Cisco UCM CAR (CDR) Web GUI Access Request (https:///car/)


To provide a user to CAR (CDR)  (https://<CAR server IP Address>/car/) web page, the following two access groups must be associated with the user. After giving user this access, please test login to other areas of UCM GUI, so the users do not gain unapproved access to UCM Admin pages.


  1. Standard CCM End Users
  2. Standard Admin Rep Tool Admin = (Standard CAR Admin Users, Standard CCM Super Users)


CAR web gui


Interview question: Cisco Voice Engineer: CUCM Database replication value, do you know what you are talking about?

This is a helpful reminder note for all who manages CUCM on day-to-day basis and one of the favorite Voice/IPTel Engineer interview questions. I think I was asked this question in almost every voice Engineer role interviews. Good luck with your next interview!

Q1. What does CUCM database replication value mean to you (CM Administrator)? 

2 = Good, excellent, no behind pain

Other than 2 = Behind pain begins

Value Meaning Description
0 Initialization State This state indicates that replication is in the process of trying to  setup. Being in this state for a period longer than an hour could  indicate a failure in setup.
1 Number of Replicates not correct This state is rarely seen in 6.x and 7.x but in 5.x can indicate its  still in the setup process. Being in this state for a period longer than  an hour could indicate a failure in setup.
2 Replication is good Logical connections have been established and tables match the other servers on the cluster.
3 Tables are suspect Logical connections have been established but we are unsure if tables match.
In 6.x and 7.x all servers could show state 3 if one server is down in  the cluster.
This can happen because the other servers are unsure if  there is an update to a user facing feature that has not been passed  from that sub to the other device in the cluster.
4 Setup Failed / Dropped The server no longer has an active logical connection to receive  database table across. No replication is occurring in this state.

Source: CCO

Q2. How to check?

Option 1: On CUCM OS CLI, run show command

admin:show perf query class “Number of Replicates Created and State of Replication”
==>query class :

– Perf class (Number of Replicates Created and State of Replication) has instances and values:
ReplicateCount -> Number of Replicates Created = 427
ReplicateCount -> Replicate_State = 2 <<< Life is Good

Option 2: On CUCM Unified Reporting 

Cisco Unified Reporting > System Reports > Unified CM Database Status >> Run report



Option 3: Real Time Monitoring Tool (RTMT)

Install RTMT plugin on your desktop. Launch RTMT and then go to “Call Manager > Service > Database Summary”

Q3. How to repair a broken db replication issue?

I have come acorss a very good blog and it shows you on how to repair a broken db replication. Click here.




Notes on Cisco QoS: Clearing the fog – Part 2. Quality issues

Quality of Service

QOS = Method of giving priority to some specific traffic as moving over the network.

The basic aim of QoS is to have a consistent and predictable performance on your network.


1 qos intro

General characteristics of today’s Converged Network:

  • Small voice packet compete with bursty data packets, many different applications are using network as services
  • Critical traffic must get priority over less critical traffic, without QoS, default behavior is First In First Out (FIFO)
  • Voice and video traffics are time-sensitive
  • Outages are not acceptable


Converged Network Quality issues:

  • Lack of Bandwidth
  • Packet Loss
  • Delay
  • Jitter



2 Bandwidth Measure.png

  • Maximum available bandwidth is the slowest link on the traffic paths
  • On the same physical links (traffic paths), multiple flows compete for the same bandwidth, multiple applications sharing the same bandwidth
  • Lack of bandwidth causes performance degradation on network applications



Packet Loss

3 Tail Drop due to Queue Congestion

Packet loss due to Tail Drop: Queue only can so much packets and once it is full and more packets arrive at the tail end of the queue before the queue is emptied (due to link congestion etc.), the packets will be dropped, and this behavior is called ‘Tail Drop’. If the tail drop occurs to the time sensitive traffics such as voice and video, the effects are immediately felt by the users on the flow. If this happens to data traffic, it may interrupt file transfer and corrupt the file.




