Dear Qiong, Yes, port ranges can be used in a CGN-based architecture too to reduce log file volume as discussed in http://tools.ietf.org/html/draft-operators-softwire-stateless-4v6-motivation-02#section-3.1.3 but then you should be aware you "loose" a feature offered by the CGN which is:
* The possibility to log the destination IP address for legal storage purposes in case the server does not implement RFC6302. If RFC6302 is largely deployed, then this feature is not needed. There are a lot of trade-offs and there is no universal answers to these trade-offs. Cheers, Med ________________________________ De : Qiong [mailto:[email protected]] Envoyé : mardi 16 août 2011 18:29 À : BOUCADAIR Mohamed OLNC/NAD/TIP Cc : Nejc Škoberne; [email protected]; [email protected] Objet : Re: [Softwires] draft-operators-softwire-stateless-4v6-motivation Hi, Med, and Nejc, Please see inline. You indeed loose agressive sharnig ratio, but you have somewhat more flexible addressing. Also, the CPEs can be then really simple devices, excluding any of the NAPT functionality, doing only stateless encapsulation. However, what you loose/gain is irrelevant for my point. I think this section should be modified in a way like the logging section or any other appropriate way, which explains, that this is not the benefit of the stateless nature, but rather the benefit of the static port allocation. [Qiong]: +1 Agree. Med: Your point is valid and the text should be updated accordingly. My comment aims to show that the comparison is not so that trivial. We can claim the stateful with port ranges can provide similar features as the stateless or the binding mode but we always forget to mention this lead to loose one of the characteristics of the stateful. We captured a similar discussion in http://tools.ietf.org/html/draft-operators-softwire-stateless-4v6-motivation-01#section-4.2: [Qiong]: In our situation, we do not regard aggressive sharing ratio as a vital important feature since the static port multiplex ratio is already enough for us. Besides, even for session-based CGN like ds-lite, we would still prefer to pre-define port-range for customers because our centralized log server can not deal with massive session-based log events. So it seems more reasonable for us to adopt static port arrangement which can largely reduce the log volume. Best regards Qiong Sun "5.2. Port Utilisation Efficiency CGN-based solutions, because they can dynamically assign ports, provide better IPv4 address sharing ratio than stateless solutions (i.e., can share the same IP address among a larger number of customers). For Service Providers who desire an aggressive IPv4 address sharing, a CGN-based solution is more suitable than the stateless. If a Service Provider adopts an aggressive address sharing ratio, it is likely to be attempted by enforcing a NAT port overloading mode and as a consequence some applications will break. However, as more and more hosts become dual-stack enabled, the need for ports in IPv4 is likely to decrease. The insurance to have the full set of 64K ports per host will be one of the incentives to have them IPv6 capable. Moreover, Service Providers should offload some services to IPv6 (e.g., DNS, VoIP)." _______________________________________________ Softwires mailing list [email protected]<mailto:[email protected]> https://www.ietf.org/mailman/listinfo/softwires
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