[nsp] AToM

[Lars Erik Gullerud]

On Tue, 2003-12-23 at 12:52, Maik Bachmann wrote:
> > If 1540 is in fact the physical MTU, you are short. The 1530 byte packet
> > is in itself a payload that is encapsulated in a local ethernet frame,
> > meaning another header+FCS will be added, i.e. another 18 bytes. The
> > actual ethernet frame you are transmitting over the wire is now 1548
> > bytes.
> 
> two times eternet framing ? Is this visible in e.g. ethereal or something
> similar ?

The "outer" Ethernet framing is just the local encapsulation and will
vary according to what kind of L2 media you are transmitting the MPLS
packets over. If your upstream interfaces are SONET, then you will have
a SONET header instead. Remember, this is just the "link-local"
encapsulation for any given link between your LSR's.

The inner Ethernet frame is after all not "your" Ethernet-frame, that's
the L2 frame you are transporting for your customer inside your L2VPN.
(or whatever you are using it for, the concept is the same).

/leg