From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Jun 22 2004 - 17:03:06 GMT-3
RE: Routing without routing protocolHi Wayne,
Wow, you really thought alot about this. Very impressive.
I really liked the irdp method since I was aware of it but not sure how to
really implement it - what gets enabled on what device.
But, unfortunately, each method you discussed violated either the specific
constraints of the task or the general lab rules such as don't use static,
default, or PBR. Don't add or change ip address. Don't add routing protocols
unless specifically stated.
But, of all the ways you mentioned, why didn't you mention NAT? Wouldn't that
meet the requirements in your opinion?
Thanks
----- Original Message -----
From: Baety Wayne A 30 SIG BN RS3 (cn)
To: 'ccie2be' ; MMoniz ; Group Study
Sent: Tuesday, June 22, 2004 3:47 PM
Subject: RE: Routing without routing protocol
The simplest solution is to enable OSPF on the 3550 and add the lo0 and
3550-R5 links to your OSPF routing process. But if you cannot enable OSPF (by
the lab specifically stating you may not enable OSPF on the 3550-R5 link), the
next simplest solution is to enable another shared routing protocol on the
3550-R5 link and then selectively redistributing learned networks into the
OSPF process on R5. Many alternate routing protocols have a way of
self-originating a default route on R5 to your 3550, including OSPF, and then
filtering all other routes. A routing protocol generated default route
doesn't violate the no "static default" rule. You may do the second solution
as long as the lab doesn't have verbiage about not enabling any
routing-process on the 3550-R5 link.
The third option is to rely on proxy arp on the 3550, which in most cases
leads to arp cache thrashing, is a performance hit and shouldn't be used in a
live network. By enabling proxy arp on R5 (on by default) and using a shorter
subnet mask on the 3550, the 3550 will use arp to obtain reach-ability to the
rest of the network. You can also use secondary networks on the 3550 to make
it believe other networks are local to its R5-3550 link, in which case R5 will
respond with an arp reply for each instance. Then use PBR on R5 to reach the
loopback of the 3550.
The fourth option is to disable routing on the 3550 and use ip
default-network pointing to R5. This takes care of one direction, 3550 to the
rest of the world. Then use PBR on R5, creating a route-map pointing to
destinations of lo0 to the 3550. This takes care of reach-ability to the
3550's lo0, both traffic directions satisfied. If the lab specifically states
you can not use a _default network_ (note: this is not a static default route
which is of the form ip route 0.0.0.0 x.x.x.x....) or specifically states you
can not disable routing on the 3550, then there are other ways of getting the
3550 to view R5 in "default" ways. IRDP is one, which requires you to disable
routing on the 3550 and enabling IRDP style Gateway Discovery Protocol. DHCP
is another (requires the EasyIP feature set). IRDP relies on the fact that
you configure R5 (by enabling ip irdp) to broadcast or multicast hello
messages on the 3550-R5 link. What's neat about IRDP is that you can
configure static routes with it w/o violating many labs static route rule w/
its proxy-advertise feature. If you enable ip gdp irdp on the 3550 and ip
irdp on R5 you can take care of both traffic directions.
Keep in mind these labs are designed to test how fluid you are with
configuring a Cisco router. So, learn all the ways you can configure
reach-ability and you should be all set. (Ever heard of ODR?)
Regards,
WAYNE A. BAETY, Contr, 30SIG BN
MCSE+I, MCSD, MCDBA, CCNP+Voice
Resident System Support Specialist
Office: (808) 655-6761
Cell: (808) 779-3776
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Tuesday, June 22, 2004 5:17 AM
To: MMoniz; Group Study
Subject: Re: Routing without routing protocol
Hey Mike,
Option isn't allowed - the instructions explicitly told me to enable ip
routing on the 3550.
Re: irdp. I thought of that this morning but I thought if irdp were used, it
would have to be on the 3550. However, since there's no routing protocol
running on the link between the 3550 and R5, there wouldn't be any routing
updates to listen for.
Also, if I remember correctly, irdp only listens for rip or igrp updates and
only ospf is running on R5.
I think there's still something else I'm missing.
Thanks, I'm sure I'll find out, Tim
----- Original Message -----
From: "MMoniz" <ccie2002@tampabay.rr.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study" <ccielab@groupstudy.com>
Sent: Tuesday, June 22, 2004 10:28 AM
Subject: RE: Routing without routing protocol
> Well I would say you have basically 2 options here.
>
> 1. Use IRDP on R5
>
> 2. Disable IP routing on the Cat and configure a default-gateway. This is
> not a static route or a static network!!
>
> Mike
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> ccie2be
> Sent: Tuesday, June 22, 2004 10:10 AM
> To: Group Study
> Subject: Routing without routing protocol
>
>
> Hi All,
>
> This one got me.
>
> 3550 has routing enabled but no routing protocols enabled.
>
> It's only path to the rest of the network is via R5. All other routers on
> the
> other side of R5 must be able to ping the 3550's loopback.
>
> I'm allowed to use one static route on R5.
>
> This is what it looks like:
>
> 3550 lo0 fa0/5 ------- e0/1 R5 ----- rest of network
>
> How do I provide reachabiltiy to the 3550's lo0 without violating lab
rules
> ie
> no default routes or default networks and
> no static routes except the one explicitly allowed here?
>
> Please tell me what I'm missing. Thanks, Tim
>
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