RE: Telnet and mail problems [7:392]
I would have to conclude (with the little info provided) that you are experiencing a reverse lookup problem. Check your DNS (internal and external) and make sure that the right address/resolution/name is in order. Moe. -Original Message- From: Luis Oliveira [mailto:[EMAIL PROTECTED]] Sent: Thursday, April 12, 2001 1:27 PM To: [EMAIL PROTECTED] Subject: Telnet and mail problems [7:392] Fellow Cisco users This is my first post to the list. I've been watching the list for messages regarding a problem that we have at my company (newspaper business) that's probably related to our new network. We have recently changed for a new building and since we are now placed in several floors (as opposed to the situation we had before) we have taken this opportunity to build a new network infrastructure. We have a central Cisco Catalyst 6006 with 48 10/100 mbit ports, 2*8 fiber optic modules that connect to 5 floors (Cisco 3548 XL and Cisco 3524 switches) by fiber cable. We have a relatively large network of 400 machines (80% Macs, 20% PC's) divided by VLAN's. We also have 30 or so servers (ranging from Sun Solaris running Sybase, to Windows NT 4 and 2000 file servers, Microsoft SQL servers, Appleshare File servers, AIX machines running Oracle, etc. Our machines have fixed IP addresses. We are experimenting a problem when we try to telnet a Unix machine. It takes forever (almost half a minute). The same problem with e-mail checking ( 30 seconds to logon on the server). Before we had just two subnets. Now we have more (private networks), and the mail server is on a public network (DMZ) separated from us by a firewall. We think that the problem is related with the Ciscos or the implementation of the VLAN's. The company that implemented our network (which is a sister company of my company) until now as not found a solution to our problem and the mail users, which is everyone is becoming very upset with all this. Everything else works fine on the network works fine (copying files, browse the internet, that kind of stuff). Anyone have seen this kind of trouble before ? Can give some advice or steps to follow to eliminate this ? Sorry for the long post. Thanks // luis oliveira FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=395&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Telnet and mail problems [7:392]
Hi The first thing I would look at is name resolution. UNIX/Linux systems (telnet and email especially) both use reverse lookup. If the UNIX/Linux box can not find a name to go with the IP it will produce the situation you describe. As a quick experiment, add a host to the hosts file on the UNIX box you are telneting to. Then telnet to it from that host, I'll bet the connect is very fast. You can do the same for POP3/SMTP. HTH -- John Hardman CCNP MCSE ""Luis Oliveira"" wrote in message news:[EMAIL PROTECTED]... > Fellow Cisco users > > This is my first post to the list. I've been watching the list for messages > regarding a problem that we have at my company (newspaper business) that's > probably related to our new network. > > > We have recently changed for a new building and since we are now placed in > several floors (as opposed to the situation we had before) we have taken > this opportunity to build a new network infrastructure. > > We have a central Cisco Catalyst 6006 with 48 10/100 mbit ports, 2*8 fiber > optic modules that connect to 5 floors (Cisco 3548 XL and Cisco 3524 > switches) by fiber cable. > > We have a relatively large network of 400 machines (80% Macs, 20% PC's) > divided by VLAN's. We also have 30 or so servers (ranging from Sun Solaris > running Sybase, to Windows NT 4 and 2000 file servers, Microsoft SQL > servers, Appleshare File servers, AIX machines running Oracle, etc. > > Our machines have fixed IP addresses. We are experimenting a problem when we > try to telnet a Unix machine. It takes forever (almost half a minute). The > same problem with e-mail checking ( 30 seconds to logon on the server). > Before we had just two subnets. Now we have more (private networks), and the > mail server is on a public network (DMZ) separated from us by a firewall. We > think that the problem is related with the Ciscos or the implementation of > the VLAN's. The company that implemented our network (which is a sister > company of my company) until now as not found a solution to our problem and > the mail users, which is everyone is becoming very upset with all this. > Everything else works fine on the network works fine (copying files, browse > the internet, that kind of stuff). > > Anyone have seen this kind of trouble before ? Can give some advice or steps > to follow to eliminate this ? > > > Sorry for the long post. > > > Thanks > > > > // luis oliveira > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=396&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Telnet and mail problems [7:392]
