From: Packet Man (ccie2b@hotmail.com)
Date: Thu Feb 05 2004 - 20:10:37 GMT-3
Hey Brian,
That's a really interesting observation. thank you for pointing that out.
If you don't mind, I'd like to make sure I fully understand the implications
of what you're saying.
Without the broadcast keyword, will a ping to the dot254 address be
successful?
Also, what do you mean when you say, "InARP for ATM does not automatically
map the broadcast keyword like Frame Relay InARP does."?
Would that cause the neighbor to flap up and down? Why?
Does this have something to do with the fact that Eigrp multicasts hello
packets?
Thanks very, very much.
>From: "Brian Dennis" <bdennis@internetworkexpert.com>
>To: "'Packet Man'" <ccie2b@hotmail.com>,<ccielab@groupstudy.com>
>Subject: RE: Eigrp
>Date: Thu, 5 Feb 2004 12:55:59 -0800
>
>Packet Man,
> A common problem that you can run into with EIGRP over ATM when
>using InARP is that InARP for ATM does not automatically map the broadcast
>keyword like Frame Relay InARP does. This can cause your EIGRP
>relationship
>to not come up. See below:
>
><Config>
>interface ATM0/0/0
> ip address 54.3.2.6 255.255.255.0
>!
> pvc 3/100
> !
>!
>router eigrp 10
> network 54.0.0.0
></Config>
>
>Rack3R6#sho atm map
>Map list ATM0/0/0_ATM_INARP : DYNAMIC
>ip 54.3.2.254 maps to VC 7, VPI 3, VCI 100, ATM0/0/0
>
>*** Notice the broadcast keyword is missing ***
>
>Rack3R6#sho ip ei n
>IP-EIGRP neighbors for process 10
>H Address Interface Hold Uptime SRTT RTO Q
>Seq
>Type
> (sec) (ms) Cnt
>Num
>0 54.3.2.254 AT0/0/0 11 00:00:49 1 5000 1 0
>
>
>*** RTO 5000. This isn't good ;-) ***
>
>Rack3R6#sho ip route ei
>
>*** No EIGRP routes in the table. This isn't good either ;-) ***
>
>*** Now add the broadcast keyword under the PVC to solve the issue ***
>Rack3R6#conf t
>Enter configuration commands, one per line. End with CNTL/Z.
>Rack3R6(config)#int atm0/0/0
>Rack3R6(config-if)#pvc 3/100
>Rack3R6(config-if-atm-vc)#broadcast
>Rack3R6(config-if-atm-vc)#exit
>Rack3R6(config-if)#do sho atm map
>Map list ATM0/0/0_ATM_INARP : DYNAMIC
>ip 54.3.2.254 maps to VC 7, VPI 3, VCI 100, ATM0/0/0
> , broadcast
>
>Rack3R6(config-if)#do sho ip ei n
>IP-EIGRP neighbors for process 10
>H Address Interface Hold Uptime SRTT RTO Q
>Seq
>Type
> (sec) (ms) Cnt
>Num
>0 54.3.2.254 AT0/0/0 14 00:00:02 1 2000 1 0
>
>
>Rack3R6(config-if)#do sho ip route ei
>D 200.0.0.0/24 [90/146432] via 54.3.2.254, 00:00:03, ATM0/0/0
>D 200.0.1.0/24 [90/146432] via 54.3.2.254, 00:00:03, ATM0/0/0
>D 200.0.2.0/24 [90/146432] via 54.3.2.254, 00:00:03, ATM0/0/0
>D 200.0.3.0/24 [90/146432] via 54.3.2.254, 00:00:03, ATM0/0/0
>
>*** Problem solved ***
>
>Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
>bdennis@internetworkexpert.com
>Internetwork Expert, Inc.
>http://www.InternetworkExpert.com
>Toll Free: 877-224-8987
>Direct: 775-745-6404 (Outside the US and Canada)
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Packet Man
>Sent: Thursday, February 05, 2004 12:27 PM
>To: turgon2004@hotmail.com; ccielab@groupstudy.com
>Subject: RE: Eigrp
>
>Hey Gary,
>
>Yes, I did. And, I was trying to use that info. I liked how it should
>possible to get an idea of the hello interval from the show ip ei nei
>command. I also very much liked Scott's idea of using the timestamps to
>see
>
>how often the Hello's come and go - although in practice it seems very
>difficult to sort through all the output to find just the hello's from a
>particular neighbor. Another problem is that the timestamps on the local
>router don't match up exactly with the interval set on the remote router.
>For example, I noticed that when the hello was set to 25 seconds on the
>remote rtr, the timestamps on the local router indicated that the hello
>interval was 23 seconds. I don't know why that is but that's what I saw.
>
>While playing around, however, I noticed that Eigrp doesn't (it seems)
>automatically change the holdtime interval to be 3 times the hello
>interval.
>
> I also noticed that even though Eigrp isn't suppose to require that
>these
>intervals match at both ends of the link, if they don't, the neighbor flaps
>up and down.
>
>I'm going to try using different combo's of intervals on one end of the
>link
>
>to see what causes the neighbor to flap, but so far, it seems that if faced
>with this type of scenario in the actual lab the best thinkg to do is the
>following:
>
>a) use time stamps to see how often Hello's are being rec'd
>b) then change both the hello and holdtime intervals on the router you
>control.
