From: ccie2be (ccie2be@nyc.rr.com)
Date: Wed Jun 15 2005 - 13:55:05 GMT-3
I'm not sending any eigrp unicast packets ei there's no neighbor command
configured on either R1 or R3.
Also, I recall that eigrp hello packets have a TTL of 2 but I don't remember
if that applies to unicast or mcast Hello's or both.
And, interestingly enough, for the last 10 or 15 minutes, both spokes have
been showing only the hub as a neighbor. It seems that the neighbor
flapping has stopped on R3 but I have no idea why.
Very strange. I didn't change any of the config's either.
This is so weird.
TIA, Tim
-----Original Message-----
From: brussels@yandex.ru [mailto:brussels@yandex.ru]
Sent: Wednesday, June 15, 2005 12:39 PM
To: ccie2be@nyc.rr.com
Cc: brussels@yandex.ru; ccielab@groupstudy.com
Subject: RE: f/r & ei
you forgot that eigrp unicast packets are sent with TTL=1, and in this case
there is no unicast reachability between the spokes.
it seems to me that for multicast/broadcast hellos hub should also check
TTL, but a saw the same operation on different IOS versions, and may be it's
not a bug rather special feature.
to workaround this issue you can use staticly defined eigrp neighbors
on the hub and spoke topology no need for peering between spokes, due to
inconsistencity of physical and logical (L3) topology in such case.
>Thanks for responding to this post.
>
>I don't think your explanation is correct (I'm not 100% sure) but here's
>why.
>
>R1 and R3 can ping each other fine. Here's R3's config:
>
>interface Serial0/1
> ip address 183.1.123.3 255.255.255.0
> encapsulation frame-relay
> clockrate 800000
> frame-relay map ip 183.1.123.1 302 broadcast
> frame-relay map ip 183.1.123.2 302 broadcast
> no frame-relay inverse-arp
>end
>
>R3(config)#do p 183.1.123.2
>
>Type escape sequence to abort.
>Sending 5, 100-byte ICMP Echos to 183.1.123.2, timeout is 2 seconds:
>!!!!!
>Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms
>R3(config)#do p 183.1.123.1
>
>Type escape sequence to abort.
>Sending 5, 100-byte ICMP Echos to 183.1.123.1, timeout is 2 seconds:
>!!!!!
>Success rate is 100 percent (5/5), round-trip min/avg/max = 88/89/96 ms
>
>**************************
>
>Here's R1's config:
>
>interface Serial0/0
> ip address 183.1.123.1 255.255.255.0
> encapsulation frame-relay
> no fair-queue
> frame-relay map ip 183.1.123.2 102 broadcast
> frame-relay map ip 183.1.123.3 102 broadcast
> no frame-relay inverse-arp
>end
>
>R1#p 183.1.123.2
>
>Type escape sequence to abort.
>Sending 5, 100-byte ICMP Echos to 183.1.123.2, timeout is 2 seconds:
>!!!!!
>Success rate is 100 percent (5/5), round-trip min/avg/max = 56/57/60 ms
>R1#p 183.1.123.3
>
>Type escape sequence to abort.
>Sending 5, 100-byte ICMP Echos to 183.1.123.3, timeout is 2 seconds:
>!!!!!
>Success rate is 100 percent (5/5), round-trip min/avg/max = 84/89/100 ms
>
>*************
>
>So, you see both R1 and R3 can ping each other using unicast packets.
>
>Furthermore, R3 is seeing plenty of eigrp routes - all of which arrive via
>the hub, R2.
