Ray Of Hope

Loopback UDP to ATM Cells and Vice Versa

A new day , a new learning. Today I was able to successfully test loop back of ATM traffic but with some difficulty.

I had this PC (Node 1) which transfers UDP packet through packeth . In the middle is the ATM card (Node 2) configured with map-from-udp and map-to-udp routes configured (to convert UDP traffic to ATM cells and vice versa). And in the end is the ADAX card (Node 3) to receive the ATM cells over AAL2 or AAL5 channels and to loop back the cells.

Looks quites simple but had some difficult time implmenting this setup.

As stated earlier, my aim was to send UDP traffic from Node 1, get it converted to Cells at Node 2 and then transfer it over AAL2 and AAL5 channel to node 3 . Node 3 will reflect back the traffic (in form of ATM Cells), Node 2 will covert the ATM cells to UDP traffic and transfer it to Node 1.

One thing I incorrectly implmented earlier was I gave the destination IP and MacAddress as the IP and Mac Address of Node 2 and i thought that when traffic will land at Node 2 (ATM AMC), it will convert that to Cells and forward it over to Node 3 (ADAX Card) . I tried a lot but it failed to forward the traffic.

So on debugging I realized that if destination IP and Mac is of Node 2, then why will it forward the UDP traffic , instead it will just consume it. (Simple routing funda.).

So I changed the destination IP on the UDP traffic to some arbitrary one, MAC as that of ethernet interface of Node 2 and things worked fine.. Good learning. .. But should not have committed such small mistake 🙁

Anshul Makkar, anshul_makkar@justkernel.com

Originally Posted On: 2010-06-01 04:01:06


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