Chapter 16: Dynamic Routing Protocols
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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User-Defined Cost — OSPF uses a user-defined cost for each interface. This cost is added together for each hop when
calculating the cost of a route. This metric could be the same as number of hops if each interface along the route uses
a cost of 1.
Equal Cost MultiPath Routes
OSPF also has the concept of Equal Cost MultiPath (ECMP) routes. These are routes to the same DIP (destination IP
address) and prefix which use different next hop IPs but the same cost.
The C4/c CMTS can distribute packets across at most four ECMP routes. ECMP routes can also be used with static routes.
The C4/c CMTS bases its choice of best route on the following order of criteria:
1.
Longest prefix
2.
Route type (local, netmgmt, OSPF, RIP)
3.
Route cost
Configuring OSPF
This section outlines the tasks required to configure a network and C4/c CMTS for OSPF. The procedures and commands in
this section assume that IP addresses have already been configured for the network and OSPF interfaces. The sequence
includes:
1.
Reviewing a network diagram for interface information and architecture.
2.
Enabling OSPF globally.
3.
Configuring the network according to standard configuration parameters: set router id, hello timer, dead timer,
network type (broadcast, point-to-point, virtual link), and authentication.
4.
Verifying OSPF is running as configured.
It is beyond the scope of this document to supply recommendations for reviewing network architecture for all OSPF
configuration possibilities; however, the following sections identify the CLI commands required for basic OSPF
configuration on the C4/c CMTS.