Lucent Technologies DEFINITY Enterprise Communications Server Release 8.2 Administration For Network Connectivity Instructions Manual

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1  Networking Overview
Valid subnet masksThe valid subnets for each Class of address are:
Notice that all 5 valid Class C subnet masks can also be valid Class B or Class A 
subnet masks, and all 13 valid Class B subnet masks can also be valid Class A subnet 
masks.
For example, 
255.255.255.224 is a valid subnet mask for all three address 
classes. It allows 6 (2
3-2) subnetworks for Class C addresses, 2046 (211-2) 
subnetworks for Class B addresses and 524,286 (219-2)subnetworks for Class A 
addresses. Each of these subnetworks can have 30 (25-2) hosts.
Class A 
(default 255.0.0.0)Class B: 
(default 255.255.0.0)Class C 
(default 255.255.255.0)
255.192.0.0 255.255.192.0 255.255.255.192
255.224.0.0 255.255.224.0 255.255.255.224
255.240.0.0 255.255.240.0 255.255.255.240
255.248.0.0 255.255.248.0 255.255.255.248
255.252.0.0 255.255.252.0 255.255.255.252
255.254.0.0 255.255.254.0
255.255.0.0 255.255.255.0
255.255.128.0 255.255.255.128
255.255.192.0 255.255.255.192
255.255.224.0 255.255.255.224
255.255.240.0 255.255.255.240
255.255.248.0 255.255.255.248
255.255.252.0 255.255.255.252
255.255.254.0 
255.255.255.0 
255.255.255.128  
255.255.255.192 
255.255.255.224 
255.255.255.240 
255.255.255.248 
255.255.255.252  
						

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Default Gateway
On LANs that connect to other networks or subnetworks, it is convenient to define a 
default gateway node. The default gateway node is usually a router that is connected 
to 2 or more different (sub)networks. It could also be a C-LAN ethernet port that is 
connected to other C-LANs on the same switch. Any packets addressed to a different 
(sub)network, and for which no explicit IP route is defined, are sent to the default 
gateway node. The default gateway node is either directly connected to the addressed 
node or knows of another router that knows how to get to the packet address.
A default gateway can be assigned to a node (C-LAN port or IP Interface port) on the 
IP Interfaces screen. If you do not assign a default gateway to a node, an explicit host 
IP route must be defined to enable communications to any node on a different 
(sub)network.
You can also assign a default gateway by setting up an IP route with the default node 
as the destination and the router (or C-LAN) as the gateway. The default node is a 
display-only entry on the Node Names screen with IP address 0.0.0.0. It acts as a 
variable that takes on unknown addresses as values. When the “default” IP route is set 
up, any address not know by C-LAN is substituted for the default address in the 
default IP route, which uses the router as the “default” gateway. 
!SECURITY ALERT:
A default gateway could allow unauthorized access to your network if it 
is not properly administered and maintained. 
						

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When to use IP routes
You need to define IP routes only in special cases when default gateways are not 
defined or when you want to limit communication between nodes. This section 
describes the network configurations that require explicit IP routes.
The following table summarizes when you would use IP routes:
The host and network route types are not specified directly. The system implies the 
type from the specified destination IP address and its associated subnet mask. The 
route type is displayed on the IP Routing screen for the display, list, and modify 
commands.
The endpoint nodes are on the same subnet if the following three conditions are met:
•the endpoints are on the same physical subnetwork
•the Subnet Mask field is assigned the same value on the IP Interface 
screens for the two endpoint nodes 
•the network + subnet portions of the IP addresses (as determined by the 
subnet mask) are the same
See Subnetting  (page 16) for more information about subnet masks. Connection 
Ty p eWhen IP Routes are Needed:
EthernetThe endpoints are on different subnets and no default 
gateway is defined on the IP Interfaces screen for the 
local node, and
•You want the local node to communicate with only 
the specified node on a remote subnet (this is a 
host route type), or
•You want the local node to communicate with any 
node a remote network but not with nodes on other 
networks (this is a network route type)
PPPThere are one or more intermediate nodes between 
endpoints. 
						

