Nortel Networks Recording Equipment 1 사용자 설명서
Voice over Wireless LAN Solution Guide
v1.0
December 2005
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Page 14
Figure 3: Branch Office architecture
2.2.1.4 Combining
architectures
Up to now, architecture has been discussed in binary terms—this topology or that topology.
However, the WLAN 2300 solution is not restrictive in this way. The three architectures can be
combined in many different ways within the same network, and as will be shown later, VoWLAN
is generally not restricted by these architectural choices. However, it is a good practice from a
supportability standpoint to maintain a level of consistency in architectural choices. Figure 4
depicts all three architectures in one network, although this design example should not be
considered a reference architecture or a best practices diagram. In this network, both the
distributed and centralized WSSs are deployed as a single Mobility Domain, which is defined as a
collection of WSSs that work together to support a roaming user.
However, the WLAN 2300 solution is not restrictive in this way. The three architectures can be
combined in many different ways within the same network, and as will be shown later, VoWLAN
is generally not restricted by these architectural choices. However, it is a good practice from a
supportability standpoint to maintain a level of consistency in architectural choices. Figure 4
depicts all three architectures in one network, although this design example should not be
considered a reference architecture or a best practices diagram. In this network, both the
distributed and centralized WSSs are deployed as a single Mobility Domain, which is defined as a
collection of WSSs that work together to support a roaming user.
As a general rule, branch office WSSs are either in a separate Mobility Domain, if there are
multiple switches, or in a null Mobility Domain. They should not be part of the main campus
Mobility Domain, as users do not need seamless roaming between the sites. Also not desirable is
unnecessary loading of the WAN link due to the overhead associated with Mobility Domain
statistics collection and remote VLAN connectivity. When choosing whether to include the branch
office WSSs in the main campus Mobility Domain, base your decision on both geography (Do the
sites have seamless RF coverage between them?) and WAN speeds (Is there enough bandwidth
to support users with remote VLAN assignments?). If you decide to backhaul a remote site’s
users to the campus Mobility Domain, you will need at least a T1 speed link, but you could require
higher speed depending on the numbers of users and application requirements. Within an
isolated branch office, if there is only one WSS, then no Mobility Domain needs to be defined. If
there is more than one WSS, then group them together in a unique Mobility Domain.
multiple switches, or in a null Mobility Domain. They should not be part of the main campus
Mobility Domain, as users do not need seamless roaming between the sites. Also not desirable is
unnecessary loading of the WAN link due to the overhead associated with Mobility Domain
statistics collection and remote VLAN connectivity. When choosing whether to include the branch
office WSSs in the main campus Mobility Domain, base your decision on both geography (Do the
sites have seamless RF coverage between them?) and WAN speeds (Is there enough bandwidth
to support users with remote VLAN assignments?). If you decide to backhaul a remote site’s
users to the campus Mobility Domain, you will need at least a T1 speed link, but you could require
higher speed depending on the numbers of users and application requirements. Within an
isolated branch office, if there is only one WSS, then no Mobility Domain needs to be defined. If
there is more than one WSS, then group them together in a unique Mobility Domain.
In general, most combined architectures are either Centralized Campus plus Branch Office or
Distributed Campus plus Branch Office. There is little motivation for combining Centralized
Campus and Distributed Campus in the same site, although there are some scenarios for mixing
architectures on individual sites. For example, a large campus may deploy WSS 2380s to support
the numbers of APs needed, a medium-size regional office may be big enough to deploy a
handful of WSS 2360s but not big enough to need a WSS 2380, and smaller branches might
employ WSS 2350s.
Distributed Campus plus Branch Office. There is little motivation for combining Centralized
Campus and Distributed Campus in the same site, although there are some scenarios for mixing
architectures on individual sites. For example, a large campus may deploy WSS 2380s to support
the numbers of APs needed, a medium-size regional office may be big enough to deploy a
handful of WSS 2360s but not big enough to need a WSS 2380, and smaller branches might
employ WSS 2350s.