Table of Contents
Advertisement
Overview
About IP Unicast Forwarding
IP unicast forwarding is performed on the MPLS module to facilitate implementation of
MPLS and accounting. When MPLS or accounting functions are enabled, the MPLS
module, rather than the switch fabric hardware, performs layer-3 IP unicast forwarding.
Layer-2 switching and Layer-3 IP multicast forwarding are unaffected.
The MSM distributes its IP unicast routing table, ARP table, MPLS incoming label
mappings (ILMs), FEC-to-NHFLE database, and interface IP addresses to each MPLS
module so that every MPLS module contains the same IP routing database.
Each MPLS module has sufficient capacity to support 256K IP longest prefix match
lookup route entries. Each route entry also supports up to four equal-cost paths. IP
forwarding is configurable per VLAN.
Each MPLS module IP routing database provides an aggregate IP forwarding
throughput of up to 4 Gbps. The total forwarding throughput for a single
BlackDiamond chassis can be scaled up to 16 Gbps by adding up to four MPLS
modules. MPLS modules interface to the BlackDiamond switch fabric via four 1 Gbps
internal links. IP unicast traffic is internally forwarded from the BlackDiamond I/O
modules using one of three backplane load-sharing policies: port-based, address-based,
or round-robin. See the ExtremeWare Software User Guide for more information.
About Destination-Sensitive Accounting
Destination-sensitive accounting allows you to bill your customers at different rates
depending upon the destination of the IP unicast packets they send.
Destination-sensitive accounting categorizes IP unicast packets according to two
parameters:
• The ID of the VLAN from which the packet was received
• The accounting bin number associated with the route used to forward the packet
For each category, 64-bit counts of both the number of packets and number of bytes
forwarded, including those locally delivered to the MSM CPU, are collected. Eight
accounting bin numbers, with values from 0-7, are available for each of the possible
4096 VLAN IDs. This yields a maximum of 32768 sets of accounting statistics.
1-8
MPLS Module Installation and User Guide
Advertisement
Table of Contents
