[j-nsp] IPv6

Richard A Steenbergen ras at e-gerbil.net
Sat Jan 23 13:13:41 EST 2010

On Sun, Jan 24, 2010 at 01:57:32AM +0800, Mark Tinka wrote:
> On Sunday 24 January 2010 01:31:22 am Richard A Steenbergen 
> wrote:
> > * Juniper does something weird with next-hop self, which
> >  causes a lot of grief when you want to do ipv4/ipv6 dual
> >  stack. Basically the problems is there isn't an
> >  "update-source <interface>" option like Cisco has, so
> >  the next-hop self value is taken from the local address
> >  of the BGP session rather than from any particular
> >  interface. So when you carry ipv4+piv6 AFIs over a
> >  single IBGP session (using for example an IPv4 address
> >  as transport), and you do a next-hop self, it sets the
> >  v6 nexthop to ::i.p.v.4 rather than a proper v6 address.
> >  You can avoid setting next-hop self in most cases, but
> >  it's pretty hard to avoid when you're doing prefix
> >  origination. IMHO the easiest way to work around this is
> >  just to make an ::i.p.v.4 alias on your lo0 and carry
> >  both values in your IGP, but it's something to keep in
> >  mind.
> Curious, did you have any particular reasons you chose to 
> carry both v4 and v6 NLRI in a single iBGP session, as 
> opposed to running independent sessions for each AFI on the 
> same wire?

Convenience. Obviously with eBGP there are other reasons to run two
sessions (like liveness tests), but with iBGP there is no inherent
reason why you'd need to duplicate your BGP mesh. Cisco does the right
thing w/next-hop-self, you just have to work around this behavior with
Juniper NHS.

Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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