Subject: Review of draft-ietf-l3vpn-ospf-2547-01.txt

From: Christian Hopps <[email-masked]>
Date: Mon, 15 Mar 2004 11:47:18 -0800

Mostly all I have is editorial comments, which follow.

>           OSPF as the PE/CE Protocol in BGP/MPLS IP VPNs
[...]

>      - If VPN sites A and B are in the same OSPF domain, then routes
>        from one should be presented to the other as OSPF intra-network
>        routes.  In general, this can be done by presenting such routes
>        as inter-area routes, in type 3 LSAs.

Does the term "OSPF intra-network routes" here really mean "OSPF 
intra-domain routes"?

[...]

>    If two PEs attach to different VPN sites that are in the same OSPF
>    area (as indicated by the OSPF area number), the PE/CE links to 
> those
>    site MAY be treated as links within that area. In addition, each PE

sites

[...]

>    If a PE router needs to use OSPF to distribute to a CE router a 
> route
>    which comes from a site outside the CE router's OSPF domain, the PE
>    router SHOULD present itself to the CE router as an Autonomous 
> System
>    Border Router (ASBR), and SHOULD report such routes as AS-external

Why is the first "SHOULD" not a "MUST"?

>    routes.  That is, these PE routers originate Type 5 LSAs reporting
>    the extra-domain routes as AS-external routes. Each such Type 5 LSA
>    MUST contain an OSPF route tag whose value is that of the VPN Route
>    Tag.  This tag identifies the route as having come from a PE router.
>    The VPN Route Tag MUST be used to ensure that a Type 5 LSA 
> originated
>    by a PE router is not redistributed through the OSPF area to another
>    PE router.

[...]

>      - OSPF Route Type Extended Communities Attribute. This attribute
>        MUST be present.  It is encoded with a two-byte type field, and
>        its type is 0306. The type 8000 SHOULD be accepted as well, to
>        ensure backwards compatibility.  The remaining six bytes of the
>        Attribute are encodes as follows:
>
>          * Area Number: 4 bytes, encoding a 32-bit area number. For AS-
>            external routes, the value is 0. A non-zero value identifies
>            the route as being internal to the OSPF domain, and as being
>            within the identified area. Area numbers are relative to a
>            particular OSPF domain.

Perhaps there should be the std "bits" diagrams for this and the other 
attributes?

[...]

> 4.2.4. VPN-IP routes received via BGP
>
>    This section describes how the PE router handles VPN-IP routes
>    received via BGP.
>
>    If a received BGP VPN-IP route is not installed in the VRF, nothing
>    is reported to the CE. A received route will not be installed into
>    the VRF if some other route is preferable. (Note that a route which
>    is not installed in the VRF may still cause the PE to create an OSPF
>    link to another PE as specified in the previous section.)

Perhaps a section reference here rather than "previous".

Chris.

---

From: Alex Zinin <[email-masked]>
Date: Sat, 20 Mar 2004 11:47:45 -0800

Thanks, Chris!

I'm cc'ing the L3VPN WG chairs who should be able to take this
to the WG.

-- 
Alex
http://www.psg.com/~zinin/