eap Mailing List: Re: Q: EAP retransmission & fragmentation

[Bernard Aboba (aboba]

> If both the EAP-server & EAP-authenticator share the
> responsibility of retransmission, who decides when to
> retransmit?

The EAP authenticator is responsible for retransmitting EAP packets to the
EAP peer.

Retransmission between the EAP authenticator and EAP server is handled by
AAA, *not* by EAP.  In RADIUS, the NAS owns retransmission, so the EAP
server (AAA server) does not retransmit.  In Diameter, the reliable
transport (TCP/SCTP) handles retransmission.

> I mean, EAP-authenticator can start a timer
> after forwarding the request packet and retransmit the
> packet again on the timeout.

It can do this in RADIUS.  In Diameter, the Diameter client has a state
machine for retransmission/failover.  See RFC 3539.

> So can EAP-server.

No, when the EAP server and EAP authenticator are on separate boxes, the
EAP server does not retransmit.  This is handled by AAA.