Embedded Services Routers Release Notes for Cisco IOS Release 15.4(2)T
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Release Notes for Cisco IOS Release 15.4(2)T
Image Information and Supported Platforms
Recommended Configuration Settings
Obtaining Documentation and Submitting a Service Request
Release Notes for Cisco IOS Release 15.4(2)T
The following release notes support Cisco IOS Releases 15.4(2)T and higher releases. These releases support the Cisco 5900 Embedded Services Routers (ESR) platforms. These release notes are updated to describe new features, limitations, troubleshooting, recommended configurations, caveats, and how to obtain support and documentation.
Image Information and Supported Platforms
Note You must have a Cisco.com account to download the software.
Cisco IOS Release 15.4(2)T includes the following Cisco IOS images:
Limitations
This release has the following limitations:
- The Quality of Service (QoS) policy can only be applied to one outgoing interface the Point-to-Point Protocol over Ethernet (PPPoE) session is traversing.
A QoS output policy can be applied to the Virtual Template or the Virtual Multipoint Interface (VMI), but not at the same time. If a policy is attached, the outgoing physical interfaces (i.e., physical-interface FastEthernet0/0) should not have output policy applied. It is recommended that the policy be attached to the Virtual Template. The other option is to apply the policy to the VMI, but not to the Virtual Template or Ethernet interface.
- When a service policy is applied to the VMI and packets are dropped on the VA due to credit starvation, the show policy-map int VMI command will not show these dropped packets. There is no back pressure between the interfaces in this configuration. The VMI does not know that packets were dropped by the Virtual Access (VA) or the Ethernet physical interfaces.
- RFC 5578 credits do not tie into QoS formulas. Credits only indicate to QoS the ability to transmit a packet or not. If there are enough credits a packet will be transmitted from the highest priority queue. When there are not enough credits, packets will be queued.
- QoS policy may drop on an interface when the interface receives an invalid CDR value.
- To prevent dropping QoS policy, the current data rate (CDR) is range checked to a floor value of 10kbps and a ceiling value of the physical interface speed. If CDR is below the floor value, the QoS rate shaping is set to the floor value. If CDR is above the ceiling value, the QoS rate shaping is set to the ceiling value. The floor value is 10kbps. The ceiling value is limited to the physical interface speed.
- Software Release 15.X may have OSPFv3 incompatibility issues while in Mobile Ad Hoc Networks (MANET) mode with software versions 12.4(24)GC or previous versions. To avoid any issues, ensure that all routers run the same version of Cisco IOS.
- CSCtx62099
If the size of the IP mux MTU is larger than the MTU of the outbound interface, a superframe may not be transmitted, or it might fragmented properly but not re-assembled at the receive side. A format error occurs on the demux interface. This is only an IPv4 issue; IPv6 does not support router packet fragmentation.
Workaround : Reduce the MTU size in the profile to the size of the interface MTU.
The Cisco 5915 ESR has the following limitations:
- The Virtual Local Area Network (VLAN) database is maintained in the flash as a file (vlan.dat). This file is created or updated only while adding, deleting, or modifying a VLAN to a switchport. Do not delete the vlan.dat file.
Copying a configuration, with switch ports configured with VLANs, through Trivial File Transfer Protocol (TFTP) to the Cisco 5915 ESR running configuration, the vlan.dat file may not be created automatically in flash. As a result, the VLANs configured in the switch ports do not exist, even though the running config shows the switch ports configured with VLANs. If a VLAN appears as 'Line protocol down' the VLAN association needs to be updated by configuring the VLAN database explicitly by entering the vlan vlan_number command.
When you copy any configuration file with VLAN configurations to TFTP server, back up the corresponding vlan.dat file to TFTP. And when you copy a configuration file from a TFTP server to the Cisco 5915 ESR, copy the corresponding vlan.dat file to C5915 router flash (CSCtq04969).
- When you copy files to the flash, the copy process may become very slow when flash has limited free space. Delete unused files to free up space. If the issue persists, enter the format flash command to reclaim space from the deleted files ( CSCtl42754).
- The Output drops counter may not be accurate under stress. You can verify the number of output drops in output for the show controller command (CSCtl70552).
Recommended Configuration Settings
Use the following configuration guidelines when enabling class-based weighted fair-queuing:
- Enter the following commands to create a policy map with class-based weighted fair-queuing and apply the newly created policy-map to the virtual template:
Use the following configuration guidelines when disabling Point to Point Protocol (PPP) keepalives:
- You can turn off the PPP keepalive messages to decrease overhead when the radio alerts the router with a PPPoE Active Discovery Terminate (PADT) message that the layer-2 RF connection is no longer available. Turning off the PPP keepalive messages may also avoid the potential for the router to terminate the connection based on missed PPP keepalives over a poor radio frequency (RF) link.
- To turn off the PPP keepalive messages, enter the following command for the virtual-template:
Use the following configuration guidelines for setting the recommended Open Shortest Path First (OSPF) values of radio link metrics:
- You may have to dampen the amount of changes in order to reduce network-wide churn because cost components may change rapidly.
- The following recommended values are intended as a starting point for optimizing an OSPFv3 network and are based on network simulations that may reduce the rate of network changes. Each network may have unique characteristics that require different settings to optimize actual network performance.
