Hi, Xian,
Thanks, please see my reply in-line.
Qilei Wang
"Zhangxian (Xian)" <zhang.x...@huawei.com>
2013-09-16 15:45
收件人
"wang.qi...@zte.com.cn" <wang.qi...@zte.com.cn>, Ramon Casellas
<ramon.casel...@cttc.es>,
抄送
"pce@ietf.org" <pce@ietf.org>
主题
RE: [Pce] A comment regarding domain diversity in
draft-ietf-pce-hierarchy-extensions
Hi, Qilei, Ramon and all,
I think Ramon provides a straightforward solution to this
requirement. But I would like to step back and ask: whether we should
specify the domain diversity in PCEP for H-PCE or not? As we can see not
all requirements specified in H-PCE RFC are accommodated in
draft-ietf-pce-hierarchy-extensions (e.g., Setion 1.1.).
[Qilei]: I can understand why the functions listed in section 1.1 are out
of the scope of this draft, maybe because of BGP-TE and/or interior
implementation. But I can't really know the reason why domain diversity
does not fit in PCEP for H-PCE. Can you offer me more reasons here? Or
maybe we can further discuss about this.
According to Section 1.3.2 in RFC6805, domain diversity can facilitate
path diversity. If this is the only reason, what currently defined in
RFC5440 accommodates this need already, right?
[Qilei]: How could the RFC5440 satisfy this need?
If the source node only wants path diversity but specify domain diversity,
it may end up with no path available, assume there is one transit domain
all paths will have to go through from the source domain. On the other
hand, if the source node only specifies path diversity, it may or may not
get a domain-diversified path, which can be decided by the parent PCE.
[Qilei]: I agree with your analysis. It may end up with no path available,
but it is still the computation result of the PCE. Just from my opinion,
we should firstly focus on the requirement whether we should specify the
domain diversity in PCEP for H-PCE or not, as you addressed at the
beginning.
Any thoughts?
Regards,
Xian
From: pce-boun...@ietf.org [mailto:pce-boun...@ietf.org] On Behalf Of
wang.qi...@zte.com.cn
Sent: 2013年9月13日 15:27
To: Ramon Casellas
Cc: pce@ietf.org
Subject: Re: [Pce] A comment regarding domain diversity in
draft-ietf-pce-hierarchy-extensions
Hi, Ramon,
Thank you for pointing the RFC6007 to me. I almost forgot this draft.
Yeah, you are right. This requirement can be satisfied by two approaches.
One is the 2-step approach which can be addressed by IRO/XRO, and the
other is the "D flag" in SVEC object in the H-PCE scenario according to
your mail.
Just from my opinion, the new flag indicating "domain diverse" in SVEC
object is needed in PCEP protocol.
Thanks
Qilei Wang
Ramon Casellas <ramon.casel...@cttc.es>
发件人: pce-boun...@ietf.org
2013-09-13 12:48
收件人
pce@ietf.org,
抄送
主题
Re: [Pce] A comment regarding domain diversity in
draft-ietf-pce-hierarchy-extensions
Just from my understanding, maybe this requirement can be resolved by
extending the PCEP object to indicate "domain-diverse" requirement when
PCE computes a pair of dependent path at the same time. When PCC sends
path request to child PCE, this requirement can be indicated in the path
request message, and child PCE can forward this requirement indication to
the parent PCE. Parent PCE has the topology information of domains, so it
is able to compute two domain-diverse paths.
Hi Qilei, all
Would, for example, a new bit in the SVEC saying "domain diverse" fulfill
such requirement? I was reading http://tools.ietf.org/html/rfc6007 sect
5.3 that discusses this. The two step can be addressed by IRO/XRO and the
common H-PCE case could use a D flag. Domain sub-objects are not
domain-specific
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |D|S|N|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request-ID-number #1 |
// //
| Request-ID-number #M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Thoughts?
thanks, R.
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