Table Of Contents
Release Notes for Cisco MGX-RPM-1FE-CP Back Card for Cisco IOS Release 12.2(8)MC2d
March 17, 2003
Cisco IOS Release 12.2(8)MC2d
These release notes are for the Cisco MGX-RPM-1FE-CP for Cisco IOS Release 12.2(8)MC2d. These release notes are updated as needed to describe new features, memory requirements, hardware support, software platform deferrals, and changes to the microcode and related documents.
For a list of the software caveats that apply to Cisco IOS Release 12.2(8)MC2d, see the "Caveats in Cisco IOS Release 12.2(8)MC2d" section. To review the release notes for Cisco IOS Release 12.2, go to www.cisco.com and click Technical Documents. Select Release 12.2 from the Cisco IOS Software drop-down menu. Then click Cisco IOS Release Notes > Cisco IOS Release 12.2.
This document contains the following sections:
The MGX-RPM-1FE-CP (one-port, Fast Ethernet-Co-processor) back card is a Cisco MGX 8850 RPM-PR back card that off-loads the following processes from the Route Processor Module (RPM-PR):
•Compression/decompression of Real-time Transport Protocol (RTP)/User Datagram Protocol (UDP) headers (cRTP/cUDP)
•Multiplexing/demultiplexing of Point-to-Point Protocol (PPP) frames
The MGX-RPM-1FE-CP back card is designed to be used with an MGX 8850 that is equipped with one or more RPM-PRs and that terminates some number of T1 lines. Each MGX-RPM-1FE-CP back card has a termination capacity of up to 16 T1s (four per MLP bundle). The MGX-RPM-1FE-CP is only supported with the MLP encapsulation.
The MGX-RPM-1FE-CP back card contains one Fast Ethernet (100Base-Tx) interface. The interface has an RJ45 connector that is used to connect the card to a Category 5 un-shielded twisted pair (UTP) cable. Both half- and full-duplex operation are supported.
MGX-RPM-1FE-CP Back Card in an IP-RAN of a Mobile Wireless Network
The MGX-RPM-1FE-CP back card off loads the compression/decompression of RTP/UDP headers and the multiplexing/demultiplexing of PPP frames.
The supported use of the MGX-RPM-1FE-CP back card is within an IP-RAN of a mobile wireless network. In mobile wireless networks, radio coverage over a geographical space is provided by a network of radios and supporting electronics (Base Transceiver Station or BTS) distributed over a wide area. Each radio and supporting electronics represents a "cell." In traditional networks, the radio signals or radio data frames collected in each cell are forwarded over a T1 (or similar low-speed, leased) line to a centralized Base Station Controller (BSC) where they are processed.
The implementation of the MGX-RPM-1FE-CP backcard in the IP-RAN solution requires the following components:
•Cisco MGX 8850
•MGX-RPM-1FE-CP back card
•BTS router (Cisco MWR 1900 Mobile Wireless Edge Router)
The solution uses OSPF as the routing protocol and requires MLP for transmission of the packets between the aggregation node (MGX8850) and the BTS. It requires you to configure the following:
•The Fast Ethernet (FE) interface to support OSPF. Enable multicast routing and indicate a Protocol Independent Multicast (PIM) mode.
•One or more PPP multilink interfaces with PPP mux and RTP header compression attributes.
•A virtual template for each of the multilink groups.
•A PVC under the switch subinterface that references the virtual template.
In addition, you must configure a connection between the PVC and the FRSM as well as a connection between the FRSM and the PVC.
For detailed information about the MGX-RPM-1FE-CP back card and its implementation in the IP-RAN solution, see the MGX-RPM-1FE-CP Back Card Installation and Configuration Note.
System Configuration Requirements
The MGX-RPM-1FE-CP requires the following system configuration:
•Cisco IOS 12.2(8) MC1 or a later Cisco IOS Release 12.2 MC image is installed on the corresponding Cisco MGX 8850 RPM-PR.
•The FE interface is configured via the Cisco IOS software command line interface.
