Wan Port Auto-Negotiation; Icmp Support; Igmp Multicast - Harris CM-30 Installation & Operation Manual

NetXpress LX & CM-30 Installation & Operation Manual
Version 1, September 2010
Routes in the routing table fall into two basic categories: automatic routes and user-defined routes.
The NetXpress LX system adds automatic routes based on the interface IP addresses. These routes
are called "directly connected" routes and are present to identify local subnets. If the destination for
all NetXpress LX traffic (stream and management) is to a host on its local subnet, no user routes are
needed. In most cases, however, you need to add routes to remote networks or hosts so that the
NetXpress LX system can successfully send traffic to it. In the simplest case, if there is only one
gateway on its WAN subnet, a default route (such as 0.0.0.0/0.0.0.0 next-hop "gatewayIP") pointing
to that gateway should be added. You can manage the NetXpress LX routing table from the NetXpress
LX Home page (Section 4.3.4.2 – Forwarding Table) or via direct SNMP access of the proprietary route
management MIB (Management Information Base).
2.1.4

WAN Port Auto-negotiation

The auto-negotiation mechanism accommodates multi-speed Ethernet network devices. Auto-
negotiation occurs when a physical connection is made between a NetXpress LX Ethernet port and an
Ethernet port on a network switch or router. During this process, the two Ethernet devices use a
protocol to determine at what speed (10 Mbps or 100 Mbps) they communicate and whether the
exchange of data occurs in a half-duplex (only one end transmits at a time) or full-duplex manner.
With the NetXpress LX system, you can enable or disable auto-negotiation for the WAN ports because
it is crucial that the link characteristics are set correctly to facilitate the transmission of stream data.
Auto-negotiation should be enabled when the network port to which the NetXpress LX system is being
connected is capable of negotiating to a mode of 100 Mbps or 10 Mbps and full-duplex operation.
When auto-negotiation is disabled, each Ethernet port is set to operate at 100 Mbps speed in full-
duplex mode, the optimum setting. If the anticipated stream data rate is low enough, the WAN port
can operate effectively at 10 Mbps. Operating the WAN port in half-duplex mode should be avoided.
Both sides of the link need to be set for auto-negotiation. If not, the NetXpress LX system configures
itself for 10 Mbps, half duplex, and streams experience dropped packets due to collision on the
Ethernet link.
The LAN port is always set to auto-negotiate. The management port can satisfy its function even when
operating at 10 Mbps in half-duplex mode.
Note: Do not operate auto-negotiation on only one side of the NetXpress LX link. To work properly,
both sides (NetXpress LX system and connecting device) must be enabled for auto-
negotiation. The NetXpress LX system does not revert to 100 Mbps full-duplex if it is
configured to auto-negotiate and the other device is manually configured for 100 Mbps full-
duplex.
2.1.5

ICMP Support

The ICMP (Internet Control Message Protocol) delivers error and control messages from hosts to
message requestors. An ICMP test may determine whether a destination is reachable. The ICMP
messages typically report errors in the processing of datagrams. Additionally, ICMP provides flow
control and first-hop gateway redirection. On the NetXpress LX WAN port, there is an option to block
ICMP error messages, but the "ping" messages are always allowed.
2.1.6

IGMP Multicast

The NetXpress LX system (or the CM-30 module in an original Intraplex system) interoperates with
multicast routers using the Internet Group Management Protocol (IGMP). The IGMP Multicast mode
involves transmission to specific hosts through IGMP routers. This scheme allows you to route specific
packets onto specific segments, thereby segregating unwanted traffic from narrow segments.
The NetXpress LX system supports IGMP v2 messages. When a "receive" multicast stream is
configured, it sends out IGMP membership reports. Similarly, when the multicast streams are deleted,
the NetXpress LX system sends out an IGMP Leave message and also responds to the membership
2-2
2 – Functional Design
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Intraplex Products