4 Types of Delay

  • Processing Delay – time taken by router to process packets from an input interface and put them into the output queue of output interface
  • Queuing Delay – time a packet resides in the output queue of a router
  • Serialization Delay – time taken to place bits on the wire
  • Propagation Delay – time taken for packets to cross links from one end to the other end




5 Jitter

  • Packets from a source will reach a destination with different delay times
  • Congestion on the network will cause jitter
  • Congestion can occur at a router interface/Service Provider network if the circuits are not properly provisioned


CUBE High Availability (HA) Using HSRP Configuration with port-channel twist

Starting with Cisco Gen2 router platforms, CUBE can provide the HSRP (Hot Standby Routing Protocol). That is you need two CUBE routers to confgure this setup. HSRP basically works on Active and Standby mode between two routers by monitoring both the inside and outside interfaces, if Active side goes down, then the Standby device becomes active and takes over the responsibilities of the Active router.

In CUBE HSRP Active/Standby pair scenario, the two CUBE routers keep exchange communications over the same virtual IP address. This setup will support media preservation over an HSRP switchover of SIP to SIP calls, but not the call signaling. Call signaling preservation is supported from IOS 15.2.3T.

1. Two identical ISR G2 routers with the correct IOS and license
*Cisco 2951 (x 2), IOS = c2951-universalk9-mz.SPA.154-3.M1, license =SL-29-UC-K9
2. Identiacal CUBE configuration
3. SIP-to-SIP call flows
1. Enable CUBE and CUBE Redundancy

Enable CUBE on CUBE01 and CUBE02:
voice service voip
mode border-element
allow-connections sip to sip

Enable CUBE redundancy and call checkpointing on both CUBES
voice service voip
2. Enable HSRP

Enable router redundancy schemes on both routers, where:
scheme – redundancy state tracking scheme
standby – enable standby (HSRP) state tracking scheme
SB – the HSRP standby group name

redundancy inter-device
scheme standby SB

3. Configure HSRP Communication Transport

Configure the HSRP Inter-Device Communication Transport as follows:

Active Configuration:
ipc zone default <<< For Inter-Device Communication Protocol (IPC)
association 1 <<< Associates between two devices
no shutdown <<< Enables associations
protocol sctp <<< Stream Control Transmission Protocol (SCTP) for communication language
local-port 5000 <<< Defines the local SCTP port number
local-ip <<< Defines the local router’s IP address
remote-port 5000 <<< Defines the remote SCTP port number
remote-ip <<< Defines the remote router’s IP address

Standby Configuration:
ipc zone default
association 1
no shutdown
protocol sctp
local-port 5000
remote-port 5000

4. Configure HSRP on the Interfaces

Configure the HSRP Inter-Device Communication Transport as follows:

Active Configuration

interface Port-channel1
description CUBE01 interface
ip address
standby delay minimum 30 reload 60 <<< Avoids race condition to establish contact between Active and Standby
standby version 2
standby 0 ip
standby 0 priority 50
standby 0 preempt
standby 0 name SB

interface GigabitEthernet0/0
no ip address
duplex full
speed 1000
channel-group 1

interface GigabitEthernet0/1
no ip address
duplex full
speed 1000
channel-group 1
Standby Configuration:

interface Port-channel1
description CUBE02 interface
ip address
standby delay minimum 30 reload 60
standby version 2
standby 0 ip
standby 0 priority 50
standby 0 preempt
standby 0 name SB

interface GigabitEthernet0/0
no ip address
duplex full
speed 1000
channel-group 1

interface GigabitEthernet0/1
no ip address
duplex full
speed 1000
channel-group 1
5. Configure the HSRP Timers

CUBE01(config-if)#standby 0 timers 2 msec 40 <<< configures failover and hold timers

CUBE02(config-if)#standby 0 timers 2 msec 40
6. Configure the Media Inactivity Timer

Enables the Active/Standby router pair to monitor and disconnect calls if no Real-Time Protocol (RTP) packets are received within a configurable time period. Default value is 28 seconds.

ip rtcp report interval 3000
media-inactivity-criteria all
timer receive-rtp 86400
timer receive-rtcp 5
7. Configure SIP Binding to HSRP Address

voice service voip
mode border-element license capacity 125
allow-connections sip to sip
bind control source-interface Port-channel1
bind media source-interface Port-channel1
asserted-id pai
asymmetric payload full
midcall-signaling passthru
privacy-policy passthru
sip-profiles 100
8. Reload the Routers

Active Router
CUBE01#show redundancy inter-device
Redundancy inter-device state: RF_INTERDEV_STATE_ACT
Scheme: Standby
Groupname: b2bha Group State: Active
Security: Not configured

Standby Router
CUBE02#show redundancy inter-device
Redundancy inter-device state: RF_INTERDEV_STATE_STDBY
Scheme: Standby
Groupname: b2bha Group State: Standby
Security: Not configured
9. Point Attached Softswitches to the CUBE HSRP Virtual Address
On CUCM, this is configured on the SIP Trunk configuration under Device > Trunk.

