To:
John Schnizlein <jschnizl@cisco.com>
Cc:
Soohong Daniel Park <soohong.park@samsung.com>, dnsop@cafax.se
From:
Bob Hinden <hinden@iprg.nokia.com>
Date:
Wed, 01 Oct 2003 11:19:04 -0700
In-Reply-To:
<4.3.2.7.2.20030929145410.00b1ae48@wells.cisco.com>
Sender:
owner-dnsop@cafax.se
Subject:
Re: How IPv6 host gets DNS address
John, >This apparent efficiency - one packet per link rather than 2 per host - >would come at the cost of the hosts waiting until the next scheduled >multicast RA. Where would the two-packet exchange be more detrimental >than a random delay until DNS is available? The host learns about the router via a Router Advertisement (RA) so having it use the same mechanism to learn the addresses of a DNS server doesn't add any extra delay. Having all the information in one RA seems like a clear win to me as compared to using RAs to learn about routers and link info, and then (perhaps in parallel, but I am not sure about that) have each host use a two packet DHCPv6 exchange to get the addresses of the recursive DNS servers. > >In addition, mobile node (especially WLAN) prefer RA option to DHCP > >from ISP experiences because of below reasons > >1) Delay of DHCP request/reply Relay > >2) Risk of centralized DHCP server (fault, failure and etc.) > >In the circumstance in which RA would suffice, there is no need for >a "centralized DHCP server" or the relay agent to get traffic to it. >The same router that provides RA could answer a DHCPv6 information >request with the options relevant to DNS. Right, if the router was running the DHCPv6 (or DHCPv6 lite) server, then they would have the same fate sharing propriety with the RAs. If it was a centralized DHCPv6 server, then Soohong Park's comment would apply. Bob #---------------------------------------------------------------------- # To unsubscribe, send a message to <dnsop-request@cafax.se>.