| To: | nv-l@lists.tivoli.com |
|---|---|
| Subject: | RE: What happened to netmon Flag? |
| From: | Sean Davidson <sean.davidson@mail.publix.com> |
| Date: | Fri, 7 Jul 2000 10:37:34 -0400 |
This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. The loopback interface on a Cisco router and the loopback interface on a standard TCP/IP machine (127.0.0.1) are two different things. The loopback on a standard TCP/IP machine is typically used for communication between processes on that machine. So a 255.255.255.255 mask is valid. The loopback interface on a Cisco router is a software interface that only drops when it is either intentionally shutdown or the router loses power. Other than that, it is a just like any other interface on the router. You have to give it a valid IP address with a valid subnet mask. 255.255.255.255 (network of all 1's) is never a valid TCP/IP subnet mask. There are no bits left over for hosts. The loopback interface on the cisco router is typically used to tie Cisco processes like DLSW,RSRB,BSTUN,STUN,etc... If you have a primary and backup link on a router and you tie any of those processes to a real physical interface, that process no longer functions when the primary interface goes down and the backup link recovers the connectivity. This is where the Cisco loopback interface is useful. It is always up. I don't believe the -L netmon flag you mention is the problem. Check the MIB2 interface table reported by the router and see if the loopback interface is there. __________________________ Thanks, Sean Davidson Sr. Network Systems Engineer Publix Super Markets, Inc. P.O. Box 32015 Lakeland, Fl. 33802-2015 Email - sean.davidson@publix.com Voice - (863) 686-8754 x6889 Fax - (863)616-5895 -----Original Message----- From: Kuffer Andreas [mailto:Andreas.Kuffer@kuoni.ch] Sent: Friday, July 07, 2000 3:48 AM To: 'IBM NetView Discussion' Subject: RE: [NV-L] What happened to netmon Flag? I checked the netmask of the loopback interface, it was indeed set to 255.255.255.252. I asked the network guys why and the answer was that in earlier times you were not allowed (unable) to set a mask of 255.255.255.255. So the "loopback-netmask"-design of our network is 255.255.255.252 due to historical reasons. Anyway we reconfigured the Cisco 1600 to 255.255.255.255, did a demand poll and also a new discovery but received the same results as I posted before. I will call support today but I'm still interested if there is anybody out there with NetView 6.0 discovering loopback interfaces. With kind regards / mit freundlichen Gruessen Andreas Kuffer (System Manager UNIX and Enterprise Management) -----Original Message----- From: lclark@us.ibm.com [ mailto:lclark@us.ibm.com <mailto:lclark@us.ibm.com> ] Sent: Donnerstag, Juli 06, 2000 16:30 To: IBM NetView Discussion Subject: Re: [NV-L] What happened to netmon Flag? The -L flag was dropped in V6 (made a no-op) because it was no longer needed. This is because, according to the internal update I attended, 32-bit masks are now fully supported; 32-bit masks are generally used for software loopback interfaces. The connection is not exactly clear to me, but I have seen loopbacks discovered successfully in V6, whether the loopback was the address specified in the seedfile or not. So by my voodoo-problem-determination methodology, I would suggest checking the mask on the loopback that is missing. If it is not 255.255.255.255, make it so. If it is already so, look for some other, more mundane discovery problem, or call Support with a trace of the discovery handy. Cordially, Leslie A. Clark IBM Global Services - Systems Mgmt & Networking Detroit Kuffer Andreas <Andreas.Kuffer@kuoni.ch>@tkg.com on 07/06/2000 04:59:40 AM Please respond to IBM NetView Discussion <nv-l@tkg.com> Sent by: owner-nv-l@tkg.com To: "'IBM NetView Discussion'" <nv-l@tkg.com> cc: Subject: [NV-L] What happened to netmon Flag? AIX 4.3.2, NV 5.1.2 and NV 6.0 in version 6.0 of netview it seems that one flag of netmon (-L, discover loopback interfaces with other address than 127.0.0.0) was withdrawn. I have a Cisco 1600 with loopback interface 10.10.224.85 and three other interfaces Demand poll with NV 5.1.2 (netmon runs with -L): Interface 10.10.232.86 (currently up) responded to ping Interface 10.10.21.1 (currently up) responded to ping Interface 10.10.224.85 (currently up) responded to ping Interface 10.10.240.86 (down since 07/03/00) ping timed out Demand poll with NV 6.0 shows: Interface 10.10.232.86 (currently up) responded to ping Interface 10.10.21.1 (currently up) responded to ping Interface 10.10.240.86 (down since 07/03/00) ping timed out So it looks like netmon V6.0 doesn't discover the loopback interface I'd like to see. Does that work as designed? Did I miss anything? Can I use an undocumented "-L feature"? Any help is very welcome...Andreas With kind regards / mit freundlichen Gruessen Andreas Kuffer (System Manager UNIX and Enterprise Management) Kuoni Travel Ltd. Dep. TOU Neue Hard 7 CH-8010 Zuerich Switzerland Telefon : + 41 1 277 52 41 Fax : + 41 1 272 52 55 <<< the smile that you send out returns to you >>> _________________________________________________________________________ NV-L List information and Archives: http://www.tkg.com/nv-l <http://www.tkg.com/nv-l> The
loopback interface on a Cisco router and the loopback interface on a standard
TCP/IP machine (127.0.0.1) are two different things. The loopback on a standard
TCP/IP machine is typically used for communication between processes on that
machine. So a 255.255.255.255 mask is valid.
The
loopback interface on a Cisco router is a software interface that only drops
when it is either intentionally shutdown or the router loses power. Other than
that, it is a just like any other interface on the router. You have to give it a
valid IP address with a valid subnet mask. 255.255.255.255 (network of all 1's)
is never a valid TCP/IP subnet mask. There are no bits left over for hosts. The
loopback interface on the cisco router is typically used to tie Cisco processes
like DLSW,RSRB,BSTUN,STUN,etc...
If you
have a primary and backup link on a router and you tie any of those
processes to a real physical interface, that process no longer functions when
the primary interface goes down and the backup link recovers the connectivity.
This is where the Cisco loopback interface is useful. It is always
up.
I
don't believe the -L netmon flag you mention is the problem. Check the MIB2
interface table reported by the router and see if the loopback interface is
there.
__________________________ Sr. Network Systems
Engineer
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