Table 1 Memory Recommendations for the Cisco MGX 8850 RPM-PR
Platform Software Image Flash
32 MB Flash
256 MB DRAM
Determining the Software Version
To determine the version of Cisco IOS software copied on the RPM-PR, access the CLI of the RPM-PR and enter the show version command:rpm> show versionCisco Internetwork Operating System SoftwareIOS (tm) RPM Software (RPM-JS-M), Version 12.2(8)MC2, EARLY DEPLOYMENT RELEASESOFTWARE (fc1)
Upgrading to a New Software Release
For information about copying Cisco IOS images to RPM-PR Flash memory, see the RPM-PR Installation and Configuration document.
For general information about upgrading to a new Cisco IOS software release, refer to Software Installation and Upgrade Procedures located at the following URL:
New Features in the Cisco IOS Release 12.2 MC Software
The following sections list the new hardware and software features supported by the MGX-RPM-1FE-CP back card for the Cisco IOS Release 12.2MC software releases:
New Features in Cisco IOS Release 12.2(8)MC1
With Cisco IOS Release 12.2(8)MC1, the MGX-RPM-1FE-CP back card supports the following:
•Fast Ethernet—Single 10/100 FE port that can be used with or without cRTP/cUDP or PPP Multiplexing configured.
•cUDP/cRTP—Header compression that compresses UDP/RTP headers to 2 to 4 bytes.
•PPP Multiplexing—Method, as defined in RFC 3153, of sending multiple PPP encapsulated packets in a single PPP frame.
For detailed descriptions of each of these features, see the MGX-RPM-1FE-CP Back Card Installation and Configuration Note.
New Feature in Cisco IOS Release 12.2(8)MC2b
The following new feature is introduced in Cisco IOS Release 12.2(8)MC2b.
Traffic Recovery Over MLP After T1 Failure
When a T1 failure occurs, traffic recovers over the MLP link within 6 seconds.
This caveat is a feature enhancement to the keepalive interface configuration command. With this enhancement, you can also configure a maximum number of retries before a link is declared down by issuing the command as follows:
keepalive [interval] [retries]
•interval is the keepalive interval (in seconds). Valid value is a number greater than 0. The default is 10.
•retries is the number of times a link will be tried again before being declared down. Valid value is a number between 1 and 255. The default is 5.
For implementation in an IP RAN solution, the recommended configuration is as follows:
On the MWR 1900:interface Serial0/0:0no ip addressencapsulation pppkeepalive 1 2no cdp enableppp multilinkmultilink-group 1end
On the MGX-RPM-1FE-CP back card;interface Virtual-Template2bandwidth 1536no ip addresskeepalive 1 2no peer default ip addressppp multilinkmultilink-group 101end.
Note In the MGX-RPM-1FE-CP backcard configuration example, only the keepalive interface command and configuration recommendation is specific to implementation in an IP RAN solution.
This new feature is identified by CSCdy78207.
New Features in Cisco IOS Release 12.2(8)MC2c
The following new features are introduced in Cisco IOS Release 12.2(8)MC2c:
16 Multilink Interfaces Support
The MGX-RPM-1FE-CP now supports up to 16 multilink interfaces.
The additional interface support requires that the number of RTP compression-connections for an interface be managed using the ip rtp compression-connections command.
Up to 6000 compression-connections can be allocated with up to 1000 RTP compression-connections per multilink interface. If more than 6000 compression-connections are configured, an error message similar to the following will display whenever an interface comes up and it does not receive all of its requested compression-connections:
00:22:32:%IXP1200_CP-1-HPRX_CTX_MEM_POOL:Out of resources for Multilink5. Requested 1000 compression-connections, Obtained 900.
While an interface that does not obtain enough compression-connections will still function, the compression will be limited to the number of connections that it did obtain. If no compression-connections were obtained, all packets will be sent decompressed.
To view the number of RTP compression-connections configured for an interface, issue the show ip rtp header-compression command. In the following example, the interface has requested 1000 compression-connections, but only obtained 900. The interface still supports 1000 compression-connections for decompression but only 900 compression-connections for compression.Router2#show ip rtp header-compression multilink5RTP/UDP/IP header compression statistics:Interface Multilink5:Rcvd: 1286911 total, 1272389 compressed, 0 errors, 0 status msgs0 dropped, 0 buffer copies, 0 buffer failuresSent: 1288070 total, 1288040 compressed, 0 status msgs29624890 bytes saved, 24474050 bytes sent2.21 efficiency improvement factorConnect:1000 rx slots, 900 tx slots,1288070 long searches, 30 misses 0 collisions, 0 negative cache hits99% hit ratio, five minute miss rate 0 misses/sec, 0 max
This new features is identified by CSCdz00565.
