Encapsulation failed arp incomplete

nathan.carroll · ‎04-01-2010

Hi All,

Im wondering if someone is able to help with this one. Please view the debug output below

*Mar 1 05:01:07.270: IP: tableid=0, s=119.118.126.234 (local), d=119.118.126.233 (Vlan1), routed via RIB
*Mar 1 05:01:07.270: IP: s=119.118.126.234 (local), d=119.118.126.233 (Vlan1),
*Mar 1 05:01:07.270: ICMP type=8, code=0
*Mar 1 05:01:07.270: IP: s=119.118.126.234 (local), d=119.118.126.233 (Vlan1),len 100, encapsulation failed

Protocol Address          Age (min) Hardware Addr   Type   Interf
Internet 10.199.39.1             -   9caf.ca44.4998 ARPA   Vlan2
Internet 10.199.39.3             0   0003.9d75.20a5 ARPA   Vlan2
Internet 119.118.126.233         0   Incomplete      ARPA
Internet 119.118.126.234         -   9caf.ca44.4998 ARPA   Vlan1

My setup is curentally cabled as follows

<---10.199.20.1--->fe1[Cisco 877] fe0<-----122.41.88.162---------------------122.41.88.163------> [Fiber box with Ethernet cable] > internet

Does anyone have any idea why my cisco router is unable to add a MAC address entry into the ARP table ?

Just an extra note, the interface on the cisco and the fiberbox (direct connection to the ISP) can be plugged into any other device and it works perfectally responding to pings, it just seems to be an issue with the cisco and the fiber ethernet box.

Have tried changing the cable from Straight to Crossover, no luck.

Have tested with another router and it works fine.

Please refer to my earlier post for the running config. https://supportforums.cisco.com/message/3046160#3046160

Thanks,

Nathan

Ganesh Hariharan · ‎04-01-2010

Hi All,

Im wondering if someone is able to help with this one. Please view the debug output below

*Mar 1 05:01:07.270: IP: tableid=0, s=119.118.126.234 (local), d=119.118.126.233 (Vlan1), routed via RIB
*Mar 1 05:01:07.270: IP: s=119.118.126.234 (local), d=119.118.126.233 (Vlan1),
*Mar 1 05:01:07.270: ICMP type=8, code=0
*Mar 1 05:01:07.270: IP: s=119.118.126.234 (local), d=119.118.126.233 (Vlan1),len 100, encapsulation failed

Protocol Address          Age (min) Hardware Addr   Type   Interf
Internet 10.199.39.1             -   9caf.ca44.4998 ARPA   Vlan2
Internet 10.199.39.3             0   0003.9d75.20a5 ARPA   Vlan2
Internet 119.118.126.233         0   Incomplete      ARPA
Internet 119.118.126.234         -   9caf.ca44.4998 ARPA   Vlan1

My setup is curentally cabled as follows

<---10.199.20.1--->fe1[Cisco 877] fe0<-----122.41.88.162---------------------122.41.88.163------> [Fiber box with Ethernet cable] > internet

Does anyone have any idea why my cisco router is unable to add a MAC address entry into the ARP table ?

Just an extra note, the interface on the cisco and the fiberbox (direct connection to the ISP) can be plugged into any other device and it works perfectally responding to pings, it just seems to be an issue with the cisco and the fiber ethernet box.

Have tried changing the cable from Straight to Crossover, no luck.

Have tested with another router and it works fine.

Please refer to my earlier post for the running config. https://supportforums.cisco.com/message/3046160#3046160

Thanks,

Nathan

Hi Nathan,

The "encapsulation failed" coming in the log means that the router knows on which interface it has to send the packet, but does not know how to do it.

In order to troubleshoot check out the below things

1.check show arp and check the arp entry of the fiber interface

2.If it is coming incomplete try clear arp in router and ping the fiber interface ip.

3. while pinging just enable debug arp in router,so that what is happening we can see with the logs.

Hope to Help !!

Ganesh.H

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