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Rayhaan JaufeerallyandClaude Fable 5.1 1399cbd39f slides: "Hands-on BGP", restructured into five sections

- Title is now "Hands-on BGP"; the AS-path diagram is gone from the cover.
- Sections: IPv6 addresses and prefixes; where AS numbers and prefixes
  come from (IANA, RIRs, the RIPE database, IRR vs RPKI); BGP and the
  bytes of an UPDATE; IP transit vs Internet exchanges (the peering LAN as
  an Ethernet segment, route servers); the lab (ferrix, pr01.rue, SwissIX,
  NL-ix, France-IX, DE-CIX, transit).
- The UPDATE walked through in section 3 is a real 94-byte capture from
  ferrix for 2a0d:d741:1::/48. Vertical slides light up one part at a
  time with its decode; the generator asserted every quoted number
  against the capture. Session counts come from the tracked bird.conf,
  the route6 object from the RPSL file, SwissIX's LAN from PeeringDB.
- New components: focusable bytes, decode table, prefix bits, and SVG
  diagrams drawn in the theme's colours.
- Opening index.html straight from disk used to give a title and empty
  panels, because browsers block the module and the section files there.
  The page now explains that, and also reports a failed reveal.js load.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

2026-09-20 21:41:31 +02:00

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Where numbers come from

Notes: Section 2. Nobody "owns" addresses or AS numbers; they are registered to you.

A hierarchy of registries

IANA
the root

RIPE NCC
Europe, Middle East

ARIN

APNIC

LACNIC

AFRINIC

IANA hands large blocks to five regional registries. They hand smaller ones to members (LIRs), who assign to end users.

Notes: RIR = Regional Internet Registry. LIR = Local Internet Registry, a member of an RIR, typically an ISP. Our space comes from RIPE NCC via an LIR.

AS numbers

16 bits at first: 1 to 65535
32 bits since RFC 6793: up to 4294967295
Old routers see AS23456 (AS_TRANS) in place of a big one
Private use: 64512–65534 and 4200000000–4294967294

The lab daemon is AS4200000001. It is stripped before the Internet sees your route.

Notes: RFC 6996 reserves the private ranges. The upstream router removes the private AS from the path, so the origin everybody else sees is AS210036.

The RIPE database says who may announce what

route6:         2a0d:d741:1::/48
descr:          ETHZ Netsec 2026 BGP lab - student 1
origin:         AS210036
mnt-by:         mnt-ch-ray-1
source:         RIPE

One of these exists for every student prefix. Networks build their filters from them.

Notes: This is a real object; try the whois on the next slide. mnt-by names the maintainer: whoever holds its credentials can change the object. An inet6num object records the address block itself, a route6 object who may originate it.

Two ways to say "this origin is allowed"

	IRR (`route6`)	RPKI (ROA)
What it is	an entry in a database	a signed certificate
Who can create it	whoever holds the maintainer	only the holder of the addresses
Says	prefix + origin AS	prefix + origin AS + max length
Used for	building prefix filters	dropping "invalid" routes

Notes: Max length matters for us: a ROA for the /40 with max length 40 would make every student /48 RPKI-invalid, and many networks would drop it.

Look it up yourself

whois -h whois.ripe.net 2a0d:d741:1::/48
whois -h whois.ripe.net AS210036

Or in a browser: RIPEstat, bgp.tools, or a looking glass at an exchange.

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