User Manual

Enterasys X-Pedition User Reference Manual 119
Chapter 9
Packet-over-SONET
Configuration Guide
Overview
This chapter explains how to configure and monitor packet-over-SONET (PoS) on the XP. See the
sonet commands section of the Enterasys X-Pedition Command Line Interface Reference Manual
for a description of each command.
PoS requires installation of the OC-3c or OC-12c PoS line cards in an XP-8000 or an XP-8600. The
OC-3c line card has four PoS ports, while the OC-12c line card has two PoS ports. You must use
the “so.” prefix for PoS interface ports. For example, you would specify a PoS port located at router
slot 13, port 1 as “so.13.1.” By default, PoS ports are set for point-to-point protocol (PPP)
encapsulation. You cannot change this encapsulation type for PoS ports.
Note: While PoS ports use PPP encapsulation, other PPP characteristics such as service profiles,
encryption, compression, and MLP bundles are not supported for PoS ports.
Note: The XP does not support PVST over POS. However, the router will support STP over
POS.
By default, PoS ports are configured to receive a maximum transmission unit (MTU) size of 1500
octets. The actual MTU size used for transmissions over a PoS link is a result of PPP negotiation.
For transmission of “jumbo frames” (MTUs up to 65442 octets), you can increase the MTU size of
the PoS port. The MTU must be set at the port level.
Configuring IP Interfaces for PoS Links
Configuring IP interfaces for PoS links is generally the same as for WANs and for LANs. You
assign an IP address to each interface and define routing mechanisms such as OSPF or RIP as with
any IP network. You can configure the IP interface on the physical port or you can configure the