Subject: [PWE3] PWE3 ethernet drafts - IESG aplicability statement request

From: Luca Martini <[email-masked]>
Date: Thu, 17 Nov 2005 17:27:44 -0700

WG,

The IESG review resulted in several minor clarification to be added to 
the pwe3 ethernet encapsulation draft.
I have fixed all the issues raised by the IESG review, and added the 
applicability statement below.
If you have any comments, please reply to this e-mail.

Thanks.
Luca

.Pa "Applicability statement"
The Ethernet PW emulation allows a service provider to offer a "port to
port" Ethernet based service across an MPLS packet switched network (PSN)
while the Ethernet VLAN PW emulation allows an "Ethernet VLAN to VLAN" based
service across an MPLS packet switched network (PSN).

The Ethernet or Ethernet VLAN PW has the following characteristics in
relationship to the respective native service:
.Px -
Ethernet PW connects two Ethernet ACs while Ethernet VLAN PW connects two
Ethernet VLAN ACs, supporting bi-directional transport of variable length
Ethernet frames. The ingress Native Service Processing (NSP) function strips
the preamble and FCS from the Ethernet frame and transports the frame in its
entirety across the PW. This is done regardless of the presence of the
802.1Q tag in the frame. The egress NSP function receives the Ethernet frame
from the PW and regenerates the preamble or FCS before forwarding the frame
to the attachment circuit. Since FCS is not being transported across either
Ethernet or Ethernet VLAN PWs, payload integrity transparency may be lost.
The OPTIONAL methods described in [FCS] can be used to achieve payload
integrity transparency on Ethernet or Ethernet VLAN PWs.
.Px -
For Ethernet VLAN PW, VLAN tag rewrite can be achieved by NSP at
the egress PE which is outside the scope of this document.

.Px -
The Ethernet or Ethernet VLAN PW only supports homogeneous Ethernet
frame type across the PW; both ends of the PW must be either tagged
or untagged.  Heterogeneous frame type support achieved with NSP
functionality is outside the scope of this document.

.Px -
Ethernet port or Ethernet VLAN status notification is provided
using the PW Status TLV in the LDP status notification message.
Loss of connectivity between PEs can be detected by the LDP
session closing, or by using [VCCV] mechanisms.  The PE
can convey these indications back to its attached Remote System.

.Px -
The maximum frame size that can be supported is limited by the PSN
MTU minus the MPLS header size, unless fragmentation and
reassembly is used [FRAG].

.Px -
The packet switched network may reorder, duplicate, or silently drop
packets. Sequencing MAY be enabled in the Ethernet or Ethernet VLAN PW
to detect lost, duplicate, or out-of-order packets on a per-PW basis.

.Px -
The faithfulness of an Ethernet or Ethernet VLAN PW may be
increased by leveraging Quality of Service features of the PEs
and the underlying PSN. (see "QoS Considerations" section)

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