RFC 3069 (rfc3069) - Page 2 of 7
VLAN Aggregation for Efficient IP Address Allocation
Alternative Format: Original Text Document
RFC 3069 VLAN Aggregation for IP Address Allocation February 2001
Figure 1:
+------+ +------+ +------+ +------+ +------+
| | | | | | | | | |
| A.1 | | A.2 | | B.1 | | C.1 | | B.2 |
| | | | | | | | | |
+------+ +------+ +------+ +------+ +------+
\ | | | /
\ | | | /
\ +-----------------------------------+ /
| |
| Ethernet Switch(es) |
| |
+-----------------------------------+
|
|
+--------+
| |
| Router |
| |
+--------+
In the Figure 1 hosts A.1 and A.2 belong to customer A, VLAN A.
Hosts B.1 and B.2 belong to customer B, VLAN B. Host C.1 belongs to
customer C and resides in it's own virtual LAN, VLAN C.
Traditionally, an IP subnet would be allocated for each customer,
based on initial IP requirements for address space utilization, as
well as on projections of future utilization. For example, a scheme
such as that illustrated in Table 1 may be used.
Table 1:
Gateway Usable Customer
Customer IP Subnet Address Hosts Hosts
======== ============ ======= ====== ========
A 1.1.1.0/28 1.1.1.1 14 13
B 1.1.1.16/29 1.1.1.17 6 5
C 1.1.1.24/30 1.1.1.25 2 1
Customer A's initial deployment consists of 2 hosts, though they
project growth of up to 10 hosts. As a result, they're allocated the
IP subnet 1.1.1.0/28 which provides 16 IP addresses. The first IP
address, 1.1.1.0, represents the subnetwork number. The last IP
address, 1.1.1.15, represents the directed broadcast address. The
first usable address of the subnet, 1.1.1.1, is assigned to the
router and serves as the default gateway IP address for the subnet.
The customer is left 13 IP addresses, even though their requirement
was only for 10 IP addresses.
McPherson & Dykes Informational
