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%IP-3-LOOPPAK: Looping packet detected and dropped

Unanswered Question
Aug 12th, 2012
User Badges:

Dear All,


IOS : c3900e-universalk9-mz.SPA.151-1.T.bin

Router: Cisco 3945


We are getting error msgs :


Aug 13 06:26:57: %TRACKING-5-STATE: 50 ip sla 50 reachability Up->Down
Aug 13 06:26:58: %TRACKING-5-STATE: 55 list boolean and Up->Down
Aug 13 06:26:58: %IP-3-LOOPPAK: Looping packet detected and dropped -
Aug 13 06:27:12: %TRACKING-5-STATE: 50 ip sla 50 reachability Down->Up
Aug 13 06:27:13: %TRACKING-5-STATE: 55 list boolean and Down->Up


Aug 13 06:32:57: %TRACKING-5-STATE: 50 ip sla 50 reachability Up->Down
Aug 13 06:32:58: %TRACKING-5-STATE: 55 list boolean and Up->Down
Aug 13 06:32:58: %IP-3-LOOPPAK: Looping packet detected and dropped -
Aug 13 06:33:12: %TRACKING-5-STATE: 50 ip sla 50 reachability Down->Up
Aug 13 06:33:13: %TRACKING-5-STATE: 55 list boolean and Down->Up

Error coming after Configuration of :

track 50 ip sla 50 reachability

!

track 51 ip sla 51 reachability

!

track 55 list boolean and

object 50

object 51

!

interface GigabitEthernet0/0

description ***Local LAN***

ip address 172.24.32.250 255.255.255.0

no ip redirects

no ip unreachables

no ip proxy-arp

ip nbar protocol-discovery

ip flow ingress

ip policy route-map RM-EXCHG-AIRTEL

load-interval 30

duplex auto

speed auto

!



route-map RM-EXCHG-AIRTEL permit 15

match ip address EXCHG-2K10

set ip next-hop verify-availability 172.24.32.249 1 track 55

set ip next-hop 172.24.32.250

track 50 ip sla 50 reachability
!
track 51 ip sla 51 reachability
!
track 55 list boolean and
object 50
object 51
!

ip sla 50

icmp-echo 172.35.113.241

frequency 20

ip sla schedule 50 life forever start-time now


ip sla 51 

icmp-echo 100.100.100.90 

frequency 20

ip sla schedule 51 life forever start-time now


route-map RM-EXCHG-AIRTEL permit 15
match ip address EXCHG-2K10
set ip next-hop verify-availability 172.24.32.249 1 track 55
set ip next-hop 172.24.32.250 (Local Interface - LAN of this router)


Can anybody help to find out why this error is comming and how to resolve the same?


Regards



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Tomas Fidler Sun, 08/12/2012 - 23:49
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Are you sure that you want to set next hop to IP address of routers own IP? ... What is exact purpose of it?


Normaly, if you try to configure static route this way: ip route x.x.x.x y.y.y.y 172.24.32.250 (ip address on this router), it warn you, that this is a mistake. You cannot say "next hop is our own IP"... what can router do with those packets? It should loop those packets over and over, till TTL is decremented to zero?


So what you want to configure using set ip next-hop 172.24.32.250?

Dipesh Patel Mon, 08/13/2012 - 00:12
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Dear Tomas,


The purpose of this Route-map is :


Till the Tracked IPs are reachable my next hop will be 172.24.32.249 (Other Router) and if any of the tracked Ips are unreachable than my next-hop should be 172.24.32.250 (Local Router Only).


So it's required to remove the set ip next-hop 172.24.32.250

Will it take next hope = Local by default?


Regards

Tomas Fidler Mon, 08/13/2012 - 00:29
User Badges:

I'm still not sure about, what you want to do.

If you dont specify next hop inside routemap, it will be routed according actual routing table (I hope )

If you want to "deliver packet to local router" in a matter "my router should be destination" ... You can use NAT.

If you want just to drop that packet if next hop is unreachable... route it to NULL interface:

     http://www.cisco.com/en/US/docs/ios/12_0/interface/configuration/guide/iclogint.html#wp333


Hope one of this is an answer for you

Dipesh Patel Mon, 08/13/2012 - 00:55
User Badges:

Dear Tomas,


My purpose is to send specific traffic via One link say Airtel and rest of traffic via One Link say TATA.


Traffic  Flow:


For All Traffic :


CORE switch -----  TATA CE router  ----- to Dest.



For Specific Traffic :


CORE switch -----  TATA CE router ----- AIRTEL CE router (If Airtel WAN IP Addresses are Reachable) ----- to Dest.


And when Airtel WAn IPs are unreachable than my traffic should flow via Actual Routing.


Hope you understand now.


How can i resolve this error.


Regards

Tomas Fidler Mon, 08/13/2012 - 01:34
User Badges:

ok...  just erase the line "set ip next-hop 172.24.32.250" and it will work.


if you not specify next hop (or other policy routing that dicatates to omit routing table) inside route-map entry, traffic is routed thru Actual Routing.

If you specify conditional next-hop and condition is not OK, packet will be forwarded tru Actual Routing too (it is almost the same as not specifiing next-hop) ... this is behavior you want to acomplish.

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