Re: Next-Hop in IPv6 only environment

[Manav Bhatia <[e-mail]>]

Enke,
Then why does the draft-ietf-idr-bgp4-18.txt still mention the NEXT_HOP
field as a well-known mandatory attribute. If it isn't required for some
extensions then i believe we must mention it somewhere.

Moreover, i have never come across any implementation which doesn't look
for this attribute when it receives an UPDATE message!

Regards,
Manav

----- Original Message -----
From: "Enke Chen" <[e-mail]>
To: "Manav Bhatia" <[e-mail]>
Cc: "Jeffrey Haas" <[e-mail]>; <[e-mail]>; "Mareline
Sheldon" <[e-mail]>; <[e-mail]>
Sent: Friday, February 14, 2003 8:43 AM
Subject: Re: Next-Hop in IPv6 only environment


> Hi, Manav:
>
> > Date: Fri, 14 Feb 2003 08:29:44 +0530
> > From: Manav Bhatia <[e-mail]>
> > Subject: Re: Next-Hop in IPv6 only environment
> > To: Jeffrey Haas <[e-mail]>,
> > Mareline Sheldon <[e-mail]>
> > Cc: [e-mail]
> > Reply-To: Manav Bhatia <[e-mail]>
> > Message-id: <0ab901c2d3d5$2417ceb0$[e-mail]>
> >
> > Jeff,
> > If you are not running a dual stack you still need an IPv4 address as a
> > next-hop (even though it wont be used) which will be used as a
mandatory
> > path attribute along with the ORIGIN and AS-PATH.
>
> This is not correct. As the nexthop value is carried in the MP_REACH_NLRI
> filed, the NEXTHOP attribute is not needed at all. Please See the
following
> text from RFC 2858:
>
> -------------------------------------------------------------------
> 2. Multiprotocol Reachable NLRI - MP_REACH_NLRI (Type Code 14):
>
>    An UPDATE message that carries the MP_REACH_NLRI must also carry the
>    ORIGIN and the AS_PATH attributes (both in EBGP and in IBGP
>    exchanges).  Moreover, in IBGP exchanges such a message must also
>    carry the LOCAL_PREF attribute. If such a message is received from an
>    external peer, the local system shall check whether the leftmost AS
>    in the AS_PATH attribute is equal to the autonomous system number of
>    the peer than sent the message. If that is not the case, the local
>    system shall send the NOTIFICATION message with Error Code UPDATE
>    Message Error, and the Error Subcode set to Malformed AS_PATH.
> ---------------------------------------------------------------------
>
> -- Enke
>
> >
> > --
> > Manav
> >
> > ----- Original Message -----
> > From: "Jeffrey Haas" <[e-mail]>
> > To: "Mareline Sheldon" <[e-mail]>
> > Cc: <[e-mail]>
> > Sent: Thursday, February 13, 2003 11:43 PM
> > Subject: Re: Next-Hop in IPv6 only environment
> >
> >
> > > On Thu, Feb 13, 2003 at 06:59:59AM -0800, Mareline Sheldon wrote:
> > > > If your network is IPv6 only then you must somehow give some IPv4
> > address which this router
> > > > may use as the next-hop when advertising BGP UPDATE messages. One
way
> > could be through CLI.
> > >
> > > If the boxes, as shown below, are NOT running dual stack, then an
> > > IPv4 nexthop is nonsense.  IPv4 reachability should be discarded.
> > >
> > > > Mareline S.
> > > >
> > > > --- Manav Bhatia <[e-mail]> wrote:
> > > > > Hi,
> > > > > I guess in case of IPv6 only environment then one necessarily
needs
> > to
> > > > > configure a Router ID which will be filled in the mandatory
fields.
> > But
> > > > > then if the Router ID is non-routable then one cant advertise
IPv4
> > > > > reachability information using that peering !!!
> > > > >
> > > > > Is this correct?
> > > > >
> > > > > Regards,
> > > > > Manav
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Manav Bhatia" <[e-mail]>
> > > > > To: <[e-mail]>
> > > > > Sent: Thursday, February 13, 2003 2:36 PM
> > > > > Subject: Next-Hop in IPv6 only environment
> > > > >
> > > > >
> > > > > > Hello,
> > > > > > I have a very basic doubt in implementing BGP extensions for
IPv6
> > > > > > Inter-Domain Routing.
> > > > > >
> > > > > > Consider two routers (not running dual stack) as shown in the
> > figure.
> > > > > >
> > > > > > -----------                    --------------
> > > > > > |               |                    |                    |
> > > > > > |  peer 1   |    IPv6         |     peer2      |
> > > > > > |               | ------------ |                    |
> > > > > > |               |                    |                    |
> > > > > > -----------                   ---------------
> > > > > >   3ffe :: aa                         3ffe :: bb
> > > > > >
> > > > > > They are peered up using IPv6 addresses using TCP over IPv6.
Which
> > is
> > > > > then
> > > > > > the IPv4 next-hop which shall be used in all the BGP UPDATE
> > messages.
> > > > > Does
> > > > > > it need to be explicitly configured or is one of the
global/local
> > IPv6
> > > > > > addresses converted into IPv4 and used. How is it done?
> > > > > >
> > > > > > In case of dual stack one can look into the interface over
which
> > the
> > > > > > peering takes place and use that IP address as the next-hop.
But
> > what
> > > > > > happens in case of IPv6 only?
> > > > > >
> > > > > > Regards,
> > > > > > Manav
> > >
> > > --
> > > Jeff Haas
> > > NextHop Technologies
> > >
> >
>
>