Network problem within Hyper-V (DNS)
we have small environment, 1 physical server, hosting 4 virtual servers, within hyper-v. experience network problems, ie. connection drops occasionally, causing damaged network packets. problem dns server, unable lookup dns names on internet. network traffic through hyper-v causing problems, traffic between physical server , hardware gateway works fine.
further, more detailed info
the physical server has no problems pinging gateway 10.0.1.1. further, nslookup internet dns server succeeds, fast responses.
only traffic to/from virtual servers, cause problems; running ping on dc/dns server @ 10.0.1.9, makes pings gateway @ 10.0.1.1 succeed, fail. i’ve runned nslookup, locally on virtual dc/dns server, discovered, name lookup attempts, dns server, dns server authoritative, replies fast. however, when dns server has forward query other dns servers on internet, problems occurs.
in nslookup, every time dns query fail, repeating same query 1 or 2 times, makes lookup succeed. have dumps nslookup showing this:
--
> www.microsoft.fr.
server: xxx.intern.xxx.dk
address: 10.0.1.9
------------
sendrequest(), len 34
header:
opcode = query, id = 30, rcode = noerror
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = a, class = in
------------
dns request timed out.
timeout 2 seconds.
timeout (2 secs)
sendrequest failed
------------
sendrequest(), len 34
header:
opcode = query, id = 31, rcode = noerror
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = aaaa, class = in
------------
------------
got answer (61 bytes):
header:
opcode = query, id = 31, rcode = noerror
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = aaaa, class = in
answers:
-> www.microsoft.fr
type = cname, class = in, dlen = 15
canonical name = m110.pictime.fr
ttl = 86398 (23 hours 59 mins 58 secs)
------------
*** request xxx.intern.xxx.dk timed-out
> www.microsoft.fr.
server: xxx.intern.xxx.dk
address: 10.0.1.9
------------
sendrequest(), len 34
header:
opcode = query, id = 32, rcode = noerror
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = a, class = in
------------
------------
got answer (77 bytes):
header:
opcode = query, id = 32, rcode = noerror
header flags: response, want recursion, recursion avail.
questions = 1, answers = 2, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = a, class = in
answers:
-> www.microsoft.fr
type = cname, class = in, dlen = 15
canonical name = m110.pictime.fr
ttl = 86393 (23 hours 59 mins 53 secs)
-> m110.pictime.fr
type = a, class = in, dlen = 4
internet address = x.x.x.x
ttl = 1193 (19 mins 53 secs)
------------
non-authoritative answer:
------------
sendrequest(), len 34
header:
opcode = query, id = 33, rcode = noerror
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional = 0
questions:
www.microsoft.fr, type = aaaa, class = in
------------
------------
got answer (117 bytes):
header:
opcode = query, id = 33, rcode = noerror
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 1, additional = 0
questions:
www.microsoft.fr, type = aaaa, class = in
answers:
-> www.microsoft.fr
type = cname, class = in, dlen = 15
canonical name = m110.pictime.fr
ttl = 86393 (23 hours 59 mins 53 secs)
authority records:
-> pictime.fr
type = soa, class = in, dlen = 36
ttl = 1195 (19 mins 55 secs)
primary name server = edison.pictime.fr
responsible mail addr = root.pictime.fr
serial = 2008110707
refresh = 600 (10 mins)
retry = 600 (10 mins)
expire = 3600000 (41 days 16 hours)
default ttl = 1200 (20 mins)
------------
name: m110.pictime.fr
address: 193.238.151.9
aliases: www.microsoft.fr
--
my discoveries indicate, dns server works correctly, networking through hyper-v unstable.
when executed on on 1 of other virtual machines, pings hardware gateway @ 10.0.1.1 work fine. nslookups towards internet dns servers work fine. however, dns queries against local dns server @ 10.0.1.9 fail. again, seems local dns server has problems forwarding dns queries internet.
yesterday tried these steps, without luck:
- changed virtual nic on virtual server running dns. removed synthetic hyper-v nic, ip 10.0.1.10, , added legacy network adapter, new address of 10.0.1.9. , of course modified dns server address on remaining virtual servers.
- upgraded drivers both intel nics , broadcom nics.
- disabled large send offload v2 (ipv4) on physical intel nic …but same behavior before. the setup this: physical setup. one physical server: virtual environment within hyper-v: 4 virtual servers: hyper-v has created 2 virtual nics, on host server, 1 of these in use. 1 in use, connected physical nic #4, that’s connected gateway router. ip addresses virtual machines:
a dell power edge 2950, running windows server 2008 x64 hyper-v. no antivirus.
nic information:
this physical server has 6 nics (4 intel pro/1000 pt dual port server adaptors, , 2 broadcom bcm5708c netxtreme ii gige). 1 of 6 nics in use, it’s 1 of intel nics, intel nic #4, connected hardware firewall/nat router, connects internet.
ip addresses:
- intel nic that’s in use: 10.0.1.5 (this address has been taken on 1 of hyper-vs virtual nics)
- the hardware firewall/nat router: 10.0.1.1. network connection physical server.
running windows server 2008 x64. each has 1 virtual nic. virtual nics connected physical nic that’s in use.
10.0.1.9: domain controller, dns server, ts license server
10.0.1.11: sql server
10.0.1.12: exchange 2007
10.0.1.13: terminal server
it seems people experienced problems beta releases. have problem in finan version. clue on how resolve problem? have send problem microsoft support did tell not bog configuration error , invoiced us. seems doing wrong here. what?
we found disabling tcp/offload engine on network cards fix issue
do have packet losts on network?
are sure switch not causing problem ?
Windows Server > Hyper-V
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