Multisite Deployment Challenge Overview ccsp coaching center in delhi gurgaon

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 In a multisite deployment, some of the challenges that can arise include the following:
• Quality issues: Real-time communications of voice and video must be prioritized over a
packet-switching network. All traffic is treated equally by default in routers and switches. Voice
and video are delay-sensitive packets that need to be given priority to avoid delay and jitter
(variable delay), which would result in decreased voice quality.
4 Chapter 1: Identifying Issues in a Multisite Deployment
• Bandwidth issues: Cisco Unified Communications (Cisco UC) can include voice and
video streams, signaling traffic, management traffic, and application traffic such as rich
media conferencing. The additional bandwidth that is required when deploying a Cisco
Unified Communications solution has to be calculated and provisioned for to ensure
that data applications and Cisco Unified Communications applications do not overload
the available bandwidth. Bandwidth reservations can be made to applications through
QoS deployment.
• Availability issues: When deploying Cisco Unified Communications Manager (CUCM)
with centralized call processing, IP Phones register with CUCM over the IP LAN and
potentially over the WAN. If gateways in remote sites are using Media Gateway
Control Protocol (MGCP) as a signaling protocol, they also depend on the availability
of CUCM acting as an MGCP call agent. It is important to implement fallback
solutions for IP Phones and gateways in scenarios in which the connection to the
CUCM servers is broken because of IP WAN failure. Fallback solutions also apply to
H.323 gateways but are already created with H.323 dial peers in a proper H.323
gateway configuration.
NOTE Cisco Unified Communications Manager (CUCM) used to be called Cisco
CallManager (CCM).
• Dial plan issues: Directory numbers (DN) can overlap across multiple sites. Overlapping
dial plans and nonconsecutive numbers can be solved by designing a robust multisite
dial plan. Avoid overlapping numbers across sites whenever possible for an easier
design.
• NAT and security issues: The use of private IP addresses within an enterprise IP
network is very common. Internet Telephony Service Providers (ITSP) require unique
public IP addresses to route IP Phone calls. The private IP addresses within the
enterprise have to be translated into public IP addresses. Public IP addresses make the
IP Phones visible from the Internet and therefore subject to attacks.
NOTE The challenge of NAT and security is not limited to multisite deployments. For
example, for Cisco Attendant Console (AC), the line-state and call-forwarding status of
the primary line of each user is presented with each record entry. When you use CUCM
and Attendant Console across Network Address Translation (NAT) interfaces, or when
a firewall is between them, TCP traffic works correctly with the NAT transversal. Therefore,
most of the AC functionality works. However, the problem is with the Attendant Console
line status, which uses User Datagram Protocol (UDP). Also, the UDP traffic from the
CUCM servers cannot pass through the NAT interfaces. Therefore, the needed UDP ports
must be opened through the firewall.