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
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/ietf