Cisco Cisco IOS Software Releases 12.2 MC Notas de publicación
15
Release Notes for Cisco MGX-RPM-1FE-CP Back Card for Cisco IOS Release 12.2(15)MC2c
OL-2920-08
Troubleshooting
Troubleshooting
This section contains the following MGX-RPM-1FE-CP troubleshooting information:
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Collecting Data for Back Card and Router Issues
To collect data for reporting back card and router issues, issue the following commands:
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show tech-support—Displays general information about the router when it reports a problem.
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show logging—Displays information in the syslog history table.
Modifying the MLP Reorder Buffer
When PPP multiplexing is disabled on the inbound direction of a MWR 1941-DC multilink, there are
many more packets to reorder. Therefore, we recommend that you modify the MLP reorder buffer using
the ppp multilink slippage interface configuration commands to avoid discarded fragments due to
buffer overflow.
many more packets to reorder. Therefore, we recommend that you modify the MLP reorder buffer using
the ppp multilink slippage interface configuration commands to avoid discarded fragments due to
buffer overflow.
Slippage is the amount by which data arriving on one link in a multilink bundle might lag behind data
transmitted over another link in that bundle. The amount of slippage might be expressed as a direct byte
count, but it is also commonly expressed as a measure of time, in terms of the differential delay between
the links.
transmitted over another link in that bundle. The amount of slippage might be expressed as a direct byte
count, but it is also commonly expressed as a measure of time, in terms of the differential delay between
the links.
A small amount of slippage between links is normal. Whenever slippage occurs, the multilink input
process must buffer fragment data arriving on the faster channels until it receives all expected fragments
on the remaining links, so that it can sort the fragments back into proper order, reassemble datagrams as
necessary, and then deliver the datagrams in proper order to the higher network layers (multilink
fragments include sequence numbers so that the multilink receiver can readily detect when packets are
arriving out of order). The receiver must be capable of buffering enough data to compensate for normal
slippage between the links, otherwise it will be incapable of completely sequencing and reassembling
datagrams, and some data will be lost.
process must buffer fragment data arriving on the faster channels until it receives all expected fragments
on the remaining links, so that it can sort the fragments back into proper order, reassemble datagrams as
necessary, and then deliver the datagrams in proper order to the higher network layers (multilink
fragments include sequence numbers so that the multilink receiver can readily detect when packets are
arriving out of order). The receiver must be capable of buffering enough data to compensate for normal
slippage between the links, otherwise it will be incapable of completely sequencing and reassembling
datagrams, and some data will be lost.
With Cisco IOS Release 12.2(15)MC1 and later, the MLP reorder buffer can be adjusted for cases where
the slippage is larger than the defaults readily accommodate. The buffer size is set by defining a one or
more constraints, each of which indirectly implies some byte limit. The limit used is the maximum of
the value derived from the constraints.
the slippage is larger than the defaults readily accommodate. The buffer size is set by defining a one or
more constraints, each of which indirectly implies some byte limit. The limit used is the maximum of
the value derived from the constraints.
To define the constraints that set the MLP reorder buffer size, issue the following commands while in
interface configuration mode:
interface configuration mode: