On Thu, 30 Sep 2004, John Brown CT wrote:
> Couple of points here.
>
> 1. Typical DNS queries are via UDP, not TCP.
> Thus the noise Dean is making here about things breaking
> because of TCP issues, is well noise.
Noise about TCP, yes.
> Keep in mind that DNS queries are UDP. The query and the response.
> so a typical query is 2 packets, the ask and the answer.
>
> Having DNS be based on TCP would NOT scale very well.
We know. As you point out, TCP is still used.
> Think about
> it. Before I could even make a query I would have to deal with
> at least 3 packets for the TCP connection setup. Then I'd send my
> query, which would also have an TCP ACK sent as well, oh then there
> is the answer to the query, with yet another TCP ACK. So a single
> DNS query would (at a min) take 7 packets, more likely 8 to 10,
> thats 400 to 500 percent more traffic than via UDP.
We know. But people still propose things that will take big packets or
DNSSEC, etc.
> DNS uses TCP in special cases. Some of them, but not all of them
> are. 1. Packet size, 2. AXFR, 3. I think TSIG / DNS SeC stuff
>
> Now before Dean jumps on the See, AXFR is broke, lets understand that
> AXFR doesn't happen for anycasted root servers on their PUBLIC facing
> IP address. AXFR is typically going to happen on a globally unique
> IP assigned to each specific Anycast'd host. Thus TCP works just
> fine.
Yes, I'll accept that roots can be updated via means other than AXFR and
updated via other than anycasted IP addresses.
>
> 2. This "single router requirement" is an interesting comment. I've not
> seen this in any RFC or BCP. Is there one ?? I'd hope not.
A BCP/RFC for what? You mean anycast? I don't know if it is in the RFC
describing anycast. However, that is obviously a requirement, as pointed
out previously by others.
> Having muliple routers in a mesh format is good. That means if one
> router fails the other can take the traffic.
No doubt.
> Keep in mind that from a packet path forwarding decision process,
> these routers are speaking other protocols as well. There is dynamic
> information being shared between these closely coupled routers that
> lets them do the right thing.
Really? And what protocols are those?
--Dean
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