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IP Routing ScreenThe following diagram shows the IP Routing screen.
To set up an IP route, enter the node names for the destination and the gateway, and 
enter the slot location of the C-LAN on the local switch. The destination and gateway 
node names and their associated IP addresses must be specified on the Node Names 
screen. 
The Route Type is a display-only field that appears on the screen for the display, list, 
and change ip-route commands. This field indicates whether the route is a host or 
network route. It is a host route if the destination address (associated with the 
Destination Node on the Node Names screen) is the address of a single host, or node. 
It is a network route if the destination address is the address of a network, not a single 
node.
An IP address for a network has the network ID in the network portion and 0 in the 
host portion. For example, 192.168.1.0 is the network address for the 192.168.1 
network. 
When a network is subnetted, and you want to set up a network IP route to a 
subnetwork, the IP address of the subnetwork is the first address in that subnetwork, 
which has all 0’s for the host portion of the address. For example, the subnet mask 
formed by using 2 bits of the host portion of a Class C address is 255.255.255.192 
(1100000 = 192). For the 192.168.1 network, this subnet mask creates 2 usable 
subnetworks whose IP addresses are 192.168.1.64 (0100000 = 64) and 192.168.1.128 
(1000000 = 128), with 62 usable host addresses in each subnetwork.
If you wanted the local C-LAN node to be able to communicate with the nodes on the 
192.168.1.64 subnetwork and not with others, you could do the following:
1  Leave blank the Gateway Address field on the IP Interfaces screen.
2  Enter a node name — for example, “subnet-1” — and the IP address, 
192.168.1.64, on the Node Names screen.
3  Set up an IP route with “subnet-1” in the Destination Node field.
See the description of the subnet mask in Subnetting  (page 16) for more information 
on subnet addresses. See IP Routing  (page 251) in Appendix A for a description of 
the Metric field.
display ip-route 1 Page   1 of   1 
IP ROUTING 
     Route Number: 1 
 Destination Node: clan-a2_ ___
          Gateway: router-1        C-LAN Board: 1b01 
 Metric: 0 
Route Type: host  
						

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IP Route Examples PPP Connections
The diagram below shows three switches in a DCS network with PPP signaling 
connections between switches A & B and between switches A & C. All nodes in this 
diagram are C-LAN ports. PPP data modules are administered between nodes 1 & 2 
on switches A & B, and between nodes 3 & 4 on switches A & C. With these 
connections, switch A can communicate with switches B and C without using the IP 
Routing screen to administer explicit host IP routes. However, switches B and C need 
host IP routes to communicate with each other because they are not directly 
connected.
The IP routes needed between nodes for this example are listed in the following table. 
The Destination Node and Gateway Node columns in the table show the nodes that 
you would enter on the IP Routing screen to administer a host IP route. On the IP 
Routing screen, you would enter the node names assigned on the Node Names screen 
for these nodes.
Note:(1) The PPP data modules on switches B and C for the connections to A 
must be enabled before the IP routes can be administered.
Note:(2) Nodes 2 and 3 in this example are two ports on the same C-LAN 
board. Messages from node 1 destined for node 4 arrive at node 2; the 
C-LAN ARP software routes the messages to node 4 through node 3. SwitchNode 
ConnectionsDestination 
Node 
Gateway 
NodeRoute 
Ty p eComments
B1 —> 4 4 2host IP route needed 
because there is an 
intermediate node 
between nodes 1 & 4.
C 4 —> 1 1 3host IP route needed 
because there is an 
intermediate node 
between nodes 4 & 1.
1
4
2
DCS Signaling over PPP
3SW C
SW AC-LANDS1
C-LANDS1
C-LANDS1
SW B
ppp
ppp 
						

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PPP with Ethernet Connections
The diagram below shows two interconnected (sub)networks. There are three 
switches in a DCS network with a ppp signaling connection between switches A & B 
and an ethernet signaling connection between switch A and the adjunct. Switches A 
& B and the adjunct are on one (sub)network and switch C is on another 
(sub)network. 
Switch A acts as a gateway to convert between the two signaling protocols. PPP data 
modules are administered between nodes 1 & 3 on switches A & B and ethernet data 
modules are administered on switches A & C for the C-LAN ethernet port interfaces 
to their LANs. With these connections, switch A can communicate with switch B and 
with the adjunct without using the IP Routing screen to administer explicit IP routes. 
Normally, node 5 would be defined as the default gateway for node 2 on the IP 
Interfaces screen, which would enable switch A to communicate with switch C 
without an explicit IP route defined. However, if node 5 is not assigned as the default 
gateway for node 2, switch A needs an IP route to communicate with switch C 
because these switches are on different (sub)networks. Similarly, node 6 would 
normally be defined as the default gateway for node 7; if not, switch C needs an IP 
route to communicate with switch A.
Also, switch B needs an IP route to communicate with switch C because B is 
connected to A via ppp and there are intermediate nodes between B & C.
Wan
or
IntranetC-LANDS1
2
567
DCS Signaling over Ethernet / Internet
SW ASW B
SW C
DCS Signaling over PPP3
C-LANDS1
C-LANDS1
Network 2 Network 1 PPP
Ethernet
Ethernet
Adjunct
4
LAN
LAN
1 
						

