Can't ping Cisco 857 own IP address on logical ATM IF

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Dec 11th, 2008
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Hello,


Cisco 857 router is connected to Service Provider Network via ADSL line. ADSL module is integrated into Cisco.


Logical atm0.1 IF with PVC 8/35. Routed Bridged Encapsulation is Used. In Service Provider Network equipment is Non Cisco.


Everything works O'k.


But one mysterious thing ?


I can't ping from Cisco CLI own IP address located on atm0.1. Ping doesn't respond.

If I ping Default Gateway, everything is O'k. Also service provider can ping my atm 0.1 IF.


Any Idea for such behaviour? Cisco SW 12.4 (6)T8.


Best Regards,


Tomas

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Davy Ad Fri, 12/12/2008 - 01:32
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Hi Tomas,

Have you try to see if you can ping your local loop 127.0.0.1 ?

What is the output?


HTH

DAK

Giuseppe Larosa Fri, 12/12/2008 - 03:00
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Hello Tomas,

routers perform ping of their own ip addresses in different ways depending on the type of interface:

on an ethernet interface they are to ping it without sending out a packet

on an atm interface the icmp packet is sent to the other side of the link and if that device sends back the packet if you get answer


So this is not a sign of problem


I saw this during tests on ATM interface like STM-1 but I think it applies to ATM over DSL too.


Hope to help

Giuseppe


1pipantom2 Fri, 12/12/2008 - 04:53
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Hi all,


Thank You for Reply.


For the fist advice. ping to loopback 127.0.0.1 doesn't work also.


Giuseppe, You are confirmed, that I have observed also on Frame Relay and PPP links.


When pinging own interface, ping actually send packet to remote end of connection, and remote connection redirects this packet back.

In case, when two boxes are Cisco this works.


But I said in our case remote end is non-Cisco.


But somehow it is possible to change such behaviour and respond locally to ICMP reguests?


Problem is following. Lot of people configure interface and after that try to ping it.


Ping doesn't responds. So they decide, that something is wrong with IF configuration.

Best Regards,


Tomas

Giuseppe Larosa Fri, 12/12/2008 - 07:06
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Hello Tomas,

in this case you should write down a nice note that you send to all users in remote branch /sites to reduce their calls


Hope to help

Giuseppe


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