This section describes the bandwidth
requirements for 50, 250, 800 and 2000 user systems. Meeting the bandwidth
requirements outlined in the section will provide a quality end user experience
for your users who host and attend WebEx meetings, and helps ensure that your
network can support the traffic demands from the web sharing, audio, and video.
Estimating
Bandwidth for End User Sessions
It is important to estimate the
network bandwidth to support the traffic demands of video, audio, and web
sharing for the size of your user system. The bandwidth requirements for this
product are fundamentally the same as for Cisco WebEx cloud services. If you
wish to optimize your network provisioning, Cisco WebEx cloud services
bandwidth usage is presented in the
WebEx Network Bandwidth
White Paper.
The information in
the following table shows the expected bandwidth for video, audio and web
sharing.
WebEx
Meeting Component
|
Aggregate End User Session Bandwidth
|
Video
(360p + 6 thumbnails)
|
1.5 Mb/s
|
Audio
|
0.1 Mb/s
|
Web
sharing
(This
value assumes you flip a slide every 30 seconds.)
|
0.6 Mb/s
|
Total maximum bandwidth
|
2.2 Mb/s
|
Although 2.2 Mb/s
is the maximum expected bandwidth for a single user connection, Cisco
recommends using the maximum expected bandwidth of 1.5 Mb/s when calculating
bandwidth requirements. Because only one-half of the maximum number of users
can employ video, audio, and web sharing while the remaining users should use
only audio and web sharing, this yields an average bandwidth of approximately
1.5 Mb/s per user connection.
If you refer to
the
WebEx Network
Bandwidth White Paper, you will notice that the bandwidth values in the
preceding table are based on worst-case traffic conditions. Average bandwidth
utilization is
much
smaller, but Cisco recommends using worst case numbers for the following
reasons:
-
Using the
worst case numbers for your calculation should help you provide the needed
bandwidth to prevent a degraded user experience as a result of heavy usage.
-
The Cisco
WebEx Meetings Server sends the same data simultaneously to all the
participants in a meeting. When a WebEx host flips a page on a presentation, an
image of that page (possibly comprising several megabytes) is sent separately
to each endpoint, simultaneously, and as quickly as possible.
Bandwidth on
Network Paths
Use the following
process to determine the necessary bandwidth on various network paths.
- Determine the averaged
bandwidth for a user session using the table provided in the preceding section.
-
Determine the
maximum number of users you expect to connect simultaneously over that link.
-
Multiply the
total bandwidth by the maximum number of users.
Scenario
examples:
-
If you expect
a maximum of 100 users to connect concurrently from the Internet, you will
probably need 1.5 Mb/s x 100 = 150 Mb/s of available bandwidth on your ISP
connection and through your external firewall to the Internet Reverse Proxy.
For mor details about Internet Reverse Proxy, see
Network Considerations for the Internet Reverse Proxy
-
Assume you
have a 2000 user system with all connections going through the Internet Reverse
Proxy. In this scenario, you need to assume traffic for all 2000 users will
connect to the Internet Reverse Proxy, and then from the Internet Reverse Proxy
to the internal virtual machines. The aggregate bandwidth coming into the
Internet Reverse Proxy from other parts of the network will be 2000 x 1.5 Mb/s
= 3 Gb/s. For more details about non-split-horizon, see
Non-Split-Horizon Network Topology.
Note |
The same 3
Gb/s of traffic passes inbound and outbound through the Internet Reverse Proxy,
requiring the NIC on the Internet Reverse Proxy to handle 6 Gb/s of user
traffic. See the next section for more information about bandwidth requirements
for the NIC on the Internet Reverse Proxy.
|
-
Assume you
have 2000 user system in a split-horizon DNS deployment. In this scenario, your
Internet users will connect to the Internet Reverse Proxy while intranet users
connect directly to the internal virtual machines. Assume ten percent of your
users connect to a meeting using the Internet versus 90 percent of users
connect to their meetings through the Intranet. The result is the aggregate
bandwidth coming into the Internet Reverse Proxy will now be approximately 300
Mb/s (10 percent of 2000 users times 1.5 Mb/s equals 300 Mb/s). If that same
300 Mb/s of traffic passes from the Internet Reverse Proxy, the NIC on the
Internet Reverse Proxy may be required to handle 600 Mb/s of user traffic. This
is a dramatically lower bandwidth requirement than with a non-split-horizon DNS
deployment described in the previous scenario. The reduction in network traffic
has direct bearing on the recommendations for NIC or switch interface speed
(see next section) which can result in you being able to deploy less expensive
1 Gb/s NICs on the Cisco UCS Server for the Internet Reverse Proxy or 1 Gigabit
Ethernet Switch Infrastructure in DMZ network. For more details about
split-horizon, see
Split-Horizon Network Topology.
Note |
You may be
required to deploy 1 Gigabit Ethernet NICs configured for NIC Teaming if the
Internet Reverse Proxy usage is marginally close to the 1000 Mb/s threshold.
|
See
NIC Teaming for Bandwidth Aggregation for more details.
Bandwidth on
Cisco WebEx Meetings Server Network Interfaces
For direct
interfaces between your switching architecture and your system, we recommend
provisioning your interface NICs to the maximum speeds shown in the following
table. These speeds apply to the connectivity between the Cisco UCS Servers and
ports on head-end switches in your local switching infrastructure only. These
are the recommended speeds needed to support worst-case traffic requirements.
