22-22
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
Chapter 22 Configuring Multilink Point-to-Point Protocol Connections
MLP on LNS
Each bundle includes 256 entries. However, in a single link bundle most packets arrive in order;
therefore, fewer buffers are required per single link bundle. For example, if the average usage is 10
buffers per single link bundle, the average usage is 436.7 buffers per multilink bundle.
•
Packet processing rate
The PRE3 has a rate of 10 million contexts per second, which is the rate of contexts or packets
passing through the PXF complex. The packet processing rate is measured by the number of packets
per second that can either be enqueued or dequeued by the PRE3. If each packet takes 2 passes to
be enqueued, then the enqueue rate is 5 mcps. Because the enqueueing and dequeueing processing
is performed concurrently, the overall performance is determined by the worst case between enqueue
and dequeue as shown in the following sections.
If the packet processing demand exceeds the available contexts, nonpriority packets are dropped.
Scenario 1
•
A bidirectional rate of 64kbps per link.
Table 22-5
shows the speed performance of a 64kbps link.
•
2040 multilink bundles
•
2, 5, and 10 links per multilink bundle
•
10240 single link bundles
•
200 byte packet size in both directions
•
100 byte fragment size (fragmentation for ingress only)
Note
A fragmentation delay of 2ms requires a 16 byte fragment size. Because the MLP over L2TP
header can be on the order of 50 bytes, a 16 byte fragment size is not possible.
Table 22-5
64-kbps Link Speed Performance
This scenario shows that for 64Kbps links with a maximum bundle scaling and high-demand traffic, the
PXF can barely keep up with demand. Therefore, the total number of 64Kbps links should not exceed
20440.
Scenario 2
•
A bidirectional rate of 2mbps per link.
Table 22-6
shows the speed performance of a 2Mbps link.
•
500 and 2040 multilink bundles
•
2 and 4 links per bundle
•
No single link bundles
•
500 and 1000 byte packets in both directions
•
512 byte fragment size (fragmentation for ingress only)
Links per multilink bundle
10
5
2
Total links (multi + single)
30640
20440
18400
Total context rate (million
contexts/sec)
9.8
6.5
4.6
