>From the title of this draft, it only serves the dual-stack lite scenario. For support generic tunnel scenarios, we have recently proposed a new draft draft-guo-softwire-sc-discovery http://tools.ietf.org/html/draft-guo-softwire-sc-discovery-00 to softwire WG. It proposes a general softwire (tunnel) concentrator discovery mechanism. It is generic to server different kinds of tunnel/softwire concentrator auto discover scenarios includes the scenario of draft-dhankins-softwire-tunnel-option.
Regards, Sheng > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tomasz Mrugalski > Sent: Monday, June 29, 2009 7:55 AM > To: [email protected] > Subject: [Softwires] A few > draft-dhankins-softwire-tunnel-option-03 comments > > > Hi, > I've read draft-dhankins-softwire-tunnel-option-03 draft > recently and have several comments and questions: > > 1. Tunnel type > Can we assume that IPv4-over-IPv6 will be the only tunnel type used? > I think not. Therefore tunnel-type field should be added to > the DS_LITE option. One octet is enough. > > 2. SI hints > I think it should be possible (or even recommended) that > client will send not only OPTION_DS_LITE in ORO, but also MAY > provide OPTION_DS_LITE itself in SOLICIT, REQUEST, RENEW, > etc. messages. It should contain address of previously used > SC address, provided as a hint to the DHCPv6 server. Here's > scenario, where this approach could be useful: > > Network Operator may have more than one SC. It is reasonable > to assume that client-to-SC assignment will not be fixed, but > rather client will be assigned to a SC (e.g. due to load-balancing). > > Using knowledge about previously used SC, Network Operator > may prefer to assign this particular client to the same SC as > before. There are several benefits of such assignment. In > particular, if SI was reboot, some enc-user sessions may > still be active. > > 3. Preference > In section 3, multihoming is mentioned. Would it be > beneficial to provide additional field in the option called > Tunnel preference? Its meaning would be similar to the one in > DHCPv6's PREFERENCE option. In case when multihoming device > has several softwire offers, it would use (or favor) the one > with highest preference. The best size for this field would > be 1 octet. > > 4. Renewal > According to Softwire Problem Statement (RFC4925), section > 1.1, softwires are generally dynamic. Shouldn't SC address be > periodically renewed? This would be useful for graceful > failover to a different SC. There are several possible solutions: > a) Include current SC address in all RENEW messages, using > DS_LITE_OPTION. > (poor choice, renewal frequency depends on leased address and > prefix T1 values) > b) use Information Refresh Time Option (RFC4242) to define how often > DS_LITE option should be renewed. > c) add T1 (and possibly T2) to the DS_LITE option, with > meaning similar to > T1 and T2 used in IA_NA and IA_PD options. > > Another issue is related to the following question: Is > softwire permanent? > Can we assume that softwire is permanent in the sense that > once established, it will be used and is valid until SI > crashes or is powered off? What about failover scenarios when > SC malfunctions or reaches end of its lifecycle? Maybe it > would be useful to specify lifetime? This counter could be > reset every time DS_LITE option is renewed, exactly the same > as addresses in IA_NA option. > > Size of those fields (T1,T2, lifetime) would be standard > double words and values expressed in seconds. > > 5. Softwire termination > Again, Softwire Problem Statement (RFC4925), Section 1.1 > states that softwires may be initiated and terminated on > demand. How should SI release its tunnel? Assuming that > softwire tunnel is teared down once SI sends Release message > is not appropriate. I think the simplest approach is the > best: SI should include OPTION_DS_LITE in the RELEASE > message. Server may acknowledge this by sending DS_LITE > option with address set to ::. This could be used to notify > SC that it may free its resources associated with tunnel for > this particular SI. > > 6. Stateless autoconfiguration > DS_LITE on its own, without address being delegated, is > useless. I think clarification should be added that this > option may not be used in stateless DHCPv6 (i.e. is not > allowed in INFORMATION-REQUEST message). > > 7. Leasequery > There's a mechanism for querying server about provided > configuration parameters (RFC5007). Would it be useful for a > server to report that DS_LITE option was provided to the > client in question? I'm not sure if such details should be > put in the draft or not. > > I think that's it for now. That's my first post on IETF, so > forgive me if I was pointing out the obvious or discussing > topic already covered (I've checked list archives, but I > could have missed something). > > Regards, > -- > Tomasz Mrugalski Dibbler - a portable DHCPv6 > implementation > [email protected] http://klub.com.pl/dhcpv6/ > Gdansk University of Technology > _______________________________________________ > Softwires mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/softwires _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
