Cisco 2600 SERIES 8MB COMPRESSION MODULE Specification Guide
Q. Does Cisco support compression over multi−link PPP?
A. Multi−link PPP with software compression, which includes multi−link PPP with
interleaving plus compression, is supported.
interleaving plus compression, is supported.
Multi−link PPP with hardware compression is supported from Cisco IOS Software Release
12.0(7)T and 12.0(7) on Cisco 7200 and 3600 routers. However, multi−link PPP and
Compression Service Adapter (CSA) are not supported on Cisco 7500 routers.
12.0(7)T and 12.0(7) on Cisco 7200 and 3600 routers. However, multi−link PPP and
Compression Service Adapter (CSA) are not supported on Cisco 7500 routers.
Q. How do you monitor the compression on a link?
A. Issue the show compression command, along with the show interface command, in order
to determine the throughput, the number of compressed packets, and the compression ratio.
to determine the throughput, the number of compressed packets, and the compression ratio.
Troubleshoot Compression
Q. What are the common problems in the implementation of
compression?
compression?
Using software Layer 2 Payload compression, Cisco only supports first−in, first−out
(FIFO) queuing as the packet is compressed prior to presentation to interface queue.
Weighted Fair Queuing is on by default. In order to turn it off you need to issue the
no fair−queue command.
(FIFO) queuing as the packet is compressed prior to presentation to interface queue.
Weighted Fair Queuing is on by default. In order to turn it off you need to issue the
no fair−queue command.
1.
Using hardware Layer 2 Payload compression, Fancy queueing is supported as
packets are queued prior to being compressed thus enabling successful classification.
packets are queued prior to being compressed thus enabling successful classification.
2.
3.
Q. When you attempt to run fast switching and compression, the packets
are process switched. Why?
are process switched. Why?
A. When you run software compression, all packets must go through the processor anyway,
and they are process switched. This is the way compression works.
and they are process switched. This is the way compression works.
Q. When you type "show compress", you receive either no response or
erroneous responses. Why?
erroneous responses. Why?
A. Show compress is broken in earlier versions of Cisco IOS Software Release 12.0 code.
Upgrade to Cisco IOS Software Release 12.0(7) (mainline, S, or T) for the fix (CSCdk15127 (
Upgrade to Cisco IOS Software Release 12.0(7) (mainline, S, or T) for the fix (CSCdk15127 (
registered customers only
) ). This is a cosmetic problem only.
Q. What causes problems when you enable compression between a
Cisco and an Ascend router?
Cisco and an Ascend router?
A. It is a problem with the default configuration on the Ascend box. Contact your Lucent
Technologies Technical Support Representative.
Technologies Technical Support Representative.
Q. When you run Frame Relay payload−compress FRF.9 stac, some
higher−level protocols are compressed, but others are not. Why?
higher−level protocols are compressed, but others are not. Why?
Cisco − WAN Compression FAQs