# ROUTING POLICY FOR GRNET AS5408)
General Info
==============
GRNET donwstream customers are Greek Universities, Academic
and Research Institutes
GRNET has GEANT as its upstream; it also connects to GRIX
Internet Exchange
RPKI in GRNET
==============
GRNET ***drops*** ALL RPKI invalid prefixes received from Upstream
and Greek Internet Exchange (GR-IX)
PA Space Aggregation
=============
GRNET aggregates its PA space before announcing it to its
upstream(s) and exchanges. Should a customer with PA space
wishes not to have its prefixes aggregated, a special community
should be used to tag this route (see below).
Prefixes from GRNET allocation that announced from public ASs
are announced deaggregated.\
Prefix lengths longer than /24 for IPv4 and /48 for IPv6 are NOT
announced to Upstream or GRIX
Primary/Backup control
========================
GRNET respects the MED received by its customers; thus, the
customers can indicate their primary/backup line and control
incoming traffic by setting MED appropriatelly. Also, the
customers may use the community 5408:110 to indicate their
backup connection (lower local pref), but this method is
recommended only for customers multihomed to another Greek ISP
that use their connection with GRNET as backup.
Hot Potato routing
========================
By setting the same attributes (Local Preference and MED) on
advertising prefixes, a customer with more than one connections
with GRNET has the ability to use all active paths.
By this way, “hot potato” routing is achieved. Traffic will exit
GRNETs network choosing the closest to destination border router.
Anycast
========================
GRNET does not follow any explicit policy for anycast services.
Normal routing (and, thus, preference) applies to all anycast
routes
BGP Communities used in GRNET:
================================
Informational Communities:
+—————————————————————+
| These communities tag the source of the routes. They can ONLY |
| be appended by GRNET. Routes with this tag received by any |
| peer will be rejected! |
+—————————————————————+
5408:1001 Routes received from GEANT
5408:1002 Routes received from GRIX
5408:1003 Routes from GRNET (Customers & BackBone)
5408:1004 Routes from GEANT NREN
5408:1005 Routes from GEANT IAS
5408:1006 Routes from GEANT CLS
Special Communities for route manipulation:
+—————————————————————+
| These communities tag the source of the routes. They can ONLY |
| be appended by GRNET. Routes with this tag received by any |
| peer will be rejected! |
+—————————————————————+
5408:2000 Do not aggregate
5408:2005 Prepend AS5408 x5
5408:4001 Do not announce to GRIX
5408:4005 Do not announce to GEANT
5408:4006 Do not announce to GEANT NREN VRF
5408:4007 Do not announce to GEANT Tier-1
Routing Manipulation (for GRNET customers only):
+—————————————————————+
| This set of tools allow GRNET clients to manipulate their |
| routing: |
LOCAL PREFERENCES IN GRNET:
=============================
LocalPref 200: – GRNET Customers
– Special Customers (KROOT, SYZEYXIS, …)
– Locally Generated GRNET Aggregates
LocalPref 190: – GRNET Customers, backup connection
LocalPref 180: – GEANT NREN VRF
LocalPref 170: – GRIX routes (MED=0 Primary, MED=20 Secondary)
LocalPref 160: – GEANT CLS VRF
LocalPref 150: – GRNET as backup in dual homed customers
LocalPref 140: – GEANT IAS VRF
=======================================================================
iBGP (AS5408)
———————————————————————-
PEER DESCRIPTION:
Full-mesh iBGP peerings.
Import Policy: Accept ANY
Export Policy: Advertize (a) all routes (FIRT) or (b) GRNET & GRIX
routes only, depending on router capabilities.
======================================================================
=======================================================================
GEANT (AS20965)
———————————————————————-
PEER DESCRIPTION:
GEANT is the Internet Upstream for GRNET
Import Policy: Accept all routes (apart from martians),
set MED appropratelly on primary & backup peering.
Export Policy: Announce all GRNET routes (tagged with 5408:1003)
that are not tagged with 5408:4005 (don’t-announce-to-geant).
Aggregate PA space (except from the routes tagged with
5408:2000 (do not aggregate) community.
=======================================================================
=======================================================================
GRIX Peers
———————————————————————-
PEER DESCRIPTION:
These are the GRIX Peers of GRNET
Import Policy: Reject routes tagged with special communities
Accept all other routes that
(a) have the appropriate AS path and
(b) originate from the peer (or behind it)
For these, and according to the received communities:
(i) Set the appropriate local preference
Export Policy: Announce all GRNET routes (tagged with 5408:1003)
that are not tagged with 5408:4001 (don’t-announce-to-grix).
Aggregate PA space (except from the routes tagged with
5408:2000 (do not aggregate) community.
=======================================================================
=======================================================================
GRIX RS
———————————————————————-
=======================================================================
=======================================================================
GRIX ROUTER @ GRIX
———————————————————————-
=======================================================================
=======================================================================
K-ROOT mirror @ GRIX
———————————————————————-
PEER DESCRIPTION:
K-ROOT @ GRIX. Accept K-Root routes, announce within GRNET *only*
Announce default route.
=======================================================================
=======================================================================
GRNET Clients
———————————————————————-
PEER DESCRIPTION:
These are the normal GRNET clients (Universities, Research orgs, etc)
Import Policy: Reject routes tagged with special communities
Accept all other routes that
(a) have the appropriate AS path and
(b) originate from the client (or behind it)
For these, and according to the received communities:
(i) Set the appropriate local preference
Prefixes with no corresponding exact matching route on the
RIPE whois database are only accepted if tagged with NO_EXPORT
Local Preference (on backup links) can be lowered by
using the appropriate community (5408:110), but MED is
recommended for this purpose.
Export Policy:
(a) either all routes (FIRT)
(b) or a partial routing table, consiting
GRNET (5408:1003) and GRIX (5408:1002) routes
(c) or a partial routing table, consiting
GRNET (5408:1003) and GRIX (5408:1002) routes plus default route 0/0.
(d) or default route 0/0.
=======================================================================
=======================================================================
EU ACADEMIC INTERNET (GRNET + OTHER EU NRENS)
———————————————————————-
PEER DESCRIPTION: announce GRNET and GEANT NREN (community 20965:155), route within GRNET *only*.
=======================================================================
=======================================================================
GRNET SERVICES
———————————————————————-
PEER DESCRIPTION:
do not announce anything, accept AS65500
=======================================================================
=======================================================================
GRNET ECI-ECN
———————————————————————-
PEER DESCRIPTION:
do not announce anything, accept AS65502
=======================================================================
=======================================================================
SYZEYXIS
———————————————————————-
PEER DESCRIPTION:
announce only GRNET routes, route within GRNET *only*.
=======================================================================
=======================================================================
AKAMAI
———————————————————————-
PEER DESCRIPTION:
AKAMAI. Accept no routes. Announce GRNET customers.
=======================================================================
=======================================================================
# END OF ROUTING POLICY FOR GRNET
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For complains about abuse, spam etc:
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The above information was collected from whois.ripe.net, using
object “AS5408” on November 1, 2026