Alcatel Omni Switch/Router User Manual page 716

Application Example 2
In this example one Group was created – Group 3 – that includes all ports to which
ers and clients are connected. Within this Group five
VLAN B
IPX Network 10
Ethernet- II encap
When the Omni Switch/Router receives frames from the five servers, each server is assigned
to the appropriate
appropriate framing specified – so that traffic can route between the
When a client workstation boots up and queries for a server, the Omni Switch/Router assigns
the client to the appropriate
encapsulation,
the client is assigned to
F ( 802.3 encapsulation), respectively.
IPX
However, when a client workstation using Ethernet-
a server, the Omni Switch/Router initially assigns the client to both
both of these
recognizes that the client's frame is a "Get_Nearest_Server" query and remembers that the
client is in search of its network number. While the client remains in this transitional state, it
remains assigned to all
received response from a server or servers or from an intervening router, the client selects its
network number and begins transmitting frames with the network number embedded. The
Omni Switch/Router detects these frames, removes the client from all previously-assigned
network address
proper network address
IPX
Why is this Solution Recommended?
As as been explained, isolating each
recommended way to avoid conflicts. No problems occur if a client receives broadcast and
multicast traffic from multiple servers, especially for the brief period that the client remains in
a transitional state in search of a server.
Problems do occur if two servers with different network numbers and the same encapsula-
tion type are members of the same
notice conflicting network numbers for the same
tion error. For this reason it is not advisable to create four
address policies within the same Group, each configured for one of the four encapsulation
types. It is important to isolate the servers, but it is not important to isolate the clients – at
least immediately.
While it is not important to isolate
them as soon as possible. Isolating clients – rather than letting them remain in multiple
that specify the same encapsulation type – increases efficiency and reduces broadcast and
multicast traffic in the network. If a client remains in multiple
encapsulation type, the client receives all broadcast and multicast traffic from each server
using that encapsulation type, even though the client only communicates with the server that
shares its network number. In addition, when a
is wasteful and inefficient to transmit unnecessary frames across the
as soon as a client learns its network number and begins transmitting frames with that
number, the Omni Switch/Router removes the client from all previously-assigned
address
VLAN
Page 24-6
VLAN C
IPX Network 20
Ethernet- II encap
and no conflict occurs.
VLAN
(s) based on encapsulation type. If the client uses 802.2
VLAN
encapsulation, or
SNAP
D (802.2 encapsulation),
VLAN
s specify Ethernet-
VLAN II
s that specify Ethernet-
VLAN
s (but not from
VLAN
according to network number.
VLAN
Please Take Note
clients often are not particular about the server to which they
IPX
attach. However, clients can select a preferred server if the
(preferred server name) option is included in their start-up script.
IPX
VLAN
IPX
s and assigns it to a single
s were created, one for each server:
VLAN
VLAN D VLAN
IPX Network 30 IPX
802.2 encap SNAP
routing is enabled for each
IPX
802.3 encapsulation,
IPX
E (
VLAN
encapsulation boots up and queries for
II
encapsulation. However, the Omni Switch/Router
encapsulation. Once the client has
II
s of other policy types) and assigns it to the
VLAN
server in its own network address
IPX
, because each server will detect the other's frames,
, and respond with a router configura-
VLAN
VLAN
clients immediately at bootup, it is desirable to isolate
VLAN
is extended across a
VLAN
according to network number.
IPX VLAN
IPX
E VLAN
Network 40 IPX Network 50
encap IPX 802.3 encap
– with
VLAN
s.
VLAN
assignment is simple:
VLAN
encapsulation), or
SNAP
B and C, since
VLAN VLAN
/
PS
is the
VLAN
s based on network
IPX
s that specify the same
backbone, it
WAN
. For these reasons,
WAN
network
IPX
serv-
F
VLAN
IPX
s
VLAN