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The following table shows the IP routes needed if nodes 5 and 6 are not defined as 
default gateways for nodes 2 and 7, respectively.
SwitchNode 
ConnectionsIP Route 
Destination 
NodeIP Route 
Gateway 
NodeComments
A2 —> 7 7 5IP route needed because nodes 2 
& 7 are on different subnets and 
the Gateway Address field for the 
node-2 C-LAN is blank on the IP 
Interfaces screen.
B3 —> 4 4 1IP route needed because 3 is 
connected to 1 via ppp and there 
are intermediate nodes between 3 
& 4. The data module for the ppp 
connection between nodes 3 and 1 
must be enabled before 
administering this route.
3 —> 7 7 1IP route needed to because 3 is 
connected to 1 via ppp and there 
are intermediate nodes between 3 
& 7. The data module for the ppp 
connection between nodes 3 and 1 
must be enabled before 
administering this route.
C7 —> 4 4 6IP route needed because nodes 4 
& 7 are on different subnets and 
the Gateway Address field for the 
node-7 C-LAN is blank on the IP 
Interfaces screen.
7 —> 2 2 6IP route needed because nodes 2 
& 7 are on different subnets and 
the Gateway Address field for the 
node-7 C-LAN is blank on the IP 
Interfaces screen.
7 —> 3 3 2IP route needed because nodes 3 
& 7 are on different subnets. This 
route depends on route 7—>2.
Note: this route would not be 
needed if node 6 is administered 
for proxy ARP to act as a proxy 
agent for node 3. 
						

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Ethernet-only Connections
The diagram below shows three interconnected (sub)networks. There are three 
switches in a DCS network with ethernet signaling connections between them. 
Switches A & B and the adjunct are on one (sub)network and switch C is on another 
(sub)network. Nodes 1, 2, and 6 are C-LAN ports. Node 3 is the adjunct interface port 
to the LAN. Nodes 4, 5, and 7 are interfaces to the WAN/Internet cloud and have IP 
addresses that are on different (sub)networks. An ethernet data module and IP 
Interface is administered for the C-LAN ethernet port on each switch.
Switches A and B can communicate with each other and with the adjunct without 
using the IP Routing screen to explicitly administer host IP routes. Normally, node 4 
would be defined as the Gateway Address for node 1 on the IP Interfaces screen, 
which would enable switch A to communicate with switch C without an explicit host 
IP route defined. However, if node 4 is not assigned as the Gateway Address for node 
1, switch A needs an IP route to communicate with switch C because these switches 
are on different (sub)networks. Similarly, node 5 would normally be defined as the 
default gateway for node 6; if not, switch C needs an IP route to communicate with 
switch A.
In this configuration, network IP routes could be used alone, or in combination with 
host IP routes, to tailor access among nodes. For example, if you wanted node 1 to be 
able to communicate with any node on (sub)networks 2 and 3, you would define node 
4 as the Gateway Address for node 1. Then you would not need any IP routes defined 
for node 1. If you wanted node 1 to be able to communicate with all nodes on 
(sub)network 3 but none on (sub)network 2, you would define a network IP route to 
(sub)network 3 (and not assign node 4 as the Gateway Address for node 1). Then 
node 1 could communicate with any node on (sub)network 3 without defining host IP 
routes to them.
Router(s)
&
WANC-LANDS1
2
456
1C-LANDS1
Adjunct
Network 2
3
DCS Signaling over Ethernet / Internet
Network 1SW ASW B
SW C
C-LANDS1
Network 3
7
192.168.1.0 192.168.2.0 
192.168.3.0 
LAN
LAN
LAN 
						

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The following table shows the IP routes needed if node 4 is not defined as the 
Gateway Address (on the IP Interfaces screen) for nodes 1, 2, and 3 but node 5 is 
defined as the Gateway Address for node 6.
SwitchNode 
Connec-
tionsIP Route 
Destination 
NodeIP Route 
Gateway 
NodeRoute 
Ty p eComments
A1 —> 6 6 4 hostIP route needed because 
nodes 1 & 6 are on different 
subnets and no Gateway 
Address is specified for the 
node-1 C-LAN on the IP 
Interfaces screen.
1—>
network 3network-3 4 networkThis route enables node 1 to 
communicate with any node 
on Network 3. The node 
name network-3 must be 
associated with the IP 
address 192.168.3.0 on the 
Node Names screen.
B2 —> 6 6 4 hostIP route needed because 
nodes 2 & 6 are on different 
subnets and no Gateway 
Address is specified for the 
node-1 C-LAN on the IP 
Interfaces screen.
CNo IP routes are needed on 
Switch C because node 5 is 
defined as the Gateway 
Address for node 6. 
						

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