Does self ping works on Dialer interface

[pakothan]

Hi,

I have the below configurations done on a 2900 router

interface FastEthernet0/1/1
no ip address
ip virtual-reassembly in
ip virtual-reassembly out
duplex auto
speed auto
end

interface FastEthernet0/1/1.2
encapsulation dot1Q 102
ip virtual-reassembly in
ip virtual-reassembly out
pppoe enable group global
pppoe-client dial-pool-number 1 dial-on-demand
no cdp enable
end

interface Dialer1

mtu 1492

bandwidth 512

ip address 20.1.2.133 255.255.255.0

ip virtual-reassembly in

ip virtual-reassembly out

encapsulation ppp

dialer pool 1

dialer idle-timeout 60

dialer-group 1

no cdp enable

end

I would like to know, if the IP address assigned to dialer1 interface "20.1.2.133" would be listed in "show arp" ?, as it failed to list on our router and I want to know if this is an expected behavior ?

Secondly, does self ping 20.1.2.133 (dialer interface IP) work ?

2900a#ping 20.1.2.133

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 20.1.2.133, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

Thanks,

[Peter Paluch]

Hi,

Because the 20.1.2.133 is on a Dialer interface which uses PPP encapsulation, this IP address will not be placed into your ARP table. The ARP table maps IP addresses to their MAC addresses, however, on a Dialer, the IP is encapsulated into PPP frames, not into Ethernet frames. Therefore, there is no MAC address for the 20.1.2.133 to map it to.

In addition, the ping on the 20.1.2.133 should work only if the PPP session is up and running. On a PPP link, pinging your own IP address results in the ICMP ECHO message being sent out to the other party even though the destination is your own IP address. The other party must return the packet back to you - which also means it must be aware how to route the packet back. All of this can be accomplished only if the PPP session is already up and working.

Best regards,

Peter

[pakothan]

Hi Peter,

Thanks for sharing the info.

-Pavana

[kdsingh007]

Thanks Peter