ZyXEL Communications P-793H User Manual

Chapter 5 WAN Setup

P-793H User’s Guide

The following table describes the labels in this screen. 

Table 17   WAN > Internet Connection > Advanced Setup

RIP & Multicast 

Setup

RIP Direction

RIP (Routing Information Protocol, RFC 1058 and RFC 1389) allows a router to 

exchange routing information with other routers. The RIP Direction field controls 

the sending and receiving of RIP packets. Select the RIP direction from Both/In 

Only/Out Only/None. When set to Both or Out Only, the ZyXEL Device will 

broadcast its routing table periodically. When set to Both or In Only, it will 

incorporate the RIP information that it receives; when set to None, it will not send 

any RIP packets and will ignore any RIP packets received.

RIP Version

This field is enabled if RIP Direction is not None. The RIP Version field controls 

the format and the broadcasting method of the RIP packets that the ZyXEL Device 

sends (it recognizes both formats when receiving). RIP-1 is universally supported 

but RIP-2 carries more information. RIP-1 is probably adequate for most networks, 

unless you have an unusual network topology. Both RIP-2B and RIP-2M sends the 

routing data in RIP-2 format; the difference being that RIP-2B uses subnet 

broadcasting while RIP-2M uses multicasting. Multicasting can reduce the load on 

non-router machines since they generally do not listen to the RIP multicast address 

and so will not receive the RIP packets. However, if one router uses multicasting, 

then all routers on your network must use multicasting, also.

Multicast

IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to 

establish membership in a multicast group. The ZyXEL Device supports both IGMP 

version 1 (IGMP-v1) and IGMP-v2. Select None to disable it.

ATM QoS

ATM QoS Type

Select CBR (Constant Bit Rate) to specify fixed (always-on) bandwidth for voice or 

data traffic. Select UBR (Unspecified Bit Rate) for applications that are non-time 

sensitive, such as e-mail. Select VBR (Variable Bit Rate) for bursty traffic and 

bandwidth sharing with other applications. 

Peak Cell Rate

Divide the DSL line rate (bps) by 424 (the size of an ATM cell) to find the Peak Cell 

Rate (PCR). This is the maximum rate at which the sender can send cells. Type the 

PCR here.

Sustain Cell Rate The Sustain Cell Rate (SCR) sets the average cell rate (long-term) that can be 

transmitted. Type the SCR, which must be less than the PCR. Note that system 

default is 0 cells/sec. 

Maximum Burst 

Size

Maximum Burst Size (MBS) refers to the maximum number of cells that can be 

sent at the peak rate. Type the MBS, which is less than 65535. 

PPPoE 

Passthrough

This field is only effective for PPPoE connections.
In addition to the ZyXEL Device's built-in PPPoE client, you can enable PPPoE 

Passthrough to allow up to ten hosts on the LAN to use PPPoE client software on 

their computers to connect to the ISP via the ZyXEL Device. Each host can have a 

separate account and a public WAN IP address.
PPPoE pass through is an alternative to NAT for applications where NAT is not 

appropriate. 
Disable PPPoE passthrough if you do not need to allow hosts on the LAN to use 

PPPoE client software on their computers to connect to the ISP.

MTU

Maximum Transmission Unit. Type the maximum size of each data packet, in 

bytes, that can move through this interface. If a larger packet arrives, the ZyXEL 

Device divides it into smaller fragments. Allowed values are 512 - 1500. Usually, 

this value is 1500.

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