---

Defining the Topology

CGTP provides reliable transport by duplicating packets and sending the duplicates along two networks, where one of these networks is redundant. For an overview of CGTP, see “Cluster Addressing and Networking” and “Carrier Grade Transport Protocol” in the Netra High Availability Suite 3.0 1/08 Foundation Services Overview.

Before configuring standalone CGTP, choose your topology. To minimize data loss, use a star topology as shown in FIGURE 1-1. This topology uses two identical, but physically distinct, redundant-100 Mbps networks around switches.

Hubs can be used instead of switches, but using hubs might impact CGTP performance by increasing the collision rate and network latency. CGTP can be used to remove single points of failure. However, if redundant routes share switching equipment or communication links, these common network components might constitute single points of failure.

IP over ATM or IP over CompactPCI can be used with standalone CGTP because both mediums support the IP protocol. However, depending on the selected medium, standalone CGTP might not support broadcasts.

Avoid using IP gateways between nodes because gateways might introduce unpredictable latencies and additional packet fragmentation.

Packets that are sent to a CGTP address are replicated by CGTP. The mtu value represents the maximum size of packets that you can send without fragmenting the packets. For CGTP, to avoid asymmetry when fragmenting, the mtu value on the redundant physical networks must be the same for each interface.

Duplicate packets that reach the CGTP destination address are filtered by the filtering module.

For the filtering module to be active on the Solaris OS, the ndd variable ip_cgtp_filter must be set to 1. Filtering only occurs when this value is set to 1. On Linux, however, the filtering module is activated by configuring the CGTP packet filtering rule in the table mangle using the iptables command. To verify that the filter is active, ensure that the ip_cgtp_filter -L -t mangle command lists the CGTP filtering rule.

---

Installation Prerequisites

Hardware requirements	Two network interface cards per server
Operating system	Solaris 9 and 10 Operating Systems
Software requirements	CGTP packages and patches from the Netra HA Suite software distribution See Standalone CGTP Patches and Package.
Disk capacity	Minimum 1.5 Gbytes for the Solaris distribution
Free space	Minimum 1.5 Gbytes after the Solaris Operating System has been installed