Link Configuration Parameters; Bundle Validation And Configuration Guidelines - Juniper JUNOSE SOFTWARE 11.2.X - LINK LAYER CONFIGURATION GUIDE 