Cisco 10000 - Manual (Page 437)

19-19
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
Chapter 19 Configuring Multilink Point-to-Point Protocol Connections
MLP on LNS
Figure 19-5 MLP on LNS–Single-Member Bundle
To accommodate the scaling requirements of up to 2040 multi member and 10240 single-member
bundles for the MLP on LNS feature, an additional reassembly buffer is reserved in the external column
memory (XCM). The reassembly buffer that was reserved in the Cobalt space is used for multi-member
bundles and the XCM reassembly buffer is used for single-member bundles.
The fixed reassembly table size for the MLP on LNS feature to buffer fragments is 256 entries. The
reassembly table size restricts the maximum differential delay for all of the different paths for the
member links from the CPE to the LNS. For example, if there are 10 members in a bundle, and one of
the members is associated with a “slow” (high delay) path, then the other nine members must have their
fragments/packets buffered while waiting for the slower link. Because the reassembly table stores
descriptors, each entry represents one fragment or a whole packet if fragmentation is not in effect. The
amount of time each fragment takes to get transmitted is equal to the configured fragment delay, which
is independent of link bandwidth. If fragmentation is not in effect, the transmit time depends on the
packet size, with smaller packets being slower. Therefore, the amount of tolerated differential delay is
the reassembly table buffering limit for the other 9 links:
(256 / 9) * frag_delay = 28.4 * frag_delay
Note The default differential delay for MLP on LNS is 50ms.
Table 19-4 shows the resource usage on Cisco 10000 series router.
Table 19-4 Resource Usage
270
3
26
L2TP VC
Upstream
• Reassembly of MLP Fragments
Downstream
• QoS is allowed
• MLP
• No MLP fragmentation and interleaving
Upstream
• MLP
(single-link bundle)
• MLP fragmentation
and interleaving
MLP
Single link per bundle
Cisco 10000
series router
PRE3 LNS
CPE
LAC
DSLAM
VCCI 1 HWIDB 2 SWIDB 3 PBLT 4
Cisco 10000 series
routers MAX 64000 Memory
dependent Memory
dependent 16000
Bundle interface 1 1 1 1