[cisco-voip] CCM Clustering IP Block

[Andrew Dignan]

It isn't really the "ip block" that matters.  As long as the the
requirements below are met(this is for CM 4.x):

Taken from SRND
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00802c37c8.html#wp1038953

WAN Considerations

•Every 10,000 busy hour call attempts (BHCA) between sites that are
clustered over the WAN requires 900 kbps of bandwidth for Intra-Cluster
Communication Signaling (ICCS). This is a minimum bandwidth requirement,
and bandwidth is allocated in multiples of 900 kbps. The ICCS traffic
types are classified as either priority or best-effort. Priority ICCS
traffic is marked with IP Precedence 3 (DSCP 26 or PHB AF31 in Cisco
CallManager releases prior to 4.0 and DSCP 24 or PHB CS3 for release 4.0
and later). Best-effort ICCS traffic is marked with IP Precedence 0 (DSCP
0 or PHB BE).

•The minimum recommended bandwidth between sites that are clustered over
the WAN is 1.544 Mbps. This amount allows for the minimum of 900 kbps for
ICCS and 644 kbps for SQL, LDAP, and other inter-server traffic.

For clustering over the WAN to be successful, you must carefully plan,
design, and implement various characteristics of the WAN itself. The
Intra-Cluster Communication Signaling (ICCS) between Cisco CallManager
servers consists of many traffic types. The ICCS traffic types are
classified as either priority or best-effort. Priority ICCS traffic is
marked with IP Precedence 3 (DSCP 26 or PHB AF31 in Cisco CallManager
releases prior to 4.0 and DSCP 24 or PHB CS3 for release 4.0 and later).
Best-effort ICCS traffic is marked with IP Precedence 0 (DSCP 0 or PHB
BE). The various types of ICCS traffic are described in Intra-Cluster
Communications, which also provides further guidelines for provisioning.
The following design guidelines apply to the indicated WAN
characteristics:

•Delay

The maximum one-way delay between any Cisco CallManager server for all
priority ICCS traffic should not exceed 20 ms, or 40 ms Round Trip Time
(RTT). Delay for other ICCS traffic should be kept reasonable to provide
timely database and directory access. Measuring the delay is covered in
Delay Testing. Propagation delay between two sites introduces 6
microseconds per kilometer without any other network delays being
considered. This equates to a theoretical maximum distance of
approximately 3000 km for 20 ms delay or approximately 1860 miles. These
distances are provided only as relative guidelines and in reality will be
shorter due to other delay incurred within the network.

•Jitter

Jitter is the varying delay that packets incur through the network due to
processing, queue, buffer, congestion, or path variation delay. Jitter for
the IP Precedence 3 ICCS traffic must be minimized using Quality of
Service (QoS) features.

•Packet loss and errors

The network should be engineered for zero percent packet loss and errors
for all ICCS, especially the priority ICCS traffic, because packet loss
and errors will have adverse effects on the real-time call processing
within the cluster.

•Bandwidth

Provision the correct amount of bandwidth between each server for the
expected call volume, type of devices, and number of devices. This
bandwidth is in addition to any other bandwidth for other applications
sharing the network, including voice and video traffic between the sites.
The bandwidth provisioned must have QoS enabled to provide the
prioritization and scheduling for the different classes of traffic. The
general rule of thumb for bandwidth is to over-provision and
under-subscribe.

•Quality of Service

The network infrastructure relies on QoS engineering to provide consistent
and predictable end-to-end levels of service for traffic. Neither QoS nor
bandwidth alone is the solution; rather, QoS-enabled bandwidth must be
engineered into the network infrastructure.



> Hi All,
>
> Has anybody tried adding a callmanager subscriber that is not within
> the existing cluster's IP block ? I was wondering if this would create
> problems
> to the clustered system.
>
> Thanks,
> Ryan
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