System
Capacity
|
NIC or
Switch Interface Speed
|
50 user
system
|
1 Gb/s
|
250 user
system
|
1 Gb/s
|
800 user
system
|
10 Gb/s
1
|
2000
user system
|
10
Gb/s2
|
1 You
may optionally choose to reduce network infrastructure costs by deploying NIC
Teaming using two or more Gigabit Ethernet NICs on the UCS Server and NIC
Teaming on the head-end switch.
2 If you have a
non-split-horizon DNS deployment, the 10 Gb/s requirement pertains to the IRP
and internal virtual machines. If you have a split-horizon DNS deployment, you
may be able to reduce the network infrastructure demands on your IRP (and DMZ
network), which can result in you being able to deploy less expensive 1 Gb/s
NICs on the Cisco UCS Server for the Internet Reverse Proxy or 1 Gigabit
Ethernet Switch Infrastructure in DMZ network, as described in the "Bandwidth
on Network Paths" section. However the 10 Gb/s speed requirement holds true for
the internal virtual machines (and internal network).
See the following
section "Bandwidth Considerations for Split-Horizon DNS Deployments" for more
information about using 1 Gb/s NICSs and Ethernet switches for a split-horizon
DNS deployment.
Assumptions for NIC Speed
Calculations:
-
The aggregate
end-user session bandwidth (1.5 Mb/s) was used to calculate the NIC speeds
shown in the preceding table.
-
The
inter-virtual machine control traffic must be free of congestion. This
especially applies to 2000 user systems and any system provisioned for high
availability. Severe congestion on virtual machine links can result in system
instability and consequent interruption of service.
-
The
connections to NAS storage, used for recording and database backup, must not be
congested.
-
Protocol
overhead and implementation inefficiencies will result in usable link bandwidth
that is significantly less than the 1 Gb/s or 10 Gb/s speed labels.
-
If a large
percentage of your traffic will hit the Internet Reverse Proxy when users log
in to meetings, you need to remember that every user connection passes twice
through the NIC on the Internet Reverse Proxy (inbound and outbound). Using the
2000 user system as an example, this means the NIC on the Internet Reverse
Proxy may be required to handle 6 Gb/s of user traffic (2000 users times 1.5
Mb/s equals 3 Gb/s, times two for inbound and outbound traffic equals 6 Gb/s).
Conservatively,
we ask that the local connections be no more than 60 percent used for end user
media traffic, allowing the remaining 40 percent to be available for other
traffic, unusual traffic bursts, and network overhead. Using the 800 user
system as an example, we estimate the end user traffic at 1.2 Gb/s for the
Admin and Media virtual machines and 2.4 Gb/s for the Internet Reverse Proxy
virtual machine. Applying the 60 percent rule, we want the NIC to be capable of
handling 2 Gb/s for the Admin and Media virtual machines (1.2 Gb/s estimated
user traffic for the Admin and Media virtual machines divided by 60 percent
estimated normal bandwidth consumption equals 2.0 Gb/s) and 4 Gb/s for the
Internet Reverse Proxy virtual machine.
Note |
The NIC speeds
shown in the preceding table do not account for bandwidth used for accessing
SAN storage. If Fibre Channel over Ethernet (FCoE) is used for a SAN
connection, it should be provisioned to use an independent network interface.
|
Bandwidth
Considerations for Split-Horizon DNS Deployments
With a
split-horizon DNS deployment, some of your users will be logging in to meetings
from the Internet and that traffic will hit the Internet Reverse Proxy, while
the majority of users who are on the internal network will be logging into
meetings without hitting the Internet Reverse Proxy. With a split-horizon DNS
deployment, if you speed up your network and segment your traffic so that most
of your traffic stays within the internal network (as opposed to hitting the
Internet Reverse Proxy), you can potentially use NIC Teaming and provision a
lower-end NIC (1 Gb/s NIC) on the Internet Reverse Proxy and provision the
switching infrastructure between the Internet Reverse Proxy and the Internet to
be 1 Gb/s, or at least lower than the recommended 10 Gb/s, for a 2000 user
system.
For example, if a
company has 100 users who want to access a 2000 port user system from the
Internet concurrently, you would need a bandwidth of 150 Mb/s (1.5 Mb/s
aggregate user session bandwidth * 100 users = 150 Mb/s). This implies that a
network infrastructure from the DMZ network to the Internet Reverse Proxy can
be 1 Gb/s Ethernet switches, and the Ethernet NIC interface on the Internet
Reverse Proxy can be 1 Gb/s, as opposed to the stated 10 Gb/s interface
requirement. Even when you factor in that the Internet Reverse Proxy sees
double the traffic (meaning its NIC would have to handle 300 Mb/s of user
traffic), applying the 60 percent rule (explained in the "Bandwidth on Cisco
WebEx Meetings Server Network Interfaces" section) translates to 500 Mb/s. A 1
Gb/s link is still sufficient, but it would not be sufficient if we assumed 250
users instead of 100 users.
Note |
The optimization
of bandwidth is only applicable for the NIC on the Internet Reverse Proxy in a
split-horizon DNS deployments.
|
For
non-split-horizon DNS deployments, you must deploy 10 Gb/s Ethernet switches
and Ethernet NIC interfaces on the Internet Reverse Proxy.