Table of Contents

15-2-4GC3

Release Notes for Cisco IOS Release 15.2(4)GC3

Current Release:

15.2(4)GC3—November 2014

Previous Release:

15.2(4)GC2—July 2014

These releases support the Cisco 5900 Embedded Services Routers (ESR) and select ISR G2 platforms. These release notes are updated to describe new features, limitations, troubleshooting, recommended configurations, caveats, and how to obtain support and documentation.

Contents

This publication consists of the following sections:

- Image Information and Supported Platforms

- Related Documentation

- Limitations

- Recommended Configuration Settings

- Caveats

- Obtaining Documentation and Submitting a Service Request

Image Information and Supported Platforms

These images are bug compatible with Cisco IOS Release 15.2(4)M6.

Note You must have a Cisco.com account to download the software.

Cisco IOS Release 15.2(4)GC3 includes the following Cisco IOS image:

- c2900-universalk9-mz.SPA

- c2951-universalk9-mz.SPA

- c3900-universalk9-mz.SPA

- c3900e-universalk9-mz.SPA

- c5915-adventerprisek9-mz.SPA

- c5915-entbase-mz.SPA

- c5921i86-universalk9-ms.SPA

- c5930-adventerprisek9-mz.SPA

- c5940-adventerprisek9-mz.SPA

Cisco IOS Release 15.2(4)GC3 is supported on the following platforms:

- Cisco 2901 Integrated Services Router

- Cisco 2911 Integrated Services Router

- Cisco 2921 Integrated Services Router

- Cisco 2951 Integrated Services Router

- Cisco 3925 Integrated Services Router

- Cisco 3925e Integrated Services Router

- Cisco 3945 Integrated Services Router

- Cisco 3945e Integrated Services Router

- Cisco 5915 Embedded Services Router

- Cisco 5921 Embedded Services Router

- Cisco 5930 Embedded Services Router

- Cisco 5940 Embedded Services Router

Related Documentation

The following documentation is available:

- Software Configuration Guide for the Cisco 5900 Embedded Services Routers

http://www.cisco.com/c/en/us/td/docs/solutions/GGSG-Engineering/15-4-3M/config-guide/Configuration-Guide.html

- IOS Bulletins—You can find bulletins at:

http://www.cisco.com/c/en/us/products/ios-nx-os-software/ios-software-releases-listing.html

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 15.2(4)GC2 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 5921 ESR has the following limitations:

- With the 5921 ESR, if the user wishes to configure dot1q trunking, it is suggested that the Linux MTU be set to 1508. This is due to the fact that a frame of length 1500 (maximum, by default) is going to leave the 5921 application with a length of 1504 bytes (if using dot1q and for non-native VLAN) or of 1508 bytes (if using q-in-q and for non-native VLAN). Normally, Linux would either drop or fragment these frames. Configuring the MTU to 1508 in Linux will prevent the fragmentation or dropping of frames in the event that dot1q or q-in-q is configured on the 5921. Even if the Linux MTU is set to greater than 1500, the 5921 is going to "cap" its MTU at 1500 (to the 5921 application). This will mimic the behavior of a typical Cisco device.

- With the 5921 ESR, several situations have been encountered in which the e1000e Ethernet driver strips VLAN tags before a frame reaches the 5921. This will result in dot1q trunking not performing properly (the 5921 will receive frames with no VLAN tag, even though it is configured to expect VLAN tags). In IOS, you will notice this by seeing ARP or ping failures.

If you see such behavior, please issue the following debug command from IOS:

# debug arp

Now, try the ping again. If the VLAN tag stripping issue is present, you will see a "wrong cable" message similar to the following:

*Jan 14 21:49:50.874: IP ARP rep filtered src 192.168.110.2 e05f.b986.5500, dst 192.168.110.1 0022.4d7b.e424 wrong cable, interface Ethernet0/0.130

Now switch to the Linux command line and see if the e1000e driver is being used by issuing the following command (using eth0 as an example):

[root@router ~]# ethtool -i eth0

driver: e1000e <== LOOK FOR THIS

version: 2.3.2-k

firmware-version: 2.1-2

bus-info: 0000:02:00.0

supports-statistics: yes

supports-test: yes

supports-eeprom-access: yes

supports-register-dump: yes

supports-priv-flags: no

From the Linux command line, verify the VLAN mode of the device:

[root@router ~]# ethtool -d eth0

MAC Registers

-------------

0x00000: CTRL (Device control register) 0x58100248

Endian mode (buffers): little

Link reset: reset

Set link up: 1

Invert Loss-Of-Signal: no

Receive flow control: enabled

Transmit flow control: enabled

VLAN mode: enabled <== LOOK FOR THIS

Auto speed detect: disabled

Speed select: 1000Mb/s

Force speed: no

Force duplex: no

If the VLAN mode is enabled, this indicates that the driver is stripping the VLAN tags.

