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UDP Issues

UDP Issues. PWE3 – 61 th IETF 11 - 11 - 2004. Yaakov (J) Stein. Service Provider Model. in the standard PWE3 model emulation is PE to PE IWF located at PE AC is native service. PW. native service. native service. CE. CE. IWF. PE. PE. IWF. attachment circuit. attachment

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UDP Issues

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  1. UDP Issues PWE3 – 61th IETF 11 - 11 - 2004 Yaakov (J) Stein

  2. Service Provider Model in the standard PWE3 model • emulation is PEto PE • IWF located at PE • AC is native service PW native service native service CE CE IWF PE PE IWF attachment circuit attachment circuit PSN

  3. Enterprise Model there is an alternative model (CE2E) • emulation is CEto CE (see draft-stein-pwce2e-00) • IWF located at CE • what runs over the AC ? PW CE IWF IWF CE PE PE attachment circuit attachment circuit PSN

  4. AC possibilities MPLS AC • extend MPLS towards the customer • set up PWs from CEs to PEs • splice (stitch/switch) the access PWs and core PW UDP/IP AC • leave MPLS in the core network • use UDP/IP from CEs to Pes • terminate UDP/IP at the PE and send over MPLS PW other AC possibilities • L2TP • MPLS over IP • native service over IP using GRE (when defined) • MPLS over IP using GRE

  5. List discussion • there was a lively discussion of this issue on the list • over 50 emails from 16 participants • the following 3 slides summarize what was said

  6. UDP PW advantages • UDP/IP is familiar to enterprise customer base (Stewart) • PW label as UDP Port number reduces overhead (Yaakov) • already extensively deployed for TDM PWs (Yaakov,Stewart) • reuse of AVT protocols (Sasha, Ron, Amnon, Andy) • simplify NAT traversal (Yaakov, Mark)

  7. UDP PW disadvantages • hard to provide QoS assurances w/o co p2p trail (Neil) • there should be no layer networks above UDP • no operator has spoken out • large number of UDP ports - doesn’t scale (Mark) • less than 64K port numbers altogether • increases state maintained in NAT/Firewall • need protocol for UDP port signaling (Yaakov) • UDP checksum introduces processing overhead (Mark) • why introduce new PW type at such a late stage when we already have MPLS and L2TP? (Eric, Richard) • potential security problems (Stewart) • potential congestion control problems (Stewart)

  8. Misc comments • need to reply to ITU liaison (Stewart) • PWE charter aimed at operators/SPs not customers (Ben, Mark) • wrong, but hard to stop customers from using it (Neil) • no consensus here (Eric) • discussion should be diverted to AVT (Ron, Andy) • but CE-CE PWs not in AVT charter (Sasha) • UDP OK for VoIP since adapts an application but for adapting a layer network (Ben) • some comments seem to rule out MPLS PWs too (Yaakov)

  9. Disadvantage rebuttal • hard to provide QoS assurances w/o co p2p trail • QoS similar to LDP based MPLS or L2TP • large number of UDP ports - doesn’t scale • enterprises do not need many PW labels • scales better than VoIP presently being deployed • need protocol for UDP port signaling • can limit to manual provisioning • several simple alternatives (draft-stein-pwe3-udp-00.txt) • UDP checksum introduces processing overhead (Mark) • checksum also useful / may be set to zero • why introduce a new PW type at such a late stage • has been in charter from the beginning • potential security problems • LDP and L2TP protocols are similarly unsafe • potential congestion control problems • similar to L2TP

  10. Proposal • explicitly limit UDP/IP to enterprise (CE-CE) PWs • if present charter is only for SPs then need to update • only allow manual provisioning • enterprise responsible for • security (firewall) • congestion avoidance (admission control) • if the enterprise requires a large number of PWs then MPLS access PWs should be used

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