>
>
>
> >From: "Gary Duncanson" <turgon2004@hotmail.com>
> >To: ccie2b@hotmail.com
> >Subject: RE: Eigrp
> >Date: Thu, 05 Feb 2004 19:25:24 +0000
> >
> >did you get my email with the links yet? Might help. It hasn't appeared
>on
> >the list yet.
> >
> >
> >>From: "Packet Man" <ccie2b@hotmail.com>
> >>Reply-To: "Packet Man" <ccie2b@hotmail.com>
> >>To: cchurch@wamnetgov.com, turgon2004@hotmail.com
> >>CC: ccielab@groupstudy.com
> >>Subject: RE: Eigrp
> >>Date: Thu, 05 Feb 2004 14:21:42 -0500
> >>
> >>Hi Chuck,
> >>
> >>Thanks for getting back to me on this.
> >>
> >>Actually, this is a practice lab problem. The issue here is to figure
>out
>
> >>how the remote router was (mis) configured by finding and using the
> >>appropriate debugs - and then configuring the local router as to match.
> >>So, it's "known" that there's no cable, interface, hardware issue here,
> >>although in the real world those sort of things would be among the first
> >>to check.
> >>
> >>The idea is to be able to overcome this type of potential "nasty" in the
> >>actual lab where you don't access to the backbone router - only your
> >>router which is connected to the backbone router. I'm doing this with
> >>every routing protocol as an exercise to get stronger with using and
> >>interpreting debugs.
> >>
> >>With other protocols, it seems easier to find mis-matched parameters,
>but
> >>I'm having a heck of time doing so with Eigrp. The output from their
> >>debugs is unintellible for the most part and appears to be very poorly
> >>documented.
> >>
> >>
> >>
> >>
> >>>From: "Church, Chuck" <cchurch@wamnetgov.com>
> >>>To: "Packet Man" <ccie2b@hotmail.com>,<turgon2004@hotmail.com>
> >>>CC: <ccielab@groupstudy.com>
> >>>Subject: RE: Eigrp
> >>>Date: Thu, 5 Feb 2004 12:47:18 -0600
> >>>
> >>>Is this a new installation, or has it been in place for a while? If
>it's
>
> >>>flapping and been in place for a while, I'd say it's more likely packet
> >>>loss due to something, rather than mis-configuration. A failing
>circuit
> >>>will usually cause hellos to be lost and up/down neighbor messages to
>be
> >>>logged. Check your DSUs for errors, assuming it's serial ints. And
> >>>check the serial ints for errors, queue drops, etc. A pegged CPU on
>the
> >>>router can also cause neighbors to drop.
> >>>
> >>>Chuck Church
> >>>CCIE #8776, MCNE, MCSE
> >>>Wam!Net Government Services
> >>>13665 Dulles Technology Dr. Ste 250
> >>>Herndon, VA 20171
> >>>Office: 703-480-2569
> >>>Cell: 703-819-3495
> >>>cchurch@wamnetgov.com
> >>>PGP key:
> >>>http://pgp.mit.edu:11371/pks/lookup?op=index&search=cchurch%40wamnetgov.c
>om
> >>>
> >>> > -----Original Message-----
> >>> > From: Packet Man [mailto:ccie2b@hotmail.com]
> >>> > Sent: Thursday, February 05, 2004 1:40 PM
> >>> > To: turgon2004@hotmail.com
> >>> > Cc: ccielab@groupstudy.com
> >>> > Subject: RE: Eigrp
> >>> >
> >>> >
> >>> > Thanks for getting back to me.
> >>> >
> >>> > As it happens, I tried both of those debugs but the output
> >>> > was, for the most
> >>> > part, undecipherable and I couldn't tell from that output if
> >>> > there was a
> >>> > mis-match.
> >>> >
> >>> > Do you know what specifically I should look for in the output
> >>> > from those
> >>> > debugs to see if there's a Hello or Hold interval mismatch?
> >>> >
> >>> > Thanks iv advanced
> >>> >
> >>> >
> >>> > >From: "Gary Duncanson" <turgon2004@hotmail.com>
> >>> > >To: ccie2b@hotmail.com
> >>> > >CC: ccielab@groupstudy.com
> >>> > >Subject: RE: Eigrp
> >>> > >Date: Thu, 05 Feb 2004 18:34:49 +0000
> >>> > >
> >>> > >debug eigrp neighbor
> >>> > >debug eigrp packet
> >>> > >
> >>> > >
> >>> > >>From: "Packet Man" <ccie2b@hotmail.com>
> >>> > >>Reply-To: "Packet Man" <ccie2b@hotmail.com>
> >>> > >>To: ccielab@groupstudy.com
> >>> > >>Subject: Eigrp
> >>> > >>Date: Thu, 05 Feb 2004 12:50:24 -0500
> >>> > >>
> >>> > >>Hi all,
> >>> > >>
> >>> > >>I'm trying to debug a flapping Eigrp neighbor. I can
> >>> > access my local
> >>> > >>router's config but I can't access the remote router.
> >>> > >>
> >>> > >>I'm trying to figure out which debug to use to see if
> >>> > there's a mismatched
> >>> > >>hello or holdtime interval, but can't seem to find the
> >>> > right debug to use.
> >>> > >>
> >>> > >>Anybody have any ideas?
> >>> > >>
> >>> > >>Thanks in advanced.
> >>> > >>
> >>> > >>_________________________________________________________________
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