,
as this is called, can alter traffic patterns in dual-homed situations.  The
change is not always bad, though it is often un-desirable.

In general, proxy-aggregation is good for everybody.


Dave Siegel		     President, RTD Systems & Networking, Inc.
(520)623-9663		     Network Engineer -- Regional/National NSPs (Cisco)
dsiegel at rtd.com		     User Tracking & Acctg -- "Written by an ISP, 
http://www.rtd.com/~dsiegel/					for an ISP."

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