[c-nsp] Question on ISIS Cisco

[Jay Ford]

On Thu, 4 Aug 2011, Olivier CALVANO wrote:
> I'm looking for information on configuring ISIS
> on cisco 6500/Sup720-3BXL:
>
> I have two Cisco 6500/Sup720-3BXL connected by
> Layer 2 link of 1 Gbit.
>
> My config:
>
> C6500-1:
>
> interface GigabitEthernet1/2
> mtu 2000
> ip address 192.168.100.1 255.255.255.252
> ip router isis
> speed nonegotiate
> mpls label protocol ldp
> tag-switching ip
> clns mtu 1500
>
> router isis
> net 49.0001.0000.0000.0424.00
> is-type level-2-only
> metric-style wide
> redistribute connected
>
>
>
>
> C6500-2:
>
> interface GigabitEthernet3/2
> mtu 2000
> ip address 192.168.100.2 255.255.255.252
> ip router isis
> speed nonegotiate
> mpls label protocol ldp
> mpls ip
>
> router isis
> net 49.0001.0000.0000.0421.00
> is-type level-2-only
> metric-style wide
> redistribute connected
> !
>
>
>
>
> Soon, I will add a new link between the two for backup.
> This link is on port Gigabit but there are only 100 Mbits of Commit
> I would like the cisco C6500 use it only on the 1 Gb link does not work
> more.
>
> I will add in config:
>
> C6500-1:
>
> interface GigabitEthernet1/3
> mtu 2000
> ip address 192.168.50.1 255.255.255.252
> ip router isis
> speed nonegotiate
> mpls label protocol ldp
> tag-switching ip
> clns mtu 1500
>
>
> C6500-2:
>
> interface GigabitEthernet3/3
> mtu 2000
> ip address 192.168.50.2 255.255.255.252
> ip router isis
> speed nonegotiate
> mpls label protocol ldp
> mpls ip
>
>
> How can I do to make it a priority is having an link compared to another?

Set ISIS metrics on the interfaces.  Lower numbers are favored.  For example,
to favor the first link:
    C6500-1:
       interface GigabitEthernet1/2
        isis metric 100
       interface GigabitEthernet1/3
        isis metric 200
    C6500-2:
       interface GigabitEthernet3/2
        isis metric 100
       interface GigabitEthernet3/3
        isis metric 200

Pay attention to how your metrics interact on your various links.  The "show
isis topology" command should show the existing interface metrics.

Note that metrics can be (& perhaps must be) configured distinctly for IPv4 &
IPv6.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford at uiowa.edu, phone: 319-335-5555, fax: 319-335-2951