Re: Methods to label the passive interfaces within ISIS

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Hi Tony,

I agree with you that essentially this is a link property (hence my earlier
hint towards 5029) so it makes it at least two of us recommending direction
towards 5029 now ;)

While we are at this perhaps it would be also useful to be able to
differentiate reachability on stub links vs virtual local interfaces. Today
in some implementations they are advertised after marking them as passive
int.

Thx
R.


On Fri, Jan 10, 2020, 08:26 <[email protected]> wrote:

>
> Hi Aijun,
>
>
> For the link attributes that defined in RFC5029, as that stated in
> https://tools.ietf.org/html/rfc5029#section-2, this sub-TLV is included
> in the TLV 22(Extended IS Reachability).
> As I read the IANA code point
> https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.=
xhtml#isis-tlv-codepoints-22-23-25-141-222-223
> , it notes this sub-TLV can be included in all of these TLVs
> (22,23,25,141,222,223).
>
> But, when the interface is configured as passive/stub, it seems that the
> above TLVs will not be advertised, because there is no IS neighbor on thi=
s
> passive link.
>
>
>
> Fair point. Given that there is an IP address and prefix on that link, it
> would be very reasonable to advertise the Extended IP Reachability TLV
> (135). We would then need to make the link attributes sub-TLV applicable =
to
> this TLV (and it=E2=80=99s MT brother).
>
>
> TLV 141 =E2=80=9CInter-AS reachability information=E2=80=9D seems be one =
appropriate TLV
> to include this sub-TLV, but it requires the IS-IS TE deployment, and is
> not suitable for describing the passive/stub link on edge router.
>
> In summary, it seems put this attribute into the =E2=80=9CPrefix Attribut=
e Flags=E2=80=9D
> sub-TLV which can be included in TLV 135,235,236 and 237 (Extended IP
> reachability, MT IP. Reach, IPv6 IP. Reach, and MT IPv6 IP. Reach TLVs) i=
s
> more applicable?
>
>
>
> It would seem to me that what you=E2=80=99re describing is an attribute o=
f a link,
> not of a prefix, thus I would favor it remaining a link attribute.
>
> But that=E2=80=99s just me.  :-)
>
> Tony
>
>

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<div dir=3D"auto"><div>Hi Tony,<div dir=3D"auto"><br></div><div dir=3D"auto=
">I agree with you that essentially this is a link property (hence my earli=
er hint towards 5029) so it makes it at least two of us recommending direct=
ion towards 5029 now ;)</div><div dir=3D"auto"><br></div><div dir=3D"auto">=
While we are at this perhaps it would be also useful to be able to differen=
tiate reachability on stub links vs virtual local interfaces. Today in some=
 implementations they are advertised after marking them as passive int.</di=
v><div dir=3D"auto"><br></div><div dir=3D"auto">Thx</div><div dir=3D"auto">=
R.</div><br><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_=
attr">On Fri, Jan 10, 2020, 08:26  &lt;<a href=3D"mailto:[email protected]">t=
[email protected]</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" st=
yle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div =
style=3D"word-wrap:break-word;line-break:after-white-space"><div><br></div>=
Hi Aijun,<div><br></div><div><br><div><blockquote type=3D"cite"><div><div s=
tyle=3D"font-family:Helvetica;font-size:14px;font-style:normal;font-variant=
-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text=
-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-de=
coration:none"><div style=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-fa=
mily:=E5=AE=8B=E4=BD=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;fon=
t-family:Calibri,sans-serif;color:rgb(31,73,125)">For the link attributes t=
hat defined in RFC5029, as that stated in<span>=C2=A0</span></span><span la=
ng=3D"EN-US"><a href=3D"https://tools.ietf.org/html/rfc5029#section-2" styl=
e=3D"color:purple;text-decoration:underline" target=3D"_blank" rel=3D"noref=
errer">https://tools.ietf.org/html/rfc5029#section-2</a>,<span>=C2=A0</span=
></span><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,=
sans-serif;color:rgb(31,73,125)">this sub-TLV is included in the TLV 22(Ext=
ended IS Reachability).<span>=C2=A0</span><u></u><u></u></span></div><div s=
tyle=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=8B=E4=BD=
=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,san=
s-serif;color:rgb(31,73,125)">As I read the IANA code point<span>=C2=A0</sp=
an></span><span lang=3D"EN-US"><a href=3D"https://www.iana.org/assignments/=
isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-22-23-25-=
141-222-223" style=3D"color:purple;text-decoration:underline" target=3D"_bl=
ank" rel=3D"noreferrer">https://www.iana.org/assignments/isis-tlv-codepoint=
s/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-22-23-25-141-222-223</a><sp=
an style=3D"color:rgb(31,73,125)">,<span>=C2=A0</span></span></span><span l=
ang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,sans-serif;colo=
r:rgb(31,73,125)">it notes this sub-TLV can be included in all of these TLV=
s (22,23,25,141,222,223).<span>=C2=A0</span><u></u><u></u></span></div><div=
 style=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=8B=E4=
=BD=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,=
sans-serif;color:rgb(31,73,125)"><u></u>=C2=A0<u></u></span></div><div styl=
e=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=8B=E4=BD=93"=
><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,sans-se=
rif;color:rgb(31,73,125)">But, when the interface is configured as passive/=
stub, it seems that the above TLVs will not be advertised, because there is=
 no IS neighbor on this passive link.=C2=A0<span>=C2=A0</span></span></div>=
</div></div></blockquote><div><br></div><div><br></div><div>Fair point. Giv=
en that there is an IP address and prefix on that link, it would be very re=
asonable to advertise the Extended IP Reachability TLV (135). We would then=
 need to make the link attributes sub-TLV applicable to this TLV (and it=E2=
=80=99s MT brother).</div><div><br></div><br><blockquote type=3D"cite"><div=
 style=3D"font-family:Helvetica;font-size:14px;font-style:normal;font-varia=
nt-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;te=
xt-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-=
decoration:none"><div style=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-=
family:=E5=AE=8B=E4=BD=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;f=
ont-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></=
div><div style=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=
=8B=E4=BD=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Ca=
libri,sans-serif;color:rgb(31,73,125)">TLV 141 =E2=80=9CInter-AS reachabili=
ty information=E2=80=9D seems be one appropriate TLV to include this sub-TL=
V, but it requires the IS-IS TE deployment, and is not suitable for describ=
ing the passive/stub link on edge router.<u></u><u></u></span></div><div st=
yle=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=8B=E4=BD=
=93"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,san=
s-serif;color:rgb(31,73,125)"><u></u>=C2=A0<u></u></span></div><div style=
=3D"margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:=E5=AE=8B=E4=BD=93">=
<span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Calibri,sans-ser=
if;color:rgb(31,73,125)">In summary, it seems put this attribute into the =
=E2=80=9CPrefix Attribute Flags=E2=80=9D sub-TLV which can be included in T=
LV 135,235,236 and 237 (Extended IP reachability, MT IP. Reach, IPv6 IP. Re=
ach, and MT IPv6 IP. Reach TLVs) is more applicable?</span></div></div></bl=
ockquote><br></div></div><div><br></div><div>It would seem to me that what =
you=E2=80=99re describing is an attribute of a link, not of a prefix, thus =
I would favor it remaining a link attribute.</div><div><br></div><div>But t=
hat=E2=80=99s just me. =C2=A0:-)</div><div><br></div><div>Tony</div><div><b=
r></div></div></blockquote></div></div></div>

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