You must configure these values for both OSPFv3 IPv4 and IPv6:
S1 = ipv6 ospf dynamic weight throughout
Recommended value = 0
Default=100
S2 = ipv6 ospf dynamic weight resources
Recommended value = 29
Default = 100
S3 = ipv6 ospf dynamic weight latency
Recommended value = 29
Default = 100
S4 = ipv6 ospf dynamic weight L2 factor
Recommended value = 29
Default = 100The following is an example configuration for a VMI interface on the virtual template when running bypass mode:
For more information on OSPF commands, refer to the following URL:
http://www.cisco.com/en/US/docs/ios/iproute_ospf/command/reference/iro_book.htmlUse the following configuration guidelines for disabling split horizon in EIGRP:
- By default split horizon is enabled in EIGRP. You can disable split horizon by entering the no ip split-horizon eigrp command for the respective autonomous system number.
- Enter the following command to disable the ip redirects on the vmi interface when you are configuring the vmi interface for EIGRP:
Use the following configuration guidelines for setting EIGRP values of radio link metrics:
- EIGRP monitors the following metrics on an interface allowing the tuning of the EIGRP metric calculations; use the metric weights router configuration command:
where tos denotes type of service (currently, it must always be zero) and use the following default values for weights:
Note The no metric weights command restores the K-values to the defaults listed above.
- Most configurations use the Delay and Bandwidth metrics with Bandwidth taking precedence.
- You must set the weights identically on all routers in an autonomous system.
Note If you wish to use the default K-values you do not need to enter the metric weights command.
- To set the metric dampening value for EIGRP, enter the following commands for either change-based or interval-based dampening of metric updates received through VMI:
Default Value for Change Based Dampening:
50%To enable change-based dampening using the default Value, enter the following command:
To disable change-based dampening, enter the following command:
Default Timer value for Interval-based Dampening:
30 secondsTo enable interval-based dampening using the default Value, enter the following command:
To disable interval-based dampening, enter the following command:
–
any change in a metric triggered outside the scope of the VMI metric update
Note No recommended values other than default are currently available.
For more information on EIGRP commands, refer to:
http://www.cisco.com/en/US/docs/ios/iproute_eigrp/command/reference/ire_book.html
Use the following configuration guidelines to enable Waas Express:
For more information on Waas Express configuration, refer to the following URLs:
http://www.cisco.com/en/US/docs/ios/wan/configuration/guide/cfg_waas_exp.pdf
http://www.cisco.com/en/US/docs/ios-xml/ios/wan_waas/configuration/15-2mt/wan-cfg-waas-exp.html
Caveats
Caveats describe unexpected behavior in Cisco IOS releases. Caveats listed as open in a prior release are carried forward to the next release as either open or closed (resolved).
Open Caveats
For the 5915 ESR configured with 'ip mobile router-service', when an ethernet cable is unplugged from the FA 0/0 interface the router crashes.
Workaround : Use the shutdown command to shutdown the port before unplugging the cable.
For the 5921 ESR, when 802.1Q is configured on the IOS interface but is not configured on the Linux interface, max MTU outbound packets will be dropped.
Workaround: Increase the linux mtu by 4 bytes to 1504 instead of 1500. This will allow the 5921 to send full MTU sized packet of 1500 in IOS without Fragmentation.
For the 5921 ESR a condition exists where several subinterfaces are created on a physical port and you cannot ping or arp across a dot1q interface.
When the console of the 5921 is active, and the 5921 is under an active packet forwarding load, there is an increase in the CPU usage consumed by the IOS process. This condition is seen using the Linux process monitoring tool, top.
Workaround : Do not start the swrvcon process unless you need to use the console.
For the 5921 ESR, in certain instances performing a "shutdown" on an interface can result in excessively high CPU utilization. The CPU utilization can be determined by using the Linux application, "top".
Workaround : Either leave the interface in a "no shutdown" state, or unplug the cable.
EIGRP Update packets are getting dropped over a VMI interface between the C5921 IOS and the Linux interface when a DLEP session is established between peers.
With NAT enabled on a VRF, you may experience a crash and reload when making changes to an interface IP address.
Condition : This has only been seen when NAT is enabled on a VRF.
A video call on any ESR platform between SIP phones comes up without video channel. If the receiving phone puts the phone on hold and resumes the call, the video displays.
Workaround: Configure asymmetric payload support for dynamic codecs on the voice service:
(conf-voi-serv)# asymmetric payload dynamic-codecs
A router configured to NAT an encrypted (IPsec) GRE tunnel source doesn't actually do the NAT-ing unless CEF is disabled.
Workaround : Disable IP CEF switching ('no ip route-cache cef') on the physical interface, where the data packets arrive that are being forwarded out through the tunnel.
Closed Caveats
On the 5921 ESR, during the launch of the image, a segmentation fault can occur when the Voip Null0 interface goes down.
When an ACL is placed on an inbound interface, and IP multiplexing is enabled on the interface, traffic that was "not filtered" was received after being de-muxed by IP multiplexing.
When PPPoE is configured on radio interfaces between two routers, and a shut and no shut are issued on the remote interface of router2, packets are stuck in the Router1 input queue.
The WAAS-Express router crashes when HTTP-Express Accelerator is enabled and HTTP traffic is going through the WAAS-Express router. This condition is only seen if the response header is split across multiple receives on WAASX.
Obtaining Documentation and Submitting a Service Request
For information on obtaining documentation, using the Cisco Bug Search Tool (BST), submitting a service request, and gathering additional information, see What’s New in Cisco Product Documentation at: http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html.
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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