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Archive of PING on HDLC on Serial Interfaces

Geez... I have to defend a comment I made regarding pinging an HDLC Serial Interface connection with a .252 mask. I made the comment that when you ping the local serial interface, the packets actually traverse the wan link end-to-end before returning the resulting data. A co-worker claims I am crazy. Have I gotten too old and should be put out to pasture? Can someone provide substantiating documentation to my claim? Thx.

AGE

2 REPLIES

Re: Archive of PING on HDLC on Serial Interfaces

Hi Age

U hve given right comments regarding the ping command .To successfully ping your own interface address, another router must send back the ICMP echoes and the echo replies.

when you ping from the router to its own interface on an HDLC serial interface, the packet goes to the connected router and comes back. for eg: say u have 2 routers A and B, connected via back to back serial link. If you ping serial interface on A from router A, the packet goes to the connected interface (serial int on B) and then comes back.

In case of multipoint interfaces u can have multiple destinations, the router must have mapping for every destination. if mapping is not made for our interface address to point toward other routers, which would send our ICMP packets back, the router does not have any layer-two to layer-three mapping for its own address and does not know how to encapsulate the packet. An encapsulation failure results.

You cannot ping from one spoke to another spoke in a hub and spoke configuration using multipoint interfaces because there is no mapping for the other spokes' IP addresses. Only the hub's address is learned via Inverse Address Resolution Protocol (IARP). If you configure a static map using the frame-relay map command for your IP address or the IP address of a remote spoke to use the local data link connection identifier (DLCI), you can ping your interface address and the addresses of other spokes

Regds

Prem

Silver

Re: Archive of PING on HDLC on Serial Interfaces

you can prove this to your co worker by pinging your own interface then pinging the other side of thie line. When you ping your own interface the ping response time is doubled.

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