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Subject: [Lsr] =?utf-8?b?562U5aSNOiAgIOetlOWkjTogIOetlOWkjTog562U5aSNOiBS?= =?utf-8?q?egarding_OSPF_extension
From: "Aijun Wang" <wangaijun () tsinghua ! org ! cn>
Date: 2018-07-25 3:50:16
Message-ID: 005c01d423ca$99c382c0$cd4a8840$ () org ! cn
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Hi, Rob:
If we use BGP-LS to get the underlay topology, we will not consider deployment other \
methods such as IGP adjacency or LSDB telemetry, although all of them are applicable.
If we deploy BGP-LS adjacency with routers in multi-area to get the full multi-area \
topology, it will be no different with the traditional IGP adjacency, increase the \
complexity that BGP-LS solution itself can reduce.
On the other hand, if we do not solve such scenario, isn't BGP-LS one complete \
solution for underlay IGP topology gathering?
Best Regards.
Aijun Wang
Network R&D and Operation Support Department
China Telecom Corporation Limited Beijing Research Institute,Beijing, China.
发件人: Rob Shakir [mailto:rjs@rob.sh]
发送时间: 2018年7月25日 0:22
收件人: Aijun Wang
抄送: Dongjie (Jimmy); chopps@chopps.org; Peter Psenak; Ketan Talaulikar (ketant); \
lsr@ietf.org; Acee Lindem (acee) 主题: Re: [Lsr] 答复: 答复: 答复: Regarding \
OSPF extension for inter-area topology retrieval
On 23 July 2018 at 23:37, Aijun Wang <wangaijun@tsinghua.org.cn> wrote:
To Rob:
BGP-LS is one prominent method to get the underlay network topology and has more \
flexibility to control the topology export as described in RFC 7752 \
<https://tools.ietf.org/html/rfc7752#section-1> .
Solution 1) that you proposed is possible, but we will not run two different methods \
to get the topology.
What is the other method that you're running alongside an IGP adjacency? This is a \
single method that just uses the IGP protocol that you have today.
Solution 2) is also one possible deployment, but it eliminates the advantage of the \
BGP-LS, in which it needs several interaction points with the underlay network. and \
such deployment is not belong to redundancy category as information got from \
different areaes are different.
Yes, the information is different but this is why you have areas within the IGP. Are \
you implying that your controller cannot merge topologies from different areas? I'd \
suggest that this is something that is relatively trivial to add into that code, \
rather than changing the code running on your routers.
Solution 3)--Streaming telemetry technology should be used mainly for the monitor of \
network devices, it requires the PCE controller to contact with every router in the \
network, is also not the optimal solution when compared with BGP-LS.
This is not true. LSDB export via streaming telemetry (for the entire LSDB) is \
possible in today's running code with IS-IS, and models are written for OSPF's LSDB. \
The controller just needs to interact with one device per area per the existing \
discussion.
Assertion that this is not the optimal solution seems more like opinion to me. Some \
justification would be useful for us to understand why the existing solutions that \
are shipping aren't suitable. Why should we further complicate protocols that ship \
for everyone if there is no technical reason to do so?
We can update the current draft to include all possible scenarios that we are not \
aiming at beginning for integrity consideration. The proposed extension does not add \
to complexity of IGP. What we discussed here is the complexity of IGP protocol \
itself.
You're asking for information that is explicitly partitioned (based on the fact that \
your network is partitioned into areas) to be exported into an area simply to reduce \
the number of adjacencies between a controller and the network to N (where N is the \
redundancy of the controller) rather than N*areas -- why is this the right trade-off?
r.
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class=WordSection1><p class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi, \
Rob:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p \
class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>If we use \
BGP-LS to get the underlay topology, we will not consider deployment other methods \
such as IGP adjacency or LSDB telemetry, although all of them are \
applicable.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>If we \
deploy BGP-LS adjacency with routers in multi-area to get the full multi-area \
topology, it will be no different with the traditional IGP adjacency, increase the \
complexity that BGP-LS solution itself can reduce.<o:p></o:p></span></p><p \
class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p \
class=MsoNormal><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>On the \
other hand, if we do not solve such scenario, isn't BGP-LS one complete solution for \
underlay IGP topology gathering?<o:p></o:p></span></p><p class=MsoNormal><span \
lang=EN-US style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p \
class=MsoNormal style='text-align:justify;text-justify:inter-ideograph'><span \
lang=EN-US style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>Best \
Regards.<o:p></o:p></span></p><p class=MsoNormal \
style='text-align:justify;text-justify:inter-ideograph'><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p \
class=MsoNormal style='text-align:justify;text-justify:inter-ideograph'><span \
lang=EN-US style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>Aijun \
Wang<o:p></o:p></span></p><p class=MsoNormal \
style='text-align:justify;text-justify:inter-ideograph'><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>Network \
R&D and Operation Support Department<o:p></o:p></span></p><p class=MsoNormal \
style='text-align:justify;text-justify:inter-ideograph'><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>China \
Telecom Corporation Limited Beijing Research Institute,Beijing, \
China.<o:p></o:p></span></p><div style='border:none;border-top:solid #B5C4DF \
1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span \
style='font-size:10.0pt'>发件人<span lang=EN-US>:</span></span></b><span \
lang=EN-US style='font-size:10.0pt'> Rob Shakir [mailto:rjs@rob.sh] \
<br></span><b><span style='font-size:10.0pt'>发送时间<span \
lang=EN-US>:</span></span></b><span lang=EN-US style='font-size:10.0pt'> \
