Carlos,
Please see more comments
inline.
Regards,
Sasha
> -----Original
Message-----
> From: Carlos Pignataro [
mailto:cpignata <at> cisco.com]
> Sent: Wednesday, May 04, 2005 5:24 PM
> To:
Sasha Vainshtein
> Cc: Elena Vinkler; PWE3 WG (E-mail); l2tpext <at> ietf.org;
Alik
> Shimelmits;
> Sharon Galtzur
> Subject: Re: [PWE3] RE:
[L2tpext] Re: Local CE IP Address AVP
>
>
>
Sasha,
>
> Please see my comments inline.
>
> Circa
5/4/2005 11:16 AM, Sasha Vainshtein said the following:
> > Carlos and
all,
> > I have checked the set of the "LDP PW Types"
> > as
it appears in
> >
>
http://www.ietf.org/internet-drafts/draft-ietf-pwe3-iana-alloc> ation-09.txt
> > vs. the
set of "L2TP PW Types" as they appear in the drafts
> you refer
to.
> >
> > Here are the results:
> >
>
>
> >
--------------------------------------------------------------------
>
> PW
Type
| LDP | L2TP | Comment
>
>
| value | value |
> >
---------------------|--------|--------|----------------------------
>
> Frame Relay DLCI | 0x0001 | 0x0001 | 0x0001 is a
historic value
>
>
|
| | for the original Martini
>
>
|
| | encapsulation.
>
>
| 0x0019 | | 0x0019 is the value for
the
>
>
|
| | "standard" encapsulation.
>
>
|
| | The need for this value
>
>
|
| | has discovered recently
>
>
----------------------|--------|--------|----------------------------
>
> ATM AAL5 SDU | 0x0002 |
0x0002 |
> >
> >
---------------------|--------|--------|-----------------------------
>
> ATM Transparent Cell | 0x0003 | 0x0003 |
> >
Transport
|
| |
> >
---------------------|--------|--------|-----------------------------
>
> Ethernet VLAN | 0x0004 | 0x0004
|
> >
---------------------|--------|--------|-----------------------------
>
>
Ethernet
| 0x0005 | 0x0005 |
> >
---------------------|--------|--------|-----------------------------
>
> ATM N-to-1 VCC Cell | 0x0009 | 0x0009 |
> >
Transport
|
| |
> >
---------------------|--------|--------|-----------------------------
>
> ATM N-to-1 VPC Cell | 0x000a | 0x000a |
> >
Transport
|
| |
> >
---------------------|--------|--------|-----------------------------
>
> SAToP
E1 |
0x0011 | TBA |
> >
---------------------|--------|--------|
> > SAToP T1
(DS1) | 0x0012 | TBA
|
> > ---------------------|--------|--------|
> > SAToP
E3 |
0x0013 | TBA |
> >
---------------------|--------|--------|
> > SAToP T3
(DS3) | 0x0014 | TBA
|
> > ---------------------|--------|--------|
> > CESoPSN
basic mode | 0x0015 | TBA |
> >
---------------------|--------|--------|
> > TDMoIP basic
mode | 0x0016 | TBA |
> >
---------------------|--------|--------|
> > CESoPSN TDM with CAS |
0x0017 | TBA |
> >
---------------------|--------|--------|
> > TDMoIP TDM with CAS
| 0x0018 | TBA |
> >
---------------------------------------------------------------------
>
>
> > IMHO such a wonderful harmony (with the gaps in the L2TP PW
Type
> > values matching LDP PW Types that are not supported over
L2TP)
> > strongly suggests to me that the historical reasons
work
> differently,
> > namely that the authors of the L2TP PW
drafts have intentionally
> > aligned their allocation requests with
these for the LDP PW Types\
> > (existing since the early Martini
drafts). And in doing so
> > they have successfully ignored the
difference between
> > two octet values and 15-bit ones (look at the
notaion used!)
> >
> > TDM PW types somewhat break this
harmony, but hopefully this
> > will be fixed in the next revision of
the dratf.
>
> I personally don't believe that the 15-bit vs. 2
octet is the only
> difference: Besides the TDM PW Types discrepancy that
you noted,
>
[Sasha] To the best of my
knowledge, this is an omission, not a
discrepancy: an earlier
version of the draft has been posted
before the PW Types for the
TDM PWs have been formally allocated,
and the consequent updates
have simply missed the fact that
the allocation already
exists.