To remedy this using CentOS, please upgrade to the latest e1000e driver by following these steps from the Linux command line:

#yum install kernel-devel gcc gcc-c++ make wget

#reboot

#mkdir /usr/local/src/e1000e

#cd /usr/local/src/e1000e

#wget http://downloadmirror.intel.com/15817/eng/e1000e-3.0.4.tar.gz

#tar zxf e1000e-3.0.4.tar.gz

#cd e1000e-3.0.4

#cd src

#make install

If the process ends with the following message, ignore it:

/bin/sh: man: command not found

#rmmod e1000e

#modprobe e1000e

From the Linux command line, verify that the new driver has been activated:

[root@centos src]# ethtool -i eth0

driver: e1000e

version: 3.0.4-NAPI <== LOOK FOR THIS

firmware-version: 2.1-2

bus-info: 0000:02:00.0

supports-statistics: yes

supports-test: yes

supports-eeprom-access: yes

supports-register-dump: yes

supports-priv-flags: no

--------------------

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 command to turn off creation of virtual-template subinterfaces:

no virtual-template subinterface

- 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:

class-map match-any chat

match dscp af11

class-map match-any voice

match dscp ef

policy-map mypolicy

class chat

bandwidth percent 40

class voice

bandwidth percent 40

interface virtual-template number

service-policy output mypolicy

- No additional configuration is supported on the policy-map.

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:

interface virtual-template number

no keepalive

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 = 100

The following is an example configuration for a VMI interface on the virtual template when running bypass mode:

interface vmi1

…

ipv6 ospf cost dynamic weight throughput 0

ipv6 ospf cost dynamic weight resources 29

ipv6 ospf cost dynamic weight latency 29

ipv6 ospf cost dynamic weight L2-factor 29

…

ospfv3 cost dynamic weight throughput 0

ospfv3 cost dynamic weight resources 29

ospfv3 cost dynamic weight latency 29

ospfv3 cost dynamic weight L2-factor 29

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.html

Use 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.

interface vmi number

no ip split-horizon eigrp as-number

- Enter the following command to disable the ip redirects on the vmi interface when you are configuring the vmi interface for EIGRP:

interface vmi number

no ip redirects

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:

metric weights tos k1 k2 k3 k4 k5

where tos denotes type of service (currently, it must always be zero) and use the following default values for weights:

k1 - 1

k2 - 0

k3 - 1

k4 - 0

k5 - 0

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:

– Change Based Dampening:

ip50-1(config)#int vmi 4

ip50-1(config-if)#eigrp 100 interface dampening-change 40

Default Value for Change Based Dampening:

50%

To enable change-based dampening using the default Value, enter the following command:

eigrp 100 interface dampening-change

To disable change-based dampening, enter the following command:

no eigrp 100 interface dampening-change

– Interval-based Dampening:

ip50-1(config)#int vmi 4

ip50-1(config-if)#eigrp 100 interface dampening-interval 20

Default Timer value for Interval-based Dampening:

30 seconds

To enable interval-based dampening using the default Value, enter the following command:

eigrp 100 interface dampening-interval

To disable interval-based dampening, enter the following command:

no eigrp 100 interface dampening-interval

- The following exceptions will result in an immediate update:

– a down interface

– a down route

– 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:

- Enter the following command to turn Waas Express on the Wan interface:

waas enable

- Enter the following commands to enable full optimizations:

parameter-map type waas waas_global

tfo optimize full

- Enter the following commands to enable application accelerators:

parameter-map type waas waas_global

accelerator http-express

enable

accelerator cifs-express

enable

accelerator ssl-express

enable

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).

Cisco IOS Release 15.2(4)GC3

The following sections list caveats for Cisco IOS Release 15.2(4)GC3:

Closed Caveats

- CSCur15562

On the c5940, when registering a hardware SEC Engine as a valid hardware entropy source, the crypto packets would be depleted after 256 attempts of entropy collection (roughly 10 days).

- CSCup61110

Previously, when the c5940 did not have a start up config(i.e after a write erase), it would display some messages during boot up that were not informative.

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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