starvation line vty Virtual Exec

Unanswered Question
Nov 30th, 2009

Hi,

I'am have a problem with 7606 router. My script over rcp upload access-list to the running-conf.

Today i'am see that

router# systat
    Line       User       Host(s)              Idle       Location
   1 vty 0                Virtual Exec         00:00:00

on 2 routers have this process.

My script at that time not work,

rcp -4 test.acl [email protected]:running-config
rcp: lost connection

and i'am try upload config over tftp:

copy tftp running-config
Address or name of remote host [xxx.xxx.xxx.xxx]?
Source filename [as-saargate.prf]?
Destination filename [running-config]?
Accessing tftp://xxx.xxx.xxx.xxx/test.acl...
Loading as-saargate.prf from xxx.xxx.xxx.xxx (via Vlan740): !
[OK - 189 bytes]

%Error opening system:/running-config (Device or resource busy)

Guru say please,

how clear Virtual Exec session?

Cle line 1 don't help, line busy

I have this problem too.
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yjdabear Mon, 11/30/2009 - 09:01

What version of IOS is this?

Sounds like you either have to reload or try the tip at the end of this doc:

http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2ae4.shtml

"A hung telnet session leads to a high CPU due to the Virtual Exec process. In order to clear the hung telnet session, the device needs to be reloaded in most cases. The other way to clear the hung telnet session is to clear the TCP process. The TCP process can be identified with the command show tcp brief as in this output:

Router#show tcp brief
TCB       Local Address           Foreign Address        (state)
02FA62D0  172.16.152.75.23        dhcp-171-69-104-.3013  ESTAB

From the above output, the TCP process 02FA62D0 needs to be cleared in order to clear the hung telnet session with the command clear tcp tcb 0x02fa62d0 "

Vadim_hoster Mon, 11/30/2009 - 23:52

#show tcp vty 0

empty output (

ios (c7600s72033_rp-ADVENTERPRISEK9-M), Version 12.2(33)SRD3

commmand show tcp brief

show me all of the working tcp sessions. but session that was buzz not present.

Vadim_hoster Wed, 12/02/2009 - 08:44

Hi,

also we have same problem on CAT-6506, SUP-720XL

IOS: Cisco IOS Software, s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(33)SXH3a

May be you know other  way, how it better manipulate config in routers?

We need dynamicaly update prefix list and acl filters.

Thank you!

yjdabear Wed, 12/02/2009 - 09:34

Your IOS versions seem new enough to take advantage of "Configuration Replace and Configuration Rollback" without having to reboot. Specifically,

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t7/feature/guide/gtrollbk.html

"Configuration Replace

The configure replace command provides the capability to replace the current running configuration with any saved Cisco IOS configuration file. This functionality can be used to revert to a previous configuration state, effectively rolling back any configuration changes that were made since the previous configuration state was saved. "

So, instead of replacing the running-config with an older version, maybe you could point it to a newer copy (with new prefix and ACL) on your TFTP/RCP/FTP/SCP server, say "configure replace ftp://10.10.10..50/my-new-config.txt".

The traditionial "copy tftp running" cannot pull it off because it merges, while "copy tftp start" overwrites but requires reloading.

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