From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Apr 23 2004 - 16:42:28 GMT-3
Ken,
I far as I know, there are NOT any Gotcha's using the match interface. And,
your reaction to this method was the same as mine - this is a simpler, less
chance of error way of accomplishing this task. That's probably why I've
mentioned several times. I prefer simpler, less error prone ways of doing
things and by saying (or writing it several times I burish the idea into my
brain which often times resist assimilating new knowledge.
HTH
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "R&S Groupstudy"
<rsg@synergy-networking.co.uk>; "Ahmed Mustafa"
<ahmed.mustafa@sbcglobal.net>; <ccielab@groupstudy.com>
Sent: Friday, April 23, 2004 2:19 PM
Subject: RE: Passive interfaces in ISIS
> Tim,
>
> You are correct. One thing I would like to ask though is that you've
> mentioned one thing several times. When redistributing, you've
> mentioned you can just specify "match interface" to choose which
> interfaces to redistribute. I've never done this before, always opting
> to the "match ip address" statement instead.
>
> Your method (match interface) seems more logical and easier to work
> with. Eliminating even a single variable, such as correlating the
> interface with IP address, can save valuable headaches during lab time.
>
> My question is this: Is there anytime "match interface" will not work
> when redistributing connected interfaces? Or is this simply a matter of
> preference and either one should work for any application?
>
> I just don't want to introduce additional complications or "gotchas" I
> haven't seen before by changing my strategy two days before my lab. But
> if there are no well-known gotchas, I might resort due to this its
> simplicity.
>
> Any advice is appreciated. :)
>
> Kenneth E. Wygand
> Systems Engineer, Project Services
> CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
> Network+, A+
> Custom Computer Specialists, Inc.
> "The only unattainable goal is the one not attempted."
> -Anonymous
>
> -----Original Message-----
> From: ccie2be [mailto:ccie2be@nyc.rr.com]
> Sent: Friday, April 23, 2004 2:00 PM
> To: R&S Groupstudy; Kenneth Wygand; Ahmed Mustafa;
> ccielab@groupstudy.com
> Subject: Re: Passive interfaces in ISIS
>
> Guys,
>
> I think there's one more thing that has to be kept in mind from the
> point of
> view of the lab.
>
> If ISIS is on the lab, no doubt there will be a requirement for route
> redistribution. So, here's the thing to remember:
>
> Regardless of which method is used to have a local interface included as
> part of ISIS, when you do redist of ISIS into another protocol, by
> default,
> directly connected interfaces are NOT redist. Therefore, in addition to
> "redist isis <options>, you must also have a redist conn route-map where
> the
> route-map specifies which directly connected interfaces s/b included in
> the
> redist.
>
> I haven't tested this recently, so if I'm mistaken, please correct me.
>
> Tim
> ----- Original Message -----
> From: "R&S Groupstudy" <rsg@synergy-networking.co.uk>
> To: "Kenneth Wygand" <KWygand@customonline.com>; "Ahmed Mustafa"
> <ahmed.mustafa@sbcglobal.net>; <ccielab@groupstudy.com>
> Sent: Friday, April 23, 2004 9:35 AM
> Subject: RE: Passive interfaces in ISIS
>
>
> > Kenneth,
> >
> > I don't think this is correct.
> > If you've a loopback interface on a router - and you want this IP
> subnet
> to
> > be advertised to other routers you can do one of the following.
> > 1. Interface command, ip router isis
> > or
> > 2. router isis, passive-interface loopback X.
> >
> > Both of these methods advertise the directly connected subnet of the
> > loopback interface.
> >
> > The reason method 2 works I think, is because of the history of isis
> and
> > it's relationship with OSI CLNS.
> > With OSI networks, you address not the interface, but the router.
> > In order for ISIS to work with IP, we need to add in the IP
> information
> into
> > the ISIS LSA's. I think the passive interface command links the IP
> subnet
> > information with the ISIS process at a lower level than it would if
> the
> > protocol was ospf..
> >
> > Maybe somebody can improve on this.
> >
> > Adam
> >
> > -----Original Message-----
> > From: Kenneth Wygand [mailto:KWygand@customonline.com]
> > Sent: 23 April 2004 14:09
> > To: R&S Groupstudy; Ahmed Mustafa; ccielab@groupstudy.com
> > Subject: RE: Passive interfaces in ISIS
> >
> >
> > I don't really understand the point of making an interface "passive"
> > under IS-IS. I thought IS-IS does _not_ advertise directly connected
> > routes natively without the redistribute connected command? So if you
> > are going to make the interface "passive" so hellos and routing
> updates
> > are not sent out that interface, and enabling the interface in the
> IS-IS
> > process does not advertise the directly connected network into the
> > process, what is the difference between enabling IS-IS on a "passive"
> > interface or instead just not enabling IS-IS on that interface?
> >
> > Kenneth E. Wygand
> > Systems Engineer, Project Services
> > CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
> > Network+, A+
> > Custom Computer Specialists, Inc.
> > "The only unattainable goal is the one not attempted."
> > -Anonymous
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > R&S Groupstudy
> > Sent: Friday, April 23, 2004 4:07 AM
> > To: Ahmed Mustafa; ccielab@groupstudy.com
> > Subject: RE: Passive interfaces in ISIS
> >
> > Passive interfaces depress the transmission of routing protocol
> packets.
> > When you enables up ip router isis, and passive-interface on router1,
> > you
> > advertised r1's S1 subnet into the isis routing process. Router 2
> should
> > therefore have a route to reach S1 in router3. Router 3 however, will
> > not
> > have a router back to R2 since it does not form an adjacency with
> Router
> > 1.
> > Try adding a static on R3 for R2 S0; R2 should then be able to ping R2
> > s1
> >
> > Adam
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Ahmed Mustafa
> > Sent: 23 April 2004 08:53
> > To: ccielab@groupstudy.com
> > Subject: Passive interfaces in ISIS
> >
> >
> > Passive intereface in ISIS means actually means that advertise the
> > network
> > internally without sending any hello packets.
> >
> > I am wondering if Passive interfaces can only be assigned for stub
> > networks
> > or
> > loopback networks.
> >
> > The thing I tested was little wiered.
> >
> > I connected my routers such as:
> >
> >
> >
> > R2-----------------------------------R1----------------------------
> > --R3
> >
> >
> > R1 and R2 are connected via S0 at both ends, and R1 and R3 are
> connected
> > via
> > S1 at both ends.
> >
> > I tried this configuration:
> >
> >
> > On R1,
> >
> > I tried this:
> >
> > First I didn't enable "IP ROUTER ISIS" on R1's either S0 or S1,
> >
> > router isis
> > net 49.0010.0001.0001.0001.00
> > passive interface s0------------------------> router didn't like, and
> > gave
> > the error message something 'INVALID COMMAND IF CLNS ONLY".
> >
> >
> > I then enabled the command "IP ROUTER ISIS" on S1 only.
> >
> > I tried again to above configuration
> >
> > router isis
> > net 49.0010.0001.0001.0001.00
> > passive interface s0------------------------> command was accepted.
> >
> > I concluded that in order to advertise networks through passive
> > interfaces
> > one
> > of the router's interfaces must be enabled with 'IP ROUTER ISIS"
> >
> > But again, passive interface will not work on the link between two
> > routers.
> > It is only meant for stub networks.
> >
> > Regards,
> >
> > Ahmed
> >
> >
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