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I agree with you!
Btw, in RFC 2547 hub&spoke VPN was described not so
deep.
Alternatively, suppose
one desired, for whatever reason, to create a
"hub and spoke" kind of
VPN. This could be done by the use of two
Target Attribute values, one
meaning "Hub" and one meaning "Spoke".
Then routes from the spokes could be
distributed to the hub, without
causing routes from the hub to be distributed
to the spokes.
Who knows, may be authors of
draft-ietf-l3vpn-rfc2547bis-03.txt will describe h&s VPN more
deeply.
Taras
Seems clear to me now.
Maybe in draft-ietf-l3vpn-rfc2547bis-03.txt it
should explicitly be said that the spoke and hub here does not offer
connectivity
between the spoke.
Fabien
----- Original Message -----
Sent: Wednesday, January 26, 2005 3:34 PM
Subject: RE: Route Target in BGP/MPLS IP VPN
Jim,
Fabien asked us about example in draft-ietf-l3vpn-rfc2547bis-03.txt
(4.3.5). In this examples authors show us how to build hub&spoke VPN without
any connectivity between spokes.
Btw, I agree with you. There is another kind of VPN called hub&spoke,
where traffic between spokes goes through hub. But it is not the case
of 4.3.5.
Marko,
As I can understand if you want to build hub&spoke VPN with
connectivity between spokes through hub, you have to organize one VPN per spoke.
Each VPN must be "point-to-point" (including one spoke site and separate
(sub)interface on hub site). Than you must organize routing between these
VPN on CE on hub Site.
So, we have as many different VPNs as spoke sites, you want to connect to
hub.
Cheers
Taras
Not exactly. It is actually both of these things and
connectivity between spokes is driven by configuration. In one model spokes
cannot communicate, in another they can (preferably via a firewall at the hub).
Jim Guichard CCIE# 2069
System Architect -
MPLS Technologies
ITD Boxborough
DD: 978-936-1586
Cell:
978-302-0481
Fabien: "What I
understood is that Spoke can not communicate DIRECTLY with each other. They
have
to go through the
Hub."
Taras:
No, spokes can not communicate with each other even
through hub. That is idea of hub&spoke VPN - it is VPN with PARTIAL
connectivity.
Suppose, you have a large data center and some clients of
data center. Clients want to reach data center, but they don't want have ANY
connectivity with other clients due security reasons, for
example.
As to BGP routing, I may say, that PE router on site B
(spoke Site) may receive all routes, including routes from site C. But it
does not install routes to site C in its VRF routing table. Route Target of
route from site C do not mach VRF "import" set of route target
attributes.
Taras
Thanks for your answer Taras ,
What I understood is that Spoke can not
communicate DIRECTLY with each other. They have
to go through the Hub.
But if a packet is received at PE C (from the
CE) for a destination address which is in site B he won't
have any route that says to go through the
Hub.
I'm talking about the routing between PEs when I
make a reference to RFC1771 9.2.1. Not between CE and PE.
Fabien
----- Original Message -----
Sent: Wednesday, January 26, 2005 1:29 PM
Subject: RE: Route Target in BGP/MPLS IP VPN
Hi,
The
main idea of Hub&spoke is the
following: spokes may communicate with hub, but spokes can NOT
communicate with each other.
So,
everything seems to be ok. Site A can communicate with site B & C, and
sites B & C can't communicate with each other.
As
I can understand we may use: RIPv2, OSPF and EBGP to make routing between PE
and CE. So RFC1771 9.2.1 it's not our case.
Cheers.
Taras
Hi,
I've got a question about the use of "Route Target" in
BGP/MPLS IP VPN
Section 4.3.5 of
draft-ietf-l3vpn-rfc2547bis-03.txt states:
"Alternatively, suppose one
desired, for whatever reason, to create a
"hub and spoke" kind of VPN. This could be done by the
use of two
Route Target values, one meaning "Hub" and one meaning
"Spoke". At
the VRFs attached to the hub sites, "Hub" is the Export
Target and
"Spoke" is the Import Target. At the VRFs attached to
the spoke
site, "Hub" is the Import Target and "Spoke" is the Export Target."
If I have 3 sites A,B,C. one CE/PE pair for each site and one VRF per
CE/PE.
Site A is the hub
Site B,C are spoke
In A VRF I would have the routes to both sites B and C
In B,C VRF I would only have routes to A since with BGP routes
learned from IBGP are not
advertised to BGP peer in the same AS (RFC 1771 9.2.1).
So how can systems in site B communicate with systems in site C?
I guess I misunderstood something, and PE connected to site A will
actually advertised routes received from site C
to site B. But it seems inconsistent with RFC 1771 9.2.1.
Can someone explain to me please?
Thanks
Fabien
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