>
>R3(config)#do sir ei
> 183.1.0.0/16 is variably subnetted, 8 subnets, 2 masks
>D 183.1.58.0/24 [90/2712576] via 183.1.123.2, 00:21:49, Serial0/1
>D 183.1.17.0/24 [90/2707456] via 183.1.123.2, 00:21:49, Serial0/1
>D 183.1.2.0/24 [90/2195456] via 183.1.123.2, 00:21:49, Serial0/1
>D 183.1.78.0/24 [90/2710016] via 183.1.123.2, 00:21:49, Serial0/1
> 150.1.0.0/16 is variably subnetted, 8 subnets, 2 masks
>D 150.1.7.0/24 [90/2835456] via 183.1.123.2, 00:21:49, Serial0/1
>D 150.1.2.0/24 [90/2297856] via 183.1.123.2, 00:21:49, Serial0/1
>D 150.1.1.0/24 [90/2809856] via 183.1.123.2, 00:21:49, Serial0/1
>D 150.1.8.0/24 [90/2838016] via 183.1.123.2, 00:21:49, Serial0/1
>
>
>
>What really gets me is this: Should the spokes of a hub and spoke topology
>running eigrp become neighbors?
>
>Why yes or why no?
>
>It seems to me that there's no need for the eigrp spokes to become
neighbors
>as long as the hub has split-horizon disabled and is passing routes as it
>should.
>
>Any comments?
>
>TIA, Tim
>
>-----Original Message-----
>From: brussels@yandex.ru [mailto:brussels@yandex.ru]
>Sent: Wednesday, June 15, 2005 12:07 PM
>To: ccie2be@nyc.rr.com
>Cc: ccielab@groupstudy.com
>Subject: Re: f/r & ei
>
>hub forwards multicast hello packets between spokes. but unicast messages
is
>droped due to a lack of mapping (static or inarp).
>
>
>>Hi guys,
>>
>>This is interesting but confusing.
>>
>>R1, R2, and R3 are running eigrp over a hub and spoke f/r cloud with R2 as
>>the hub.
>>
>>
>>R1 doesn't ever see R3, the other spoke as an eigrp neighbor, but R3
>>sometimes sees R1 as a neighbor.
>>
>>On R1, the neighbor state with R3 flaps up and down.
>>
>>On R2, the hub, ip split-horizon has been disabled.
>>
>>R3#sh ip ei n
>>IP-EIGRP neighbors for process 100
>>H Address Interface Hold Uptime SRTT RTO Q
>Seq
>>Typ
>>e
>> (sec) (ms) Cnt
>Num
>>0 183.1.123.1 Se0/1 172 00:02:03 1 5000 1 0
>>1 183.1.123.2 Se0/1 136 00:40:21 36 216 0
10
>>R3#uu
>>BL-Rack3>1
>>
>>
>>Notice the uptime for R1 (1831.1.123.1) is very small relative to R2.
>>
>>Moments later.
>>
>>R3#sh ip ei n
>>IP-EIGRP neighbors for process 100
>>H Address Interface Hold Uptime SRTT RTO Q
>Seq
>>Typ
>>e
>> (sec) (ms) Cnt
>Num
>>1 183.1.123.2 Se0/1 165 00:45:33 36 216 0
10
>>
>>And, I get these messages on R3:
>>
>>R3#
>>*Mar 1 04:04:45.633: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor
>>183.1.123.1 (
>>Serial0/1) is up: new adjacency
>>
>>R3#
>>*Mar 1 04:07:50.156: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor
>>183.1.123.1 (
>>Serial0/1) is down: retry limit exceeded
>>R3#
>>*Mar 1 04:07:50.156: destroy peer: 183.1.123.1
>>
>>
>>R1(config-router)#do sh ip ei n
>>IP-EIGRP neighbors for process 100
>>H Address Interface Hold Uptime SRTT RTO Q
>Seq
>>Typ
>>e
>> (sec) (ms) Cnt
>Num
>>1 183.1.123.2 Se0/0 177 00:40:37 68 408 0
10
>>0 183.1.17.7 Et0/0 14 00:49:41 145 870 0
19
>>R1(config-router)#
>>
>>
>>Anyone know what's going on? And, know what should be done about this?
>>
>>TIA, Tim
>>
>>_______________________________________________________________________
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>
>
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>"sPAMOOBORONA" - PO^TA BEZ SPAMA W WA[EM OFISE! http://so.yandex.ru/
>
>_______________________________________________________________________
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