[j-nsp] 6PE without family inet6 labeled-unicast

[Pavel Lunin]

Errata

>So your BGP route will not be inactive because of the unreachable
next-hop.

So your BGP route *will be* inactive because of the unreachable next-hop.


On Sun, Jul 22, 2018 at 11:52 PM, Pavel Lunin <plunin at gmail.com> wrote:

>
>
> On Sun, Jul 22, 2018 at 9:45 PM, Andrey Kostin <ankost at podolsk.ru> wrote:
>
>> Hi Pavel,
>>
>> Thanks for replying. I understand how it works as soon as proper next-hop
>> is present in a route. My attention was attracted by implicit next-hop
>> conversion from pure IPv4 address to IPv4-mapped IPv6 next-hop from
>> "Nexthop: YYY.YYY.155.141" in the advertised route to "Protocol next hop:
>> ::ffff:YYY.YYY.155.141" in the received route.
>>
>
> This is normal. In order to announce AFI/SAFI 2/1 update, you must have an
> IPv6 next-hop. This is why it gets automatically converted. If you enable
> BGP-LU, nothing will change in this terms, your next-hop address will still
> be an IPv4-mapped IPv6 address. It will just be labeled.
>
> Same thing happens when you perform next-hop-self (or it's eBGP) for an
> IPv6 route, announced via an MP-BGP session over IPv4.
>
> And ipv6-tunneling under mpls stanza is what makes your LDP/RSVP routes be
> leaked from inet.3 to inet6.3 with automatic v4-to-v6 mapping. It's a
> syntactic sugar, you can do the same with policies, explicitly leaking
> inet.3 to inet6.3.
>
> I'm also wondering what could happen is there are no LSP available, which
>> is rather unreal situation because everything will be broken anyway in this
>> case.
>>
> If no LSP/FEC is available for the v4-mapped IPv6 next-hop, you won't have
> an LDP/RSVP route in inet.3, thus it won't be leaked to inet6.3. So your
> BGP route will not be inactive because of the unreachable next-hop. And
> not, it's not so unusual. You can easily have your IGP up and running, but
> someone forgot to add MPLS on one of the core interfaces. So your BGP
> session and routes are up, IGP works but there is no labeled next-hop in
> inet.3.
>
> --
> Pavel
>