re: [RRG] Re: Should the identifier be used as local locator

[Xu Xiaohu <xuxh@huawei.com>]

> |> Earlier Xu XiaoHu wrote:
> |> % Take GSE/ILNP as an example, the so-called identifier
> |> % is still used as routing hint in the site networks, ...
> |>
> |> The note referenced above does not correctly describe ILNP.
> |> I'll leave it to others as to whether it correctly describes GSE.
> |>
> |> - ILNP does NOT ever use the Identifier for
> |routing/forwarding packets.
> |> - The Identifier is only used for identity purposes in ILNP.
> |>
> |> - ILNP *only* uses the Locator to route/forward packets,
> |>   including when mobility or multi-homing are part of the deployment.
> |
> |Ran, after the Locator guides the packet to a subnetwork, does the
> |packet ever go through another IP router on its way to the destination
> |endpoint?  If so, how is it known what the next hop should be
> |to forward
> |the packet?
> 
> 
> And more specifically, how does the last hop router determine the MAC
> address of the final destination?  The MAC address itself is a flat
> identifier (and locator on the last hop) that can be embedded in the
> endpoint identifier, or the endpoint identifier can be used for a lookup
to
> determine the MAC address.  In either case, the endpoint identifier ends
up
> being used for a local routing decision.

Hi Tony,

Let me say that in other way, the MAC address, as locator on the last hop,
can be carried together with the endpoint identifier in the packets, or the
endpoint identifier can be used for a lookup to determine the MAC address.
The reason is that embedding the MAC address in the endpoint identifier is
not a good idea if we take the multi-interface hosts and the portability
requirement of identifier into account. Of course, there is a third way,
that is the last hop router just uses the identifier (IP address) as local
locator with the MAC address set to FF-FF-FF-FF-FF-FF, which just causes a
small-scale broadcast storm in the Ethernet network of the last hop. IMO,
the importance of the MAC address in the last hop is not as important as
that in the first and the middle hops.

Xiaohu XU
> 
> 
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