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Cisco Bug: CSCtc46361 - c2600: tx-ring-limit command is unavailable under ATM SW SAR PVCs

Last Modified

Jan 30, 2017

Products (1)

  • Cisco 2600 Series Multiservice Platforms

Known Affected Releases

12.3(5.5)T 12.4(15)T10 12.4(25b)

Description (partial)

Consider the following configuration of a T1 (or E1) controller on a VWIC 
installed in a WIC slot of a Cisco 2600 or 2600XM router, set up for ATM with
SoftWare (SW) Segmentation and Reassembly (SAR):

controller T1 0/0
 mode atm
 framing esf
 linecode b8zs
interface ATM0/0
 no ip address
 no atm ilmi-keepalive
interface ATM0/0.100 point-to-point
 ip address
 pvc 0/100 
  vbr-nrt 1536 1536 1
  tx-ring-limit 3

In certain IOS releases, the <CmdBold>tx-ring-limit<noCmdBold> command is not configurable.

This behaviour is observed on Cisco 2600 and 2600XM routers configured for ATM
SW SAR using a T1/E1 VWIC installed in a chassis WIC slot, and using an IOS
specified by or implied by the "First Fixed-in" field of Bug ID CSCec01769 
"LSNT: The tx-ring-limit command on XF sub-intf. is to be blocked."  IOS 
releases from 12.3(7)T onwards through all current 12.4 mainline and 12.4T 
release trains are affected.

The <CmdBold>tx-ring-limit<noCmdBold> command is configurable for ATM PVCs with HardWare (HW) SAR, 
like when using the NM-ATM-4T1 or even when the AIM-ATM and AIM-ATM-VOICE-30
cards are usedd with the same  VWIC in the chassis WIC slot.
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