>
> there are 2 LDP FR
DLCI PW Types because of the FECN/BECN
> order reversal
in the control word, problem that does not
> exist in L2TPv3;
>
[Sasha] As I have said, the
need for two FR DLCI PW types
has been discovered only
recently. Of course the problem
does not exist in L2TPv3.
Personally I would say that two
PW Types are not really
needed for LDP either and FECN/BECN
order in the CW could be
easily signaled by a suitable
interface parameter (which,
if omitted, would indicate
Martini order to assure
backward compatibility)
>
> the ATM PW Types
have actually a different name/description (and from
>
draft-ietf-pwe3-iana-allocation-09.txt "description of up to 65
>
characters is required ...")
>
[Sasha] As much as I can
see it, the difference is in the words
"n-to-one" (present in the
PWE3 document and absent in the L2TPEXT
ones because no one
cares for one-to-one encapsulations for
L2TPv3: whatever BW gain can
be achieved, it is negligible once
the IP/L2TPv3 overhead is
considered)
>
> and the "one-to-one cell
mode" are not
> defined in L2TPv3 ATM document (it probably wouldn't make
sense to
> reference "n-to-one cell" PW Types from the L2TPv3 ATM document
if
> that's not defined). So from the table above, it seems to me that
only
> two PW Types are a true harmonic match.
>
[Sasha], Well, harmony (kind
of beauty) is in the eye of the beholder...
>
> Also, the two
number spaces have different allocation policies.
>
[Sasha] Is there any
non-historical reason for that?
>
> >
>
> So wouldn't it be better for all if the two name spaces were
> >
merged by declaring that the two-octet value is treated
> > as a 16-bit
integer in the network byte order, and the
> > LDP PW Type value is
placed into least significant 15 bits?
>
> IMHO, merging the two
name spaces would actually create a lot more
> confusion, not only because
of the discrepancies mentioned above, but
> also because the L2TPv3 PW
Type number space is already
> created as part
> of RFC3931, and
L2TPv3 documents past last call already suggest values
> for IANA
allocation in that number space. I believe the only
> place where
>
the two spaces would meet is in the PW-IW case, in which case
> IMHO an
IW
> consideration (and possibly the simplest) relates to the PW
Type
> (further simplified in practice by the actual requested values)
along
> with all other IW considerations. So it would seem to me that
there is
> really not a specific problem for the current state. Let's see
if
> there's other opinions.
>
[Sasha] The last suggestion
is OK with me.
>
> Regards,
>
>
--Carlos.
>
> >
> > IMHO this would save lots of
unncessary trouble...
> >
> > Regards,
>
>
Sasha
> >
> >>-----Original Message-----
>
>>From: Carlos Pignataro [
mailto:cpignata <at> cisco./om]
> >>Sent: Wednesday, May
04, 2005 3:38 PM
> >>To: Sasha Vainshtein
> >>Cc: Elena
Vinkler; PWE3 WG (E-mail); l2tpext <at> ietf.org; Alik
>
>>Shimelmits;
> >>Sharon Galtzur
> >>Subject: Re:
[PWE3] RE: [L2tpext] Re: Local CE IP Address AVP
> >>
>
>>
> >>Sasha,
> >>
> >>Please see a
couple of comments inline.
> >>
> >>Circa 5/4/2005 6:19
AM, Sasha Vainshtein said the following:
> >>
>
>>>Carlos and all,
> >>>Please see a brief comment
inline.
> >>>CC'ing also the PWE3 WG
> >>>I have
snipped the parts that are not relevant to this comment.
>
>>>
> >>>Regards,
> >>>
Sasha Vainshtein
>
>>>e-mail:
sasha <at> axerra.com
> >>>phone:
+972-3-7659993 (office)
>
>>>mobile:
+972-52-8674833
> >>>
> >>>
>
>>>
> >>>>-----Original Message-----
>
>>>>From: Carlos Pignataro [
mailto:cpignata <at> cisco.com]
> >>>>Sent: Saturday, April 30, 2005
9:46 PM
> >>>>To: mark <at> mjlnet.com
> >>>>Cc:
l2tpext <at> ietf.org
> >>>>Subject: Re: [L2tpext] Re: Local CE IP
Address AVP
> >>>>
> >>>
>
>>>... snipped ...
> >>>
> >>>
>
>>>>>>For example, a PW Type for IP-L2
>
>>>>>>Transport is not yet defined (in any draft and thus
not
> >>>>>
> >>>>>allocated),
>
>>>>>
> >>>>>I thought that IP L2 transport
had been allocated the PW type
> >>>>>0x000B, hadn't
it??
