Hi Max,
I've done some sniffs and traffic does not seem to make it past the
CAS. I see the requests leave the client but they don't seem to go
anywhere, like the CAS is not passing them. I'm planning on doing more
sniffs to try and find out what's going on, just haven't gotten to
them yet.
Another strange wrinkle ... the previous 'bad' IP addresses we had
excluded ... just for kicks, I hard-coded those to a couple of clients
and now they both work perfectly fine. How bizarre. So we get an
occasional bad IP, but it doesn't stay bad forever. That's sounding
more and more like a conflict ...
*Justin Howell*
/Telecommunications Network Technician///
Solano Community College
*From:* Cisco Clean Access Users and Administrators
[mailto:[EMAIL PROTECTED] *On Behalf Of *Caines, Max
*Sent:* Tuesday, April 01, 2008 9:18 AM
*To:* [email protected]
*Subject:* Re: Weird Dead IP Problem
Hi Justin
Have you tried sniffing the network to see what's happening at layer
2? For example, are name lookups working on the client? If no, does
the DNS server see them and respond? If yes, does the CAS see the HTTP
requests and what happens to its responses?
Regards
*Max Caines
IT Services, University of Wolverhampton
Wolverhampton, West Midlands WV1 1SB
Tel: 01902 322245 Fax: 01902 322777*
------------------------------------------------------------------------
*From:* Cisco Clean Access Users and Administrators
[mailto:[EMAIL PROTECTED] *On Behalf Of *Justin Howell
*Sent:* 01 April 2008 16:50
*To:* [email protected]
*Subject:* [CLEANACCESS] Weird Dead IP Problem
OK, here's a strange one, maybe someone's seen this. Our original
CAS setup was one managed subnet, class C, 172.16.6.0/24 to be
exact. Real IP Gateway, In-Band deployment. The untrusted
interface of the CAS and default route for the managed subnet was
172.16.6.1. Over the past two yeara, we would suddenly come up
with a computer that would pull a particular IP, and with that IP,
could not communicate with the CAS or any part of the network; it
was like the IP was blacklisted or in conflict. DNS would not
resolve; if I put in the IP of the CAS, I could get to the login
portal, but when I tried to download the agent, it would timeout.
No other network resources could be accessed, even those allowed
by the unauthenticated role. Cisco of course blamed our network,
that it was an IP problem on our network. Their solution was to
break the managed subnet into two chunks, and exclude the
offending IP. The computer would finally pull a different IP, and
all would be well.
The problem is, this problem keeps happening. It's currently
broken into three different subnet chunks. And now this morning,
we've got another IP that is not communicating with the CAS. The
problem is, with every new chunk made, it requires its own default
gateway; the CAS DHCP pages do not allow me to reuse the existing
gateway. So each 'bad' IP we've got to exclude results in losing
it and another IP for a gateway from our pool. We've got enough
IPs for the moment, but this is getting annoying.
We have another DHCP server for clients not on Clean Access, but
it does not have a pool for the 172.16.6.0 subnet, so
theoretically the only way this problem could be caused by an IP
conflict would be a user on that subnet hard-coding an address.
But they would still be on the clean access subnet, still have to
authenticate/remediate, so I should see them on Users page or the
event logs.
Any one seen this? Or have suggestions? Cisco was not very helpful
last time I called ("Just make two subnets - that IP problem is
your problem not Clean Access's") so I'm hesitant to open another
TAC and spend my week on the phone.
*Justin Howell*
/Telecommunications Network Technician/
Solano Community College
(707) 864-7205