SIP Trunk


Useful commands for verification and troubleshooting:
show redundancy inter-device
show redundancy states
show standby brief
show standby
show voice high-availability summary
show voice high-availability summary | include media
show voip rtp connection
show sip-ua status
show sip-ua statistics
debug standby

show process cpu history
show process cpu sorted


Notes on Cisco QoS: Clearing the fog – Part 1. Basic Introduction

  1. What is Quality of Service (QoS) ?

Analogy 1: QoS is a network tool which can be implemented to effectively transport more critical traffics over IP, which gives critical traffic a priority over less critical traffic.

Analogy 2: QoS is a method of giving a priority to some specific data traffic going across our network.

  • Give VoIP, Video traffic more priority than ftp file downloading traffic
  • Some critical Data such as Citrix etc.


  1. Converged Network Quality Issues

Today’s enterprise network Characteristics:

  • Benign small voice packet flows compete directly with busty data packet flows.
  • Voice load and voice application data (traffic) tolerate minimal variation in delay, packet loss or jitter. The voice quality degradation is immediately felt by the users.
  • Give critical traffic higher priority
  • Voice and video are real-time, hence time-sensitive
  • Outage/packet drops are not acceptable


Some issues from Converged Network:

  • Lack of bandwidth – If more traffic is pumped through the network more than the network can handle, there will be congestions and packet loss.
  • Packet Loss – If input queue pumps too much packets into an interface, output queue fills up, the packet is dropped.
  • Delay –
    • Processing delay – The time it takes for a router to take the packet from an input interface, examine it and put it into the output queue of the output interface
    • Queuing delay – The time a packet resides in the output queue of a router
    • Serialization delay – The time it takes to place the “bits on the wire”
    • Propagation delay – The time it takes for the packet to cross the link from one end to the other


  • Jitter –
    • Packets from the source will reach the destination with different delays
    • Jitter is generally caused by congestion in the IP network
    • The congestion can occur either at the router interfaces or in a provider or carrier network if the circuit has not been provisioned properly


To overcome these converged network quality issues, QoS tool(s) must be used based on each network.


Some Cisco recommended QoS tool types and their characteristics:

A. Best effort

– Out of box, if you do not configure your devices, it is using best effort

– Business network with no QoS policies

– Infrastructure does not support QoS



B. Integrated Services (IntServ)

– Aims to reserve bandwidth along a specific path in the network

– Guarantees end-to-end bandwidth for mission-critical applications such as VoIP and Citrix

– End-hosts signal their QoS requirements to the network (Signalled QoS model)

– Every communication stream needs to request resources from the network.

– Edge routers use Resource Reservation Protocol (RSVP) to signal and reserve bandwidth


Some disadvantages of IntServ:

– Every device along the network must be fully RSVP aware and have ability to process QoS

– Reservations in each devices along the path need to be periodically refreshed, adds traffic and overhead along the network

– “Soft-states” or bandwidth reservation increase memory and CPU requirements on devices along the path

– Adds complexity to the network which makes network infrastructure difficult to maintain


C. Differentiated Service (DiffServ)

– Designed to overcome the limitations of Best-Effort and IntServe model, while maintaining the ability to provide an almost guaranteed QoS

– Routers and switches are configured to service multiple classes of traffic with different priorities. Bandwidth, delay and prioritization are configured on a hop-to-hop basis along the network infrastructure, making diffServ cost-effective and scalable

– For DiffServ QoS to work, network traffic must be divided into classes that are based on the company’s requirements

– Network devices identify traffic as it passes through them and enforce the configured policies, making sure that each class/service is served as instructed