From: Scott Morris (swm@emanon.com)
Date: Mon Oct 17 2005 - 09:36:16 GMT-3
There is no equivalent to the update-source in EIGRP. You must make your
subnets match (change the primary address in a secondary environment).
Don't ya hate when your RAM fills up? I've tried compression routines, but
I still lose stuff.
:)
Scott
-----Original Message-----
From: Tim [mailto:ccie2be@nyc.rr.com]
Sent: Monday, October 17, 2005 7:45 AM
To: swm@emanon.com; 'Jongsoo'
Cc: 'Chris'; ccielab@groupstudy.com
Subject: RE: TTL on RIP updates
Hey Guys,
I'm fairly sure I did or discussed a practice lab where there was a hub and
spoke topology over f/r and no sub-interfaces were allowed and disabling
split-horizon also wasn't allowed. And, of course, the spokes had to pass
routing updates to each other.
The solution was to use unicast updates (I vaguely recall) which worked only
because the TTL was 2 in Cisco implementation. The TTL equally 2 was what
really stuck in my mind because I had never heard of such a thing up until
that point and was astounded by this revelation.
Here's what I'm still not sure about. Was eigrp or rip or either the
routing protocol where this TTL = 2 applied?
Since nature only blessed me with 32 mb of ram, I have trouble remembering
all the details. But later today I'll have a chance to test this out and
report back.
As for the no validate-source-update command, yes, Scott, that will be
needed for RIP but I don't recall if there's an equivalent command for
eigrp. Any thought on that?
Tim
-----Original Message-----
From: Scott Morris [mailto:swm@emanon.com]
Sent: Sunday, October 16, 2005 11:04 PM
To: 'Jongsoo'
Cc: 'Chris'; 'Tim'; ccielab@groupstudy.com
Subject: RE: TTL on RIP updates
Broadcasts to 255.255.255.255 inherently have TTL1, as they are local link
as well...
As for the unicasts, I've never paid attention in a sniffer for it, but I
would assume that it would follow the same length. Spec says that neighbors
are supposed to share a common subnet, but I've never tried making a RIP
neighbor further away without tunnels involved!
Give it a whirl, see what happens! Don't forget to use "no
validate-update-source" though to avoid confusions.
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jongsoo
Sent: Sunday, October 16, 2005 10:49 PM
To: Scott Morris
Cc: Chris; Tim; ccielab@groupstudy.com
Subject: Re: TTL on RIP updates
That proves the multicast should be 1.
What about the broadcast/unicast rip packets?
I think they all should be 1 as well
Are there any supporting standards? or IOS just does that?
On 10/16/05, Scott Morris <swm@emanon.com> wrote:
>
> All packets using 224.0.0.x (link local multicast) are, as defined,
> link local. Meaning the TTL is 1.
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of Chris
> Sent: Sunday, October 16, 2005 10:13 PM
> To: 'Tim'; ccielab@groupstudy.com
> Subject: RE: TTL on RIP updates
>
> Looking through the RFC, there does not seem to be anything that
> specifies that an IP packet containing a RIP update should mark IP
> header TTL any differently then whatever the default IP stack
> implementation dictates for a TTL. I would not think there would be
> any reason to do so since RIP normally sends updates to neighbors by
> broadcast or multicast which would bound the packet to the closest
> router where TTL would normally decrement, but that is just me
> theorizing. As I said the rfc does not say anything about marking the
> IP header TTL for RIP any differently.
>
>
>
>
> Chris
>
>
>
> --------------------------------------------------
>
> Christopher Larson CCIE#12380, PMP
> Superior Technology Networks Corp
> www.supertechnetworks.com <http://www.supertechnetworks.com> -
> Technology Consulting www.ccierackrental.com
> <http://www.ccierackrental.com> -Cisco Rack Rental
> tel: 703 577 3303 fax: 703 286 5018
>
> --------------------------------------------------
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of Tim
> Sent: Sunday, October 16, 2005 4:24 PM
> To: ccielab@groupstudy.com
> Subject: TTL on RIP updates
>
> Hi guys,
>
>
>
> I seem to recall that the TTL for rip updates is 2.
>
>
>
> Is that true only if the neighbor command is used? Or if the default
> dest address is 224.0.0.9 <http://224.0.0.9>? Or, never?
>
>
>
> TIA, Tim
>
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