From: Packet Man (ccie2b@hotmail.com)
Date: Thu Feb 05 2004 - 20:28:51 GMT-3
Thanks for that - I had no idea (or if I did I certainly forgot a long time
ago).
But, would forgetting the broadcast keyword make the Eigrp neighbor flap up
and down ...
or would the neighbor nver come up in the first place?
I want to make sure I diagnose a flapping Eigrp neighbor correctly since I
was able to create a flapping neighbor problem in my lab by changing the
Hello interval on one side of a link. It sounds like this might also cause
a flapping neigbor symptom.
Thanks again. It's great to better understanding this.
>From: "Brian Dennis" <bdennis@internetworkexpert.com>
>To: "'Packet Man'" <ccie2b@hotmail.com>,<ccielab@groupstudy.com>
>Subject: RE: Eigrp
>Date: Thu, 5 Feb 2004 15:16:03 -0800
>
>Packet Man,
> Yes, the broadcast keyword is not needed to ping across.
>
> When Frame Relay InARP creates a layer 3 to layer 2 mapping it
>automatically includes the broadcast keyword for the mapping. With ATM
>InARP it does not. This means that you'll need to include the broadcast
>keyword under the PVC. The broadcast allows multicast and broadcast
>packets
>to be sent across the PVC.
>
>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: Packet Man [mailto:ccie2b@hotmail.com]
>Sent: Thursday, February 05, 2004 2:55 PM
>To: bdennis@internetworkexpert.com; ccielab@groupstudy.com
>Subject: RE: Eigrp
>
>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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