SmartWare Software Configuration Guide

30 • PPP configuration

 

 

Step

Command

Purpose

 

 

 

3

node(if-ip)[name]#ipaddress

The PPP remote peer offers an IP address for the

 

unnumbered

IP interface. The IP interface adopts this IP

 

or

address

 

 

 

node(if-ip)[name]#ipaddress dhcp

Once PPP has established an IP connection, the

 

 

IP interface can use DHCP to acquire an IP

 

or

address. It sends a DHCP Discover message

 

 

(which is an IP broadcast) to the IP network to

 

 

which PPP has established connection. If no

 

 

DHCP Server is present, the IP interface does

 

 

not adopt the IP address offered by the PPP

 

 

remote peer but leaves the IP address unde-

 

 

fined.

 

node(if-ip)[name]# ipaddress ip-address

The IP interface requests from the PPP remote

 

netmask

peer to use the IP address ip-address. PPP

 

 

repeatedly tries to set-up a connection until the

 

 

remote peer accepts this IP address. It does not

 

 

accept any other IP address offered by the PPP

 

 

remote peer. The parameter netmask specifies

 

 

the size of the subnet in case ‘no point-to-point’

 

 

is configured

 

 

 

4

node(if-ip)[name]# [no] tcp adjust-mss {

Limits to the MSS (Maximum Segment Size) in

(optional)

rx tx } { mtu mss }

TCP SYN packets to mss or to MTU (Maximum

 

 

Transmit Unit) - 40 Bytes, if ‘mtu’ is used. ‘rx’

 

 

applies to packets which arrive inbound at this

 

 

IP interface, ‘tx’ to packets which leave out-

 

 

bound of this IP interface.

 

 

PPP over Ethernet connections impose an over-

 

 

head of 8 Bytes (PPP: 2 Bytes, PPPoE: 6 Bytes).

 

 

Some Ethernets do not allow payloads larger

 

 

than the 1500 Bytes which the standard

 

 

defines, so IP packets must not contain more

 

 

than 1492 bytes when transmitted over such

 

 

connections. Reducing the MTU/MRU to 1492

 

 

Bytes does not always solve the problem

 

 

because many sources do not allow fragmenta-

 

 

tion of the IP packets they send (they set the

 

 

‘Don’t fragment’). However, these sources limit

 

 

the size of the IP packets according to the MSS

 

 

which their peers announce in the TCP SYN

 

 

packets.

 

 

It is recommended to use ‘mtu’ inbound and

 

 

outbound.

 

 

 

PPP configuration task list

316

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Patton electronic SmartNode 4110 Series manual Nodeif-ipname#ipaddress dhcp, Nodeif-ipname# ipaddress ip-address
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