From: Brown, Patrick (NSOC-OCF} (PBrown4@chartercom.com)
Date: Mon Aug 04 2003 - 22:43:26 GMT-3
1)When running HCCP with N+1 redundancy, there was an IOS bug that would
take the "ip router isis" command off the cable interface upon switchover.
By putting the interface in passive mode and advertising it into ISIS that
way, you would not face this problem.
2) If you have a customer facing interface, where 20,000 subscribers attach
to this interface. For security and performance reasons you would not want
to send ISIS info onto that segment. But you still need to advetise this
interface to your IGP.
There are a bunch more reasons I'm sure!
Patrickb
-----Original Message-----
From: Snow, Tim
To: 'John Matijevic'; MMoniz; Brown, Patrick (NSOC-OCF}; 'Tomasz Szymanski
'; 'Brian Dennis '
Cc: ''Tim Fletcher' '; ccielab@groupstudy.com
Sent: 8/4/2003 8:22 PM
Subject: RE: ISIS passive interface
Let's say that you wanted to get the Subnet that your running on your
loopback into the ISIS domain but you don't want the router to waste
valuable cycles sending ISIS hellos on the interface then you could use
the
passive-int command.
On the other hand, if you put "ip router isis" it'll actively run isis
on
that interface and send hellos. Keep in mind that OSPF isn't 100% the
same
with regards to the passive-int.
Tim
-----Original Message-----
From: John Matijevic [mailto:matijevi@bellsouth.net]
Sent: Monday, August 04, 2003 8:32 PM
To: MMoniz; Brown, Patrick (NSOC-OCF}; 'Tomasz Szymanski '; 'Brian
Dennis '
Cc: ''Tim Fletcher' '; ccielab@groupstudy.com
Subject: Re: ISIS passive interface
Hello Team,
Could somebody provide an example of when you would want to put an
interface
in passive mode under ISIS? I have not run into this situation yet. I
was
not able to access the link below.
Sincerely,
Matijevic
----- Original Message -----
From: "MMoniz" <ccie2002@tampabay.rr.com>
To: "Brown, Patrick (NSOC-OCF}" <PBrown4@chartercom.com>; "'Tomasz
Szymanski
'" <tomasz.szymanski@trecom.pl>; "'Brian Dennis '" <brian@labforge.com>
Cc: "''Tim Fletcher' '" <tim@fletchmail.net>; <ccielab@groupstudy.com>
Sent: Monday, August 04, 2003 7:48 PM
Subject: RE: ISIS passive interface
> Interesting. I did not know this but it works. I still notice however
these
> nets are not
> redistributed as usual so they must be include in the connected
> redistribution for other
> protocols.
>
> Thanks Patrick
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Brown, Patrick (NSOC-OCF}
> Sent: Monday, August 04, 2003 6:45 PM
> To: 'Tomasz Szymanski '; 'Brian Dennis '
> Cc: ''Tim Fletcher' '; 'ccielab@groupstudy.com '
> Subject: RE: ISIS passive interface
>
>
> By putting the loopback interface in passive mode(passive interface
> loopback 0), it is automatically made apart of the ISIS routing
process.
> This is not the same for other routing protocols. You can do "ip
router
> isis" on interface to put the loopback into the ISIS process, but this
will
> waste alot of CPU processing. When putting the lo0 interface in
passive
mode
> under ISIS, you DO NOT need the "ip router isis" command on the
loopback 0
> to advertise into ISIS process.
> HTH
>
> Patrick
> -----Original Message-----
> From: Tomasz Szymanski
> To: Brian Dennis
> Cc: 'Tim Fletcher'; ccielab@groupstudy.com
> Sent: 8/4/2003 5:05 PM
> Subject: Re: ISIS passive interface
>
> Are you sure Brian?
> I don't see "ip router isis" on Loopback interface so it's not in
isis
>
> process.
>
>
> TS
>
> Brian Dennis wrote:
>
> >With IS-IS when you make the interface passive the router removes the
> >"ip router is-is" command from under the interface. So in your case
the
> >loopback is still being advertised via IS-IS.
> >
> >Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security)
> >brian@labforge.com
> >http://www.labforge.com
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> >Tim Fletcher
> >Sent: Wednesday, January 29, 2003 11:53 AM
> >To: ccielab@groupstudy.com
> >Subject: ISIS passive interface
> >
> >Hi all,
> >
>
>http://www.cisco.com/en/US/tech/tk472/tk474/technologies_configuration_
> e
> >xample09186a0080093f38.shtml
> >shows the following config:
> >
> >interface Loopback0
> >ip address 172.16.1.1 255.255.255.255
> >!--- Creates loopback interface and assigns
> >!--- IP address to interface Loopback0.
> >!
> >interface Ethernet0
> >ip address 172.16.12.1 255.255.255.0
> >ip router isis
> >
> >!--- Assigns IP address to interface Ethernet0
> >!--- and enables IS-IS for IP on the interface.
> >!
> >router isis
> >passive-interface Loopback0
> >net 49.0001.1720.1600.1001.00
> >!
> >!--- Enables the IS-IS process on the router,
> >!--- makes loopback interface passive
> >!--- (does not send IS-IS packets on interface),
> >!--- and assigns area and system ID to router.
> >
> >My question is why would you need the passive-interface Lo0 command
> >under
> >the ISIS config, when ISIS is not configured on Lo0? Isn't this
> >redundant?
> >
> >-Tim Fletcher
> >.
> >.
>
>
>
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