We have seen this when servers' DNS server entries are incorrect / unreachable. Thanks! TJ -Original Message- From: Luis Oliveira [mailto:[EMAIL PROTECTED]] Sent: Thursday, April 12, 2001 16:27 To: [EMAIL PROTECTED] Subject:Telnet and mail problems [7:392] Fellow Cisco users This is my first post to the list. I've been watching the list for messages regarding a problem that we have at my company (newspaper business) that's probably related to our new network. We have recently changed for a new building and since we are now placed in several floors (as opposed to the situation we had before) we have taken this opportunity to build a new network infrastructure. We have a central Cisco Catalyst 6006 with 48 10/100 mbit ports, 2*8 fiber optic modules that connect to 5 floors (Cisco 3548 XL and Cisco 3524 switches) by fiber cable. We have a relatively large network of 400 machines (80% Macs, 20% PC's) divided by VLAN's. We also have 30 or so servers (ranging from Sun Solaris running Sybase, to Windows NT 4 and 2000 file servers, Microsoft SQL servers, Appleshare File servers, AIX machines running Oracle, etc. Our machines have fixed IP addresses. We are experimenting a problem when we try to telnet a Unix machine. It takes forever (almost half a minute). The same problem with e-mail checking ( 30 seconds to logon on the server). Before we had just two subnets. Now we have more (private networks), and the mail server is on a public network (DMZ) separated from us by a firewall. We think that the problem is related with the Ciscos or the implementation of the VLAN's. The company that implemented our network (which is a sister company of my company) until now as not found a solution to our problem and the mail users, which is everyone is becoming very upset with all this. Everything else works fine on the network works fine (copying files, browse the internet, that kind of stuff). Anyone have seen this kind of trouble before ? Can give some advice or steps to follow to eliminate this ? Sorry for the long post. Thanks // luis oliveira FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] * The information in this email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this email are subject to the terms and conditions expressed in the governing KPMG client engagement letter. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=397&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Telnet and mail problems [7:392]
At 04:27 PM 4/12/01 -0400, Luis Oliveira wrote: >Our machines have fixed IP addresses. We are experimenting a problem when we >try to telnet a Unix machine. It takes forever (almost half a minute). The >same problem with e-mail checking ( 30 seconds to logon on the server). >Before we had just two subnets. Now we have more (private networks), and the >mail server is on a public network (DMZ) separated from us by a firewall. We >think that the problem is related with the Ciscos or the implementation of >the VLAN's. The company that implemented our network (which is a sister >company of my company) until now as not found a solution to our problem and >the mail users, which is everyone is becoming very upset with all this. >Everything else works fine on the network works fine (copying files, browse >the internet, that kind of stuff). > >Anyone have seen this kind of trouble before ? Can give some advice or steps >to follow to eliminate this ? > >Sorry for the long post. > >Thanks > >// luis oliveira Hm. It sounds a lot like DNS issues. Do you have guys pointing to an internal DNS server? Does your mail server resolve to an internal IP? If you do internal DNS, I can see where you might have "inside has problems", "outside is dandy" problems. Can you time the telnetting to the Unix box? Are you sure it is not 75 seconds? (If it is, it is almost definitely DNS issues). Have you tried doing "ping" floods to those hosts just to see what % of packet loss occurs, if any? It could very well be other issues, but check your DNS setups to see if anything seems fishy with your internal DNS. -Carroll Kong Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=399&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Telnet and mail problems [7:392]
Should the logon time be so long even if I telnet by numeric address, say telnet xx.yy.zz.ww ? Regards // luis oliveira > At 04:27 PM 4/12/01 -0400, Luis Oliveira wrote: > >> Our machines have fixed IP addresses. We are experimenting a problem when we >> try to telnet a Unix machine. It takes forever (almost half a minute). The >> same problem with e-mail checking ( 30 seconds to logon on the server). >> Before we had just two subnets. Now we have more (private networks), and the >> mail server is on a public network (DMZ) separated from us by a firewall. We >> think that the problem is related with the Ciscos or the implementation of >> the VLAN's. The company that implemented our network (which is a sister >> company of my company) until now as not found a solution to our problem and >> the mail users, which is everyone is becoming very upset with all this. >> Everything else works fine on the network works fine (copying files, browse >> the internet, that kind of stuff). >> >> Anyone have seen this kind of trouble before ? Can give some advice or steps >> to follow to eliminate this ? >> >> Sorry for the long post. >> >> Thanks >> >> // luis oliveira > > Hm. It sounds a lot like DNS issues. Do you have guys pointing to an > internal DNS server? Does your mail server resolve to an internal IP? If > you do internal DNS, I can see where you might have "inside has problems", > "outside is dandy" problems. Can you time the telnetting to the Unix > box? Are you sure it is not 75 seconds? (If it is, it is almost > definitely DNS issues). Have you tried doing "ping" floods to those hosts > just to see what % of packet loss occurs, if any? It could very well be > other issues, but check your DNS setups to see if anything seems fishy with > your internal DNS. > > -Carroll Kong Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=402&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Telnet and mail problems [7:392]
