Mailing List Archive: show isis neighbors - system id shown

show isis neighbors - system id shown

Feb 2, 2020, 7:22 AM

Post #1 of 6 (1234 views)

funny, for a moment there it actually displayed the sys id of r1 instead of
the word "r1"

is there a reason why ?

r2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

1111.1111.1111 L1 Fa0/0 1.2.3.1 UP 23 r2.01

1111.1111.1111 L2 Fa0/0 1.2.3.1 UP 24 r2.01

r2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

r1 L1 Fa0/0 1.2.3.1 UP 27 r2.01

r1 L2 Fa0/0 1.2.3.1 UP 28 r2.01

r2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

r1 L1 Fa0/0 1.2.3.1 UP 23 r2.01

r1 L2 Fa0/0 1.2.3.1 UP 24 r2.01

r2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

r1 L1 Fa0/0 1.2.3.1 UP 22 r2.01

r1 L2 Fa0/0 1.2.3.1 UP 23 r2.01

r2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

r1 L1 Fa0/0 1.2.3.1 UP 21 r2.01

r1 L2 Fa0/0 1.2.3.1 UP 22 r2.01

r2#

-Aaron

_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Re: show isis neighbors - system id shown [ In reply to ]

robert at raszuk

Feb 2, 2020, 7:42 AM

Post #2 of 6 (1234 views)

> is there a reason why ?

Looks to me like you are pretty fast in repetitive show commands :)

What actually may be happening here is that adj. comes up fast and at this
point your router does not yet have the dynamic name. After some time it
receives it from the neighbor via flooding in TLV 137 and then creates a
mapping hence in subsequent commands you see the name.

Works as designed :) Flooding that TLV may take a bit of time as well as
your local system may not treat it as top important info.

Ref: Original Henk's RFC 2763 later replaced by RFC 5301

Best,
R.

On Sun, Feb 2, 2020 at 4:22 PM Aaron Gould <aaron1@gvtc.com> wrote:

> funny, for a moment there it actually displayed the sys id of r1 instead of
> the word "r1"
>
>
>
> is there a reason why ?
>
>
>
> r2#sh isis neighbors
>
>
>
> System Id Type Interface IP Address State Holdtime Circuit Id
>
> 1111.1111.1111 L1 Fa0/0 1.2.3.1 UP 23 r2.01
>
> 1111.1111.1111 L2 Fa0/0 1.2.3.1 UP 24 r2.01
>
>
>
> r2#sh isis neighbors
>
>
>
> System Id Type Interface IP Address State Holdtime Circuit Id
>
> r1 L1 Fa0/0 1.2.3.1 UP 27 r2.01
>
> r1 L2 Fa0/0 1.2.3.1 UP 28 r2.01
>
> r2#sh isis neighbors
>
>
>
> System Id Type Interface IP Address State Holdtime Circuit Id
>
> r1 L1 Fa0/0 1.2.3.1 UP 23 r2.01
>
> r1 L2 Fa0/0 1.2.3.1 UP 24 r2.01
>
> r2#sh isis neighbors
>
>
>
> System Id Type Interface IP Address State Holdtime Circuit Id
>
> r1 L1 Fa0/0 1.2.3.1 UP 22 r2.01
>
> r1 L2 Fa0/0 1.2.3.1 UP 23 r2.01
>
> r2#sh isis neighbors
>
>
>
> System Id Type Interface IP Address State Holdtime Circuit Id
>
> r1 L1 Fa0/0 1.2.3.1 UP 21 r2.01
>
> r1 L2 Fa0/0 1.2.3.1 UP 22 r2.01
>
> r2#
>
>
>
> -Aaron
>
>
>
> _______________________________________________
> cisco-nsp mailing list cisco-nsp@puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Re: show isis neighbors - system id shown [ In reply to ]

mark.tinka at seacom

Feb 2, 2020, 7:49 AM

Post #3 of 6 (1234 views)

On 2/Feb/20 17:22, Aaron Gould wrote:

> funny, for a moment there it actually displayed the sys id of r1 instead of
> the word "r1"
>
>
>
> is there a reason why ?

Pretty normal when the adjacency comes up for the first time. A few
moments later as everything settles down, the System ID's map back to
the remote router's hostname.

Mark.
_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Re: show isis neighbors - system id shown [ In reply to ]

sthaug at nethelp

Feb 2, 2020, 7:51 AM

Post #4 of 6 (1234 views)

>> is there a reason why ?
>
> Looks to me like you are pretty fast in repetitive show commands :)
>
> What actually may be happening here is that adj. comes up fast and at this
> point your router does not yet have the dynamic name. After some time it
> receives it from the neighbor via flooding in TLV 137 and then creates a
> mapping hence in subsequent commands you see the name.
>
> Works as designed :) Flooding that TLV may take a bit of time as well as
> your local system may not treat it as top important info.

I've seen the same thing multiple times on Juniper and Huawei routers.
I agree, this is working as intended.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no
_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Re: show isis neighbors - system id shown [ In reply to ]

Feb 2, 2020, 7:59 AM

Post #5 of 6 (1234 views)

Thanks y'all

-Aaron

_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Re: show isis neighbors - system id shown [ In reply to ]

Feb 2, 2020, 9:20 AM

Post #6 of 6 (1234 views)

On Sun, 2 Feb 2020 at 17:22, Aaron Gould <aaron1@gvtc.com> wrote:

> is there a reason why ?

I think you got a bunch of replies, but I'm not sure if the specific
reason was addressed. TLV137 is part of LSP PDU and the neighbour is
seen at one of the three possible Hello PDU, which does not yet
contain TLV137.

--
++ytti
_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/