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<div class="moz-cite-prefix">On 17/Jun/20 19:38, Saku Ytti wrote:<br>
<br>
</div>
<blockquote type="cite"
cite="mid:CAAeewD8Y3wP4WgtSAnPcdJdOKqSeZkzD0BceDMJPqtNUEiTebQ@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">I don't like this, SR-MPLS and SRv6 are just utterly different things
to me, and no answer meaningfully applies to both.</pre>
</blockquote>
<br>
I know they are different, but that was on purpose, because even
with SR-MPLS, there are a couple of things to consider:<br>
<ul>
<li>IOS XR does not appear to support SR-OSPFv3.</li>
<li>IOS XE does not appear to support SR-ISISv6.</li>
<li>IOS XE does not appear to support SR-OSPFv3.</li>
<li>Junos does not appear to support SR-OSPFv3.</li>
<li>MPLS/VPN service signaling in IPv6-only networks also has gaps
in SR.<br>
</li>
</ul>
<p>So for networks that run OSPF and don't run Juniper, they'd need
to move to IS-IS in order to have SR forward IPv6 traffic in an
MPLS encapsulation. Seems like a bit of an ask. Yes, code needs to
be written, which is fine by me, as it also does for LDPv6.</p>
<p><br>
</p>
<p>
</p>
<blockquote type="cite"
cite="mid:CAAeewD8Y3wP4WgtSAnPcdJdOKqSeZkzD0BceDMJPqtNUEiTebQ@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">I would ask, why do we need LDP, why not use IGP to carry labels?
Less state, protocols, SLOC, cost, bug surface</pre>
</blockquote>
<br>
I'd be curious to understand what bugs you've suffered with LDP in
the last 10 or so years, that likely still have open tickets.<br>
<br>
Yes, we all love less state, I won't argue that. But it's the same
question that is being asked less and less with each passing year -
what scales better in 2020, OSPF or IS-IS. That is becoming less
relevant as control planes keep getting faster and cheaper.<br>
<br>
I'm not saying that if you are dealing with 100,000 T-LDP sessions
you should not consider SR, but if you're not, and SR still requires
a bit more development (never mind deployment experience), what's
wrong with having LDPv6? If it makes near-as-no-difference to your
control plane in 2020 or 2030 as to whether your 10,000-node network
is running LDP or SR, why not have the choice?<br>
<br>
<br>
<blockquote type="cite"
cite="mid:CAAeewD8Y3wP4WgtSAnPcdJdOKqSeZkzD0BceDMJPqtNUEiTebQ@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">
And we get more features to boot, with LDP if you want LFA, you need
to form tLDP to every Q-space node, on top of your normal LDP, because
you don't know label view from anyone else but yourself. With SR by
nature you know the label view for everyone, thus you have full LFA
coverage for free, by-design.
Also by-design IGP/LDP Sync.
So no need to justify it by any magic new things, it's just a lot
simpler than LDP, you don't need to need new things to justify
SR-MPLS, you need to want to do existing things while reducing
complexity and state.</pre>
</blockquote>
<br>
Again, it's a question of scale and requirements. Some large
networks don't run any RSVP, while some small networks do.<br>
<br>
I'm not saying let's not do SR; but for those who want something
mature, and for those who want something new, I don't see a reason
why the choice can't be left up to the operator.<br>
<br>
Routers, in 2020, still ship with RIPv2. If anyone wants to use it
(as I am sure there are some that do), who are we to stand in their
way, if it makes sense for them?<br>
<br>
Mark.<br>
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