At 05:31 PM 4/12/01 -0400, Luis Oliveira wrote: >Should the logon time be so long even if I telnet by numeric address, say >telnet xx.yy.zz.ww ? > > > >Regards > > >// luis oliveira Absolutely. Sorry I was not as clear as the others, it is because the unix boxes will try to do a reverse DNS lookup on the incoming connection. Usually this is because they use tcp_wrappers and / or they log the connections? In general, you want to always have a fully resolvable network, both forwards and backwards. So whoever the host that is trying to connect to the Unix box, if the host's IP does not reverse properly, you can expect such issues. The issue is not so much that your forward dns is not working, since if you do it by IP, there is no forward dns resolution being done at all. But the unix box will try to reverse the incoming IP. -Carroll Kong Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=407&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Telnet and mail problems [7:392]
~30 seconds or so is within reason ... Thanks! TJ -Original Message- From: Luis Oliveira [mailto:[EMAIL PROTECTED]] Sent: Thursday, April 12, 2001 17:31 To: [EMAIL PROTECTED] Subject:Re: Telnet and mail problems [7:392] Should the logon time be so long even if I telnet by numeric address, say telnet xx.yy.zz.ww ? Regards // luis oliveira > At 04:27 PM 4/12/01 -0400, Luis Oliveira wrote: > >> Our machines have fixed IP addresses. We are experimenting a problem when we >> try to telnet a Unix machine. It takes forever (almost half a minute). The >> same problem with e-mail checking ( 30 seconds to logon on the server). >> Before we had just two subnets. Now we have more (private networks), and the >> mail server is on a public network (DMZ) separated from us by a firewall. We >> think that the problem is related with the Ciscos or the implementation of >> the VLAN's. The company that implemented our network (which is a sister >> company of my company) until now as not found a solution to our problem and >> the mail users, which is everyone is becoming very upset with all this. >> Everything else works fine on the network works fine (copying files, browse >> the internet, that kind of stuff). >> >> Anyone have seen this kind of trouble before ? Can give some advice or steps >> to follow to eliminate this ? >> >> Sorry for the long post. >> >> Thanks >> >> // luis oliveira > > Hm. It sounds a lot like DNS issues. Do you have guys pointing to an > internal DNS server? Does your mail server resolve to an internal IP? If > you do internal DNS, I can see where you might have "inside has problems", > "outside is dandy" problems. Can you time the telnetting to the Unix > box? Are you sure it is not 75 seconds? (If it is, it is almost > definitely DNS issues). Have you tried doing "ping" floods to those hosts > just to see what % of packet loss occurs, if any? It could very well be > other issues, but check your DNS setups to see if anything seems fishy with > your internal DNS. > > -Carroll Kong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] * The information in this email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this email are subject to the terms and conditions expressed in the governing KPMG client engagement letter. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=409&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Telnet and mail problems [7:392]
Yes. It has nothing to do with what address/name you are telneting to. It has everything to do with the IP/Name of the host you are telneting from. UNIX/Linux trys to do a reverse lookup on IP addresses for logging and other reasons. It will not "complete" the telnet session, e.g. present you with login: prompt until it times out the reverse resolve. Try the test I posted before, it takes only a couple of minutes and is definitive as it being a DNS reverse resolve problem or not. HTH -- John Hardman CCNP MCSE ""Luis Oliveira"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Should the logon time be so long even if I telnet by numeric address, say > telnet xx.yy.zz.ww ? > > > > Regards > > > // luis oliveira > > > > > At 04:27 PM 4/12/01 -0400, Luis Oliveira wrote: > > > >> Our machines have fixed IP addresses. We are experimenting a problem when > we > >> try to telnet a Unix machine. It takes forever (almost half a minute). The > >> same problem with e-mail checking ( 30 seconds to logon on the server). > >> Before we had just two subnets. Now we have more (private networks), and > the > >> mail server is on a public network (DMZ) separated from us by a firewall. > We > >> think that the problem is related with the Ciscos or the implementation of > >> the VLAN's. The company that implemented our network (which is a sister > >> company of my company) until now as not found a solution to our problem > and > >> the mail users, which is everyone is becoming very upset with all this. > >> Everything else works fine on the network works fine (copying files, > browse > >> the internet, that kind of stuff). > >> > >> Anyone have seen this kind of trouble before ? Can give some advice or > steps > >> to follow to eliminate this ? > >> > >> Sorry for the long post. > >> > >> Thanks > >> > >> // luis oliveira > > > > Hm. It sounds a lot like DNS issues. Do you have guys pointing to an > > internal DNS server? Does your mail server resolve to an internal IP? If > > you do internal DNS, I can see where you might have "inside has problems", > > "outside is dandy" problems. Can you time the telnetting to the Unix > > box? Are you sure it is not 75 seconds? (If it is, it is almost > > definitely DNS issues). Have you tried doing "ping" floods to those hosts > > just to see what % of packet loss occurs, if any? It could very well be > > other issues, but check your DNS setups to see if anything seems fishy with > > your internal DNS. > > > > -Carroll Kong > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=418&t=392 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