ACFC and PFC Support on PPP Interfaces
By default, Address and Control Field Compression (ACFC) and Protocol Field Compression (PFC) are enabled on PPP interfaces. Both features are always enabled and will be negotiated on all serial interfaces.
Note If upgrading for this support, ensure that you upgrade the MGX-RPM-1FE-CP backcard images first. After doing so, immediately upgrade all MWR 1900 routers connected to the MGX-RPM-1FE-CP back card.
This new feature is identified by CSCdz15371.
Ignore IP ID Field Delta in cUDP Packet Flows Support
By default, the ability to ignore IP ID field delta in cUDP traffic flows is enabled. This ability eliminates the need to send information about the IP header ID field in compressed packets. The decompressor saves the original ID field from the full header packet and generates an ID field by incrementing it by one for each decompressed packet.
This feature improves processing efficiency; helping to minimize dropped packets and link saturation.
This feature is identified by CSCdy87595.
New in Cisco IOS Release 12.2(8)MC2d
The following new feature is introduced in Cisco IOS Release 12.2(8)MC2d.
Double cUDP Full Headers
At the start of a call flow, the MWR 1900 router and MGX 8850 RPM-PR back card now send the first two packets in the flow with full headers. This feature helps to minimize the loss of cUDP headers (and therefore misrouted packets) in noisy and/or congested networks.
This feature is identified by CSCdz84029.
Limitations, Restrictions, and Important Notes
When working with a MGX-RPM-1FE-CP back card, please take note of the following limitations, restrictions, and important notes:
•Only one MGX-RPM-1FE-CP back card is supported per Cisco MGX 8850 RPM-PR.
•FE and multilink interfaces should be shut down before online insertion and removal (OIR) of the MGX-RPM-1FE-CP.
•The MGX-RPM-1FE-CP is only supported on the Cisco MGX 8850 RPM-PR.
•For PPP Multiplexing, MLP must be configured on the MGX-RPM-1FE-CP back card.
•For error messages to be stored, console logging must be configured.
•The IP MTU should be set to 512 bytes or less on multilink interfaces.
•The MGX-RPM-1FE-CP back card supports up to 16 multilink interfaces.
•MLP with LFI is not supported by the Cisco MWR 1900 router. Therefore, MLP with LFI must be disabled on peer devices connecting to the Cisco MWR 1900 router T1 MLP connections.
•To fully disable PPP Multiplexing, issue the no ppp mux command on the T1 interfaces of the routers at both ends of the T1 link. If PPP Multiplexing remains configured on one side of the link, that side will offer to receive PPP multiplexed packets.
•If upgrading to Cisco IOS Release 12.2(8)MC2c or later for the ACFC and PFC support on PPP interfaces, ensure that you upgrade the MGX-RPM-1FE-CP backcard image first. After doing so, immediately upgrade all MWR 1900 routers connected to the MGX-RPM-1FE-CP back card.
Caveats in Cisco IOS Release 12.2(8)MC2d
The following sections list and describe the open and resolved caveats for the Cisco MGX-RPM-1FE-CP with Cisco IOS Release 12.2(8)MC2d. Only severity 1 through 3 caveats are included.
Caveats describe unexpected behavior in Cisco IOS software releases. Severity 1 caveats are the most serious caveats, severity 2 caveats are less serious, and severity 3 caveats are the least serious of these three severity levels.
Caveats in Cisco IOS Releases 12.2 and 12.2 T are also in Cisco IOS Release 12.2(8)MC2d. For information on caveats in Cisco IOS Release 12.2, see Caveats for Cisco IOS Release 12.2. For information on caveats in Cisco IOS Release 12.2 T, see Caveats for Cisco IOS Release 12.2 T. These two documents list severity 1 and 2 caveats and are located on CCO and the Documentation CD-ROM.
Note If you have an account with Cisco.com, you can use Bug Navigator II to find caveats of any severity for any release. To reach Bug Navigator II, Login to Cisco.com and click Software Center: Cisco IOS Software: Cisco Bugtool Navigator II. Another option is to go directly to http://www.cisco.com/support/bugtools.