2018</span><span style='font-size:10.0pt'>年<span lang=EN-US>7</span>月<span \
lang=EN-US>25</span>日<span lang=EN-US> 0:22<br></span><b>收件人<span \
lang=EN-US>:</span></b><span lang=EN-US> Aijun Wang<br></span><b>抄送<span \
lang=EN-US>:</span></b><span lang=EN-US> Dongjie (Jimmy); chopps@chopps.org; Peter \
Psenak; Ketan Talaulikar (ketant); lsr@ietf.org; Acee Lindem \
(acee)<br></span><b>主题<span lang=EN-US>:</span></b><span lang=EN-US> Re: [Lsr] \
</span>答复<span lang=EN-US>: </span>答复<span lang=EN-US>: </span>答复<span \
lang=EN-US>: Regarding OSPF extension for inter-area topology \
retrieval<o:p></o:p></span></span></p></div><p class=MsoNormal><span \
lang=EN-US><o:p> </o:p></span></p><div><p class=MsoNormal><span \
lang=EN-US><o:p> </o:p></span></p><div><p class=MsoNormal><span \
lang=EN-US><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-US>On 23 \
July 2018 at 23:37, Aijun Wang <<a href="mailto:wangaijun@tsinghua.org.cn" \
target="_blank">wangaijun@tsinghua.org.cn</a>> \
wrote:<o:p></o:p></span></p><div><div><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'> </span><span \
lang=EN-US><o:p></o:p></span></p><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><u><span lang=EN-US \
style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D'>To Rob: \
</span></u><span lang=EN-US><o:p></o:p></span></p><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'> </span><span \
lang=EN-US><o:p></o:p></span></p><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'>BGP-LS is one prominent method to get the \
underlay network topology and has more flexibility to control the topology export as \
described in <a href="https://tools.ietf.org/html/rfc7752#section-1" \
target="_blank">RFC 7752</a>. </span><span lang=EN-US><o:p></o:p></span></p><p \
class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span \
lang=EN-US style='font-size:10.0pt;color:black'> </span><span \
lang=EN-US><o:p></o:p></span></p><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'>Solution 1) that you proposed is possible, but \
we will not run two different methods to get the topology.</span><span \
lang=EN-US><o:p></o:p></span></p></div></div><div><p class=MsoNormal><span \
lang=EN-US><o:p> </o:p></span></p></div><div><p class=MsoNormal><span \
lang=EN-US>What is the other method that you're running alongside an IGP adjacency? \
This is a single method that just uses the IGP protocol that you have \
today.<o:p></o:p></span></p></div><div><p class=MsoNormal><span \
lang=EN-US> <o:p></o:p></span></p></div><blockquote \
style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm \
6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'>Solution 2) is also one possible deployment, but \
it eliminates the advantage of the BGP-LS, in which it needs several interaction \
points with the underlay network. and such deployment is not belong to redundancy \
category as information got from different areaes are different.</span><span \
lang=EN-US><o:p></o:p></span></p></div></div></blockquote><div><p \
class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p \
class=MsoNormal><span lang=EN-US>Yes, the information is different but this is why \
you have areas within the IGP. Are you implying that your controller cannot merge \
topologies from different areas? I'd suggest that this is something that is \
relatively trivial to add into that code, rather than changing the code running on \
your routers.<o:p></o:p></span></p></div><div><p class=MsoNormal><span \
lang=EN-US> <o:p></o:p></span></p></div><blockquote \
style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm \
6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'>Solution 3)--Streaming telemetry technology \
should be used mainly for the monitor of network devices, it requires the PCE \
controller to contact with every router in the network, is also not the optimal \
solution when compared with BGP-LS.</span><span \
lang=EN-US><o:p></o:p></span></p></div></div></blockquote><div><p \
class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p \
class=MsoNormal><span lang=EN-US>This is not true. LSDB export via streaming \
telemetry (for the entire LSDB) is possible in today's running code with IS-IS, and \
models are written for OSPF's LSDB. The controller just needs to interact with one \
device per area per the existing discussion. <o:p></o:p></span></p></div><div><p \
class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p \
class=MsoNormal><span lang=EN-US>Assertion that this is not the optimal solution \
seems more like opinion to me. Some justification would be useful for us to \
understand why the existing solutions that are shipping aren't suitable. Why should \
we further complicate protocols that ship for everyone if there is no technical \
reason to do so?<o:p></o:p></span></p></div><div><p class=MsoNormal><span \
lang=EN-US> <o:p></o:p></span></p></div><blockquote \
style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm \
6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal \
style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US \
style='font-size:10.0pt;color:black'> We can update the current draft to include \
all possible scenarios that we are not aiming at beginning for integrity \
consideration. The proposed extension does not add to complexity of IGP. What we \
discussed here is the complexity of IGP protocol itself.</span><span \
lang=EN-US><o:p></o:p></span></p></div></div></blockquote><div><p \
class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p \
class=MsoNormal><span lang=EN-US style='color:black'> You're asking for \
information that is explicitly partitioned (based on the fact that your network is \
partitioned into areas) to be exported into an area simply to reduce the number of \
adjacencies between a controller and the network to N (where N is the redundancy of \
the controller) rather than N*areas -- why is this the right trade-off?</span><span \
lang=EN-US><o:p></o:p></span></p></div><div><p class=MsoNormal><span \
lang=EN-US><o:p> </o:p></span></p></div><div><p class=MsoNormal><span lang=EN-US \
style='color:black'>r.</span><span \
lang=EN-US><o:p></o:p></span></p></div></div></div></div></div></body></html>
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