> >>>>>
> >>>>
>
>>>>No. The link below Section 2. (or 2.1. in version -09)
>
>>
> >>references the
> >>
>
>>>>LDP (FEC128/129) "Pseudowire Type", which is a 15-bit
>
>>
> >>quantity (1 bit
> >>
>
>>>>used in the FEC Element for Control-word).
>
>>>> IANA needs to set up a registry of "Pseudowire
Type".
> >>>>These are 15-
>
>>>> bit values.
> >>>>
>
>>>>In contrast, "L2TPv3 Pseudowire Types" uses a different
>
>>>>number space or
> >>>>registry created as part
of RFC3931 (see Section 10.6) for
> >>>>these 16-bit
>
>>>>quantities:
> >>>> The Pseudowire Type
(PW Type, see Section 5.4) is a
> 2-octet value
>
>>>> used in the Pseudowire Type AVP and Pseudowire
>
>>>>Capabilities List AVP
> >>>>
>
>>>>See also the registry "L2TPv3 Pseudowire Types" in
>
>>>>
http://www.iana.org/assignments/l2tp-parameters> >>>>
>
>>>>Regards,
> >>>>
>
>>>>--Carlos.
> >>>
> >>>[Sasha] What
are the reasons for keeping two different
> >>>name spaces for
the same set of objects (PW Types)?
> >>>Just the different
description of the format (2 octets
> >>>vs. 15-bit)? IMO it just
adds unnecessary complexity.
> >>
> >>They are arguably
two different sets of objects. RFC3931 defines the
> >>"L2TPv3
Pseudowire Type" (Section 10.6) as "a 2-octet value
> >>used in
the
> >>Pseudowire Type AVP and Pseudowire Capabilities List AVP";
OTOH,
> >>although the reference [1] is missing in
>
>>draft-ietf-pwe3-iana-allocation-09, it defines "Pseudowire
>
>>Type" values
> >>to be used with
draft-ietf-pwe3-control-protocol.
> >>The two spaces have different
allocation policy as well.
> >>Why is it this way? I suppose the
reasons are mostly historical, and
> >>while it may add complexity,
it also keeps separation and
> >>adds flexibility.
>
>>
> >>
> >>>E.g., consider the case of
multi-segment PWs where
> >>>L2TPv3 segments must be stitched to
MPLS segments with
> >>>the appropriate interworking of both data
path and the
> >>
> >>control plane...
>
>>
> >>In this case, the IWF should also contemplate the
"L2TPv3 Pseudowire
> >>Type" <-> "Pseudowire Type" mapping, as
another object to interwork.
> >>
> >>
>
>>>The fact that no L2TP PW values have been allocated yet
>
>>
> >>(I've checked
> >>
> >>>the
registry before writing this email!) speaks for itself.
> >>
>
>>RFC3931 defines the number space but not the values. From
RFC3931:
> >> Defined PW types that
may appear in this list are
> >>managed by IANA
>
>> and will appear in associated
pseudowire-specific
> documents for
>
>> each PW type.
> >>...
>
>> There are no specific pseudowire types
>
>> assigned within this document. Each
pseudowire-specific document
> >> must allocate its own
PW types from IANA as necessary.
> >>
> >>And values are
suggested in the respective companion documents:
>
>>draft-ietf-l2tpext-pwe3-fr-05.txt
>
>>draft-ietf-l2tpext-pwe3-hdlc-05.txt
>
>>draft-ietf-l2tpext-pwe3-ethernet-03.txt
>
>>draft-ietf-l2tpext-pwe3-atm-03.txt
>
>>draft-ieft-l2tpext-tdm-00.txt
> >>
> >>The
allocation of suggested values for "L2TPv3 Pseudowire Type"
>
>>(included in those documents) was requested from IANA
> months
ago. The
> >>fact the values do not appear in the registry may be
just
> saying that
> >>there is a slow response from
IANA.
> >>
> >>Best Regards,
> >>
>
>>--Carlos.
> >>
> >>
> >>>...
snipped to the end ...
> >>>
> >>>
>
>>>
> >>>
> >>>... snipped to the end
...
> >>>
>
>>>_______________________________________________
>
>>>pwe3 mailing list
> >>>pwe3 <at> ietf.org
>
>>>
https://www1.ietf.org/mailman/listinfo/pwe3> >>>
>
>>
> >>--
> >>--Carlos.
> >>Escalation
RTP - cisco Systems
> >>
> >
> >
>
>
--
> --Carlos.
> Escalation RTP - cisco Systems
>