Managing CE eBGP details & common/accepted CE-facing BGP practices
justin at justinshore.com
Sat Dec 20 19:22:41 CST 2008
Does anyone have any preferred ways to manage their customer-facing BGP
details? I'm thinking about the customer's ASN (SP assigned private ASN
or RIR assigned ASN), permitted prefixes, etc? While I'm sure this
could be easily stored in a spreadsheet I'm not sure if there is any
merit to storing some of these details outside of the configuration on
the PE (assuming of course that the PE's config is regularly archived).
Now if the PE's BGP config was auto-generated via a script then it
would make sense for all the details to be stored off in a DB in the
NOC. Beyond that is there a good reason to do archive it in a textual
format off of the PE and if there is a sound reason to do it, is therea
good or preferred way to do accomplish this?
We're moving beyond our typical residential and very small SMB service
to larger customers over the next few months. These areas have larger,
more advanced customers and I'm sure we'll run into multi-homed
environments and customer who will expect BGP peering options. I would
like to be prepared with sound practices before we get our first
customer that wants to get a default route via BGP, wants full tables,
or has their own ASN and is bringing their own PI space with them. Some
of this of course implies multiple processes to confirm that the ASN
belongs to the customer in question, that the PI space belongs to the
customer in question, notifying our upstreams to accept the customer's
PI space, etc. It's hammering out the scalable and best practice config
details that I'm concerned with at the moment.
When assigning private ASNs to customers, are there any gotchas to be
aware of? Is it possible to use the same private ASN for more than one
customer on the same PE?
What are common and accepted CE-facing BGP practices? MD5 AUTH, GTSM,
max prefix limits? Which is preferred, route-maps or prefix-lists for
controlling advertised and/or received routes? Do any SPs utilize
AS-Path ACLs to check that prefixes from an customer's ASN are claimed
to originate from there? Are there any SPs out there offering BFD
support for BGP or CE-facing peering sessions?
Should we have the customer announce their PA space to us or do we
advertise it for them (redist a static)? Do SPs restrict access to
tcp/179 on the CE from the Internet in the CE-facing ACL? Do SPs block
access to the PE-CE subnet from the outside world like what was
described in the Router Security Strategies book (pages 189-193)? What
about dropping incoming traffic to everything but the CE IP?
While I don't predict our CE-facing BGP load to be terribly significant
at this point, I would like to establish sound practices now rather than
down the road once we're neck deep in temporarily production workarounds.
Is there any consensus on what's best practice for CE-facing BGP? I
imagine most SP engineer's BGP practices could be better equated to a
religious holy war on par with Chevy vs Ford or Mac vs PC. I would be
interested in hearing what they are though and learning from the group's
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