This section lists the caveats that are open in Release 12.2(8)MC2d
Entering the no shut command on an RPM FE interface when the system is under a moderate to heavy load causes the CPU to spike to about 95% utilization for approximately 5 seconds. During this time, multilink interfaces and OSPF adjacencies flap, resulting in lost calls.
Workaround: Avoid issuing the no shut command on an RPM FE interface when the system is under a moderate to heavy load.
In an RPM-to-RPM multilink bundle with a single active member link on which cRTP is configured, periods of heavy compressed traffic with continuously changing flows might cause UDP checksum errors to occur on some decompressed packets
Workaround: Do not overdrive an RPM-to-RPM multilink bundle configured for RTP header compression.
This section lists the caveats resolved in Release 12.2(8)MC2d.
Noise, link overdrive, and other conditions might cause UDP packets to be lost or misrouted.
For more information about this resolved caveat, see the "Double cUDP Full Headers" section.
If the no ip rtp header-compression command is issued on an interface of a multilink bundle on which the total available number of compression connections (6000) has been allocated, the MGX-RPM-1FE-CP back card reloads.
During heavy traffic, UDP checksum errors might occur on packets decompressed by the MGX-RPM-1FE-CP back card after they have traversed a multilink bundle with a single active member link on which RTP header compression (cRTP) is configured.
To collect data for reporting back card and router issues, issue the following command:
•show tech-support—Displays general information about the router when it reports a problem.
•show logging—Displays information in the syslog history table.
This section contains information that was not included or was documented incorrectly in the MGX-RPM-1FE-CP Back Card Installation and Configuration Note. The heading in this section corresponds with the applicable section title in the documentation.
Configuring RTP/UDP Compression
The maximum number of RTP header compression connections is documented as 150 per T1 interface and up to 600 connections per MLP bundle when in fact, 1000 connections are supported per MLP bundle regardless of whether the bundle contains one T1 interface or four.
The show ppp mux Command
The efficiency improvement factor calculation documented in the show ppp mux command section is incorrect. The correct improvement factor calculation uses bytes, not packets, and is as follows:
Multiplex efficiency improvement factor = 100 * (Total bytes saved) / (Total bytes received)
Where total bytes saved = bytes_received_at_muxer - bytes_sent_at_muxer.
Demultiplex efficiency improvement factor = 100 * (Total bytes saved) / (Total bytes sent)
Where total bytes saved = bytes_sent_at_demuxer - bytes_received_at_demuxer.
The show ip rtp header-compression Command
The detail keyword is not supported in the show ip rtp header-compression command on the MGX-RPM-1FE-CP back card. Output does not display for the detail keyword if specified in command.
The following sections describe the available documentation related to the Cisco MGX-RPM-1FE-CP back card.These documents consist of hardware and software installation guides, Cisco IOS configuration guides and command references, system error messages, and other documents.
Documentation is available in printed or electronic form.
These documents are available for the Cisco MWR 1900 Mobile Wireless Edge Router on Cisco.com and the Documentation CD-ROM:
•MGX-RPM-1FE-CP Back Card Installation and Configuration Note
•RPM-PR Installation and Configuration
•Cisco MWR 1900 Mobile Wireless Edge Router
–Cisco MWR 1900 Hardware Installation Guide
–Cisco MWR 1900 Software Configuration Guide
–Cisco MWR 1900 Rack Mounting Instructions
–Cisco MWR 1900 Regulatory Compliance and Safety Information
•VWIC-2MFT-T1-DIR, VWIC-2MFT-E1-DIR Installation Instructions
Feature modules describe new features supported by Cisco IOS Release 12.2 MC and are updates to the Cisco IOS documentation set. A feature module consists of an overview of the feature, configuration tasks, and a command reference.
On Cisco.com at:
Technical Documents: Cisco IOS Software: Cisco IOS Release 12.2: New Feature Documentation: New Features in 12.2-Based Limited Lifetime Releases: New Features in Release 12.2 MC: New Features in Release 12.2 MC2
On the Documentation CD-ROM at:
Cisco Product Documentation: Cisco IOS Software Configuration: Cisco IOS Release 12.2: New Feature Documentation: New Features in 12.2-Based Limited Lifetime Releases: New Features in Release 12.2 MC: New Features in Release 12.2 MC2
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