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RE: Unicasting eigrp messages using nat -do not get it posted 01/02/2006
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The statement works well with RIP but not EIGRP. For some reason, the
outside global ip adress is not translated into outside local address in
one direction(anomaly for multicast?), so EIGRP rejects unicast packet
while expecting multicast packet. RIP does not seem to care this so it
works. 

How is the way I understand the statement, this is outside source
address translation. When the packet from source 23.23.23.3 hit outside
interface, it is translated into outside local address. 

HTH..

- Dehong
-
Mar 13 04:24:02.656: NAT: s=23.23.23.2, d=224.0.0.10->23.23.23.3 [0]
Mar 13 04:24:02.656: EIGRP: Sending HELLO on FastEthernet0/0
Mar 13 04:24:02.656:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely
0/0
Mar 13 04:24:03.201: EIGRP: Received UPDATE on FastEthernet0/0 nbr
23.23.23.3
Mar 13 04:24:03.201:   AS 1, Flags 0x1, Seq 23/0 idbQ 0/0
Mar 13 04:24:03.201: EIGRP: Neighbor(23.23.23.3) not yet found
Mar 13 04:24:03.281: EIGRP: Received HELLO on FastEthernet0/0 nbr
23.23.23.3
Mar 13 04:24:03.281:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0
Mar 13 04:24:03.281: EIGRP: Ignore unicast Hello from FastEthernet0/0
23.23.23.3
Mar 13 04:24:03.522: EIGRP: Sending HELLO on Loopback0

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
nenad pudar
Sent: Sunday, January 01, 2006 9:54 PM
To: ccielab@xxxxxxxxxxxxxx
Subject: Re: Unicasting eigrp messages using nat -do not get it

Just realized that eigrp with conifg below  is nor working properly.
See few session flaps and more importantly I see no route exchanged be
teen eigrp neighbors nenad

On 1/1/06, nenad pudar <nenad.pudar@xxxxxxxxx> wrote:
>
> Hi guys
>
> I am trying to unicast the eigrp update between two neighbors using 
> nat It is working but I do not understand the principe behind this
>
> Here is the config
> interface Virtual-Template1
>  bandwidth 512
>  ip address 172.16.32.130 255.255.255.192  ip nat outside 
> **************************************
>  ip authentication mode eigrp 2 md5
>  ip authentication key-chain eigrp 2 ccie  ip summary-address eigrp 2 
> 10.17.2.0 255.255.255.0 5  ppp authentication chap PPP  ppp chap 
> hostname r1 end
>
>
>
> ip nat outside source static 172.16.32.129 224.0.0.10 
> ********************
>
>
> #R1sh ip eigrp neighbors
> IP-EIGRP neighbors for process 2
> H   Address                 Interface       Hold Uptime   SRTT   RTO
Q
> Seq Type
>                                             (sec)         (ms)
Cnt
> Num
> 0   172.16.32.129           Vi1               14 00:00:18    1  5000
1
> 0
> IP-EIGRP neighbors for process 3
>
> .855: NAT: s=172.16.32.130, d=224.0.0.10->172.16.32.129 [0] Jan  2 
> 03:23:46.199: NAT: i: eigrp (172.16.32.130 , 0) -> (224.0.0.10, 0) [0]

> Jan  2 03:23:46.199: NAT: s=172.16.32.130, d=224.0.0.10->172.16.32.129

> [0] Jan  2 03:23:50.783: NAT: i: eigrp (172.16.32.130, 0) -> 
> (224.0.0.10, 0) [0] Jan  2 03:23:50.783: NAT: s=172.16.32.130 , 
> d=224.0.0.10->172.16.32.129[0] Jan  2 03:23:55.535: NAT: i: eigrp 
> (172.16.32.130, 0) -> (224.0.0.10, 0) [0] Jan  2 03:23:55.535: NAT: 
> s=172.16.32.130, d=224.0.0.10->172.16.32.129 [0] Jan  2 03:24:00.271: 
> NAT: i: eigrp ( 172.16.32.130, 0) -> (224.0.0.10, 0) [0] Jan  2 
> 03:24:00.271: NAT: s=172.16.32.130, d=224.0.0.10->172.16.32.129 [0]
>
> #R1sh ip nat translations
> Pro Inside global         Inside local          Outside local
> Outside global
> --- 172.16.32.130         172.16.32.130         224.0.0.10
> 172.16.32.129
>
> I did this following one similar example in Cisco book but I do not 
> get it
>
>
> ip nat outside source static 172.16.32.129 224.0.0.10 statement 
> according to my understanding of how NAT works will:
>
> 1) Translate the source address 172.16.32.129 to 224.0.0.10 once the 
> packet hits outside interface
> 2) It will also translate the destination address 224.0.0.10 to
> 172.16.32.129 once the packet hits the inside interface
>
> Above you can see the nat log
>
> This statement
>
> Jan  2 03:23:46.199: NAT: s= 172.16.32.130, 
> d=224.0.0.10->172.16.32.129
>
> I can understand assuming that since the packet are locally generated 
> router "does not need explicitly defined inside interface"
>
> But I do not really get what is happening with the packet coming from 
> the other side
>
>
>  Anybody can help me about this one .
>
> thanks
> nenad

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