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victor.shalaginov avatar image
victor.shalaginov asked sreerag.parameswaran answered

Why PPPoE Server "AC Name" field not works in Avalanche?

My question about Avalanche PPPoE Server. I configure Enable PPP and Enable PPPoE options in Server->Subnets configuration and AC Name and Service Name. I tried to set up a PPPoE session with third party PPPoE client (not Avalanche port). I checked Wireshark pcap and found that there is no AC-Name tag in PADO from PPPoE Server on Avalanche port. PPPoE AC-Name Tag in PADO must be according to RFC 2516. (The PADO packet MUST contain one AC-Name TAG containing the Access Concentrator's name.) What else should I configure to enable AC-Name tag in PADO from Avalanche PPPoE Server?
Avalanchepppoeac-namepppoe serverservice name
pppoe server pado.png (187.2 KiB)
spirent config.png (31.4 KiB)
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sreerag.parameswaran avatar image
sreerag.parameswaran answered
Hello Victor, please raise a service request with - **support@spirent.com** and report this issue. Thanks, Sreerag
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victor.shalaginov avatar image
victor.shalaginov answered victor.shalaginov edited
Hello Sreerag, thank you for your help. I tried different PPPoE clients (incl. Windows 7 PPPoE client) but I can't configure AC-Name tag in PADI. The same PPPoE clients can set up a PPPoE session with Spirent Test Center L2-L3 application. I'll open a service request, because Avalanche not works according to PPPoE RFC 2516. I also found that Avalanche sends PADO, even if there is no Service-Name tag in PADI. ![alt text][1] [1]: /storage/temp/4506-pppoe+padi+pado_1.png

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sreerag.parameswaran answered
Hello Victor, Yes you are correct, PADO is missing the AC-Name tag. That's why I had mentioned that when client PADI has a prefered AC Name tag, Avalanche Server responds with the configured/available AC Name. Session proceeds only for matching AC names, else retries occur before the sessions time out. PADI from your PPPoE client is not having any AC-name tags, hence no answer from server. Could you please try configuring AC-Name at client level so that the PADI contains that? Thanks, Sreerag
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victor.shalaginov answered victor.shalaginov edited
Dear Sreerag, thanks. The problem is in PADO answer from Avalanche as PPPoE Server. PADO message is without AC-Name tag. RFC 2516 5.2 says: **The PADO packet MUST contain one AC-Name TAG containing the Access Concentrator's name, a Service-Name TAG identical to the one in the PADI** So Service-Name tag is ok, but where is AC-Name tag? it MUST be in PADO. RFC 2516 5.3 says: **The Host looks through the PADO packets it receives and chooses one. The choice can be based on the AC-Name or the Services offered.** So a PPPoE client can't choose an Access Concentrator = Avalanche and set up a PPPoE session, because there is no AC-Name tag in PADO. There is no PADR message from PPPoE client. ![alt text][1] Correct me if I am wrong. [1]: /storage/temp/4501-pppoe+service-name+but+no+ac-name.png

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sreerag.parameswaran answered
Hello Victor, The Techpub link that you attached says (About a Server) "To determine whether it can service a particular client request, the router matches the service name tag received in the PADI packet against the service name tags configured in its service name table. If a matching service name tag is found in the PPPoE service name table, the router sends the client a PADO packet that includes the name of the AC from which it was sent. ***If no matching service name tag is found in the PPPoE service name table, the router drops the PADI request and does not send a PADO response to the client.***" This seems to be the same behavior of Avalanche as well, correct me if I am wrong. Thanks, Sreerag
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victor.shalaginov avatar image
victor.shalaginov answered victor.shalaginov edited
Sreerag, thank you for the respond. I configued AC-Name and Service-Name tags for the client. PPPoE client sends PADI with Service-Name tag. When PADI has a Service-Name tag Avalanche PPPoE Server responds with PADO only when Service-Name fields match. But according to RFC 2516 and different tech docs PADO must contain AC-Name tag. The same PPPoE client can set up PPPoE session with Spirent Test Center. I still can't set up a PPPoE Session with Avalanche. http://www.juniper.net/techpubs/en_US/junos13.3/topics/concept/pppoe-service-name-tables-understanding.html

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sreerag.parameswaran answered
Do you have any preferred AC name for the clients? Could you try configuring AC Name at Client level too? I observed that when PADI has a prefered AC Name tag, Server responds with the configured/available AC Name. Session proceeds only for matching AC names, else retries occur before the sessions time out. Thanks, Sreerag
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