User`s guide

Chapter 4 Broadband
ericom D1000 modem User’s Guide
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LLC-based Multiplexing
In this case one VC carries multiple protocols with protocol identifying information being contained
in each packet header. Despite the extra bandwidth and processing overhead, this method may be
advantageous if it is not practical to have a separate VC for each carried protocol, for example, if
charging heavily depends on the number of simultaneous VCs.
4.5.3 VPI and VCI
Be sure to use the correct Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) numbers
assigned to you. The valid range for the VPI is 0 to 255 and for the VCI is 32 to 65535 (0 to 31 is
reserved for local management of ATM traffic). Please see the appendix for more information.
4.5.4 IP Address Assignment
A static IP is a fixed IP that your ISP gives you. A dynamic IP is not fixed; the ISP assigns you a
different one each time. The Single User Account feature can be enabled or disabled if you have
either a dynamic or static IP. However the encapsulation method assigned influences your choices
for IP address and ENET ENCAP gateway.
IP Assignment with PPPoA or PPPoE Encapsulation
If you have a dynamic IP, then the IP Address and Gateway IP Address fields are not applicable
(N/A). If you have a Static IP Address assigned by your ISP, then they should also assign you a
Subnet Mask and a Gateway IP Address.
IP Assignment with RFC 1483 Encapsulation
In this case the IP address assignment must be static.
IP Assignment with ENET ENCAP Encapsulation
In this case you can have either a static or dynamic IP. For a static IP you must fill in all the IP
Address and Gateway IP Address fields as supplied by your ISP. However for a dynamic IP, the
Device acts as a DHCP client on the WAN port and so the IP Address and Gateway IP Address
fields are not applicable (N/A) as the DHCP server assigns them to the Device.
4.5.5 Nailed-Up Connection (PPP)
A nailed-up connection is a dial-up line where the connection is always up regardless of traffic
demand. The Device does two things when you specify a nailed-up connection. The first is that idle
timeout is disabled. The second is that the Device will try to bring up the connection when turned
on and whenever the connection is down. A nailed-up connection can be very expensive for obvious
reasons.
Do not specify a nailed-up connection unless your telephone company offers flat-rate service or you
need a constant connection and the cost is of no concern.