Re: Narrow/Wide ISIS metrics

From: Shankar Vemulapalli (svemulap@cisco.com)
Date: Fri Jun 08 2001 - 15:16:51 EDT


As you see below from the database - this router is receiving two types
of TLVs (both TLV 128 and TLV 135) - and interpreting it the right way.
i.e., this router is listening to both of them -

For ex.: IP Prefix 10.0.56.4 is been received via both the TLVs.

All the above is based on the info. you put in below -
Caputed on R2 for R1's databse - most likely R2 is narrow-only but R1
is configured to listen to both !

Also, I have just now verified in the lab and it works !

Btw - there were some caveats with the older rev. of code.
(the reason is that at that time - the drafts are yet to get finalized)
So, please make sure you have the recent rev. of code.

Hope it helps,

/Shankar

! From j.belcina@computer.org Fri Jun 8 10:06:14 2001
!
! Hi Shankar,
!
! But what should be the correct behaviour when a "narrow-only" router
! receives TLV135?
!
! Even more unclear is that, not only did the "narrow-only" router listened
! to TLV135, the metrics of TLV128 are incremented by 64 than than the
! metrics of TLV135, as below:
!
! R2>sh isis data detail
! IS-IS Level-1 Link State Database
! LSPID LSP Seq Num LSP Checksum LSP Holdtime
! ATT/P/OL
! R1.00-00 0x00037A52 0x3502 331 1/0/0
! Area Address: 47.0002
! NLPID: 0xCC
! Router ID: 10.0.56.4
! IP Address: 10.0.56.4
! Hostname: R1
! Metric: 2 IS R2.00
! Metric: 2 IS-Extended R2.00
! Metric: 0 IP 10.0.56.4 255.255.255.255
! Metric: 2 IP 10.0.56.76 255.255.255.252
! Metric: 2 IP 10.0.56.80 255.255.255.252
! Metric: 68 IP 10.0.56.32 255.255.255.252
! Metric: 70 IP 10.0.56.36 255.255.255.252
! Metric: 80 IP 10.0.56.56 255.255.255.252
! Metric: 80 IP 10.1.1.0 255.255.255.0
! Metric: 0 IP 10.0.56.4/32
! Metric: 2 IP 10.0.56.76/30
! Metric: 2 IP 10.0.56.80/30
! Metric: 4 IP-Interarea 10.0.56.32/30
! Metric: 6 IP-Interarea 10.0.56.36/30
! Metric: 16 IP-Interarea 10.0.56.56/30
! Metric: 16 IP-Interarea 10.1.1.0/24
!
! Thanks.
! J.B.
!
!
! On Thu, 7 Jun 2001, Shankar Vemulapalli wrote:
!
! > J.B.:
! >
! >
! > The default behavior is to generate narrow metrics.
! > In this mode the router will accept and generate only narrow-style
! > metrics - (TLV 128).
! >
! > You can configure a router to generate wide-style metrics.
! > In this mode the router will accept and generate only wide-style
! > metrics - (TLV 135).
! >
! > When you have routers in your network which can understand either
! > narrow-only or wide-only, to interoperate between them - you can
! > configure the router(s) for 'transition' mode.
! >
! > In this mode based on whether it is 'narrow transition' or
! > 'wide transition', the router will accept narrow and wide and generate
! > narrow only or vice versa.
! >
! > The 'transition' mode is recommended to be used only during the
! > transition phase of the routers from narrow to wide.
! >
! > You can look at the 'show clns protocol' command to figure out what
! > kind of ISIS metric style that the router is generating/accepting.
! >
! > Hope it helps,
! >
! >
! >
! > /Shankar
! >
! > ! Date: Thu, 7 Jun 2001 03:28:56 -0400
! > ! From: j.belcina@computer.org
! > ! Subject: Narrow/Wide ISIS metrics
! > !
! > !
! > ! Does anyone know what's the behaviour of a Cisco router,
! > ! set to default (generate narrow metrics only), when it receives both types
! > ! of TLVs for the same prefix?
! > !
! > ! Thanks.
! > ! J.B.
! > !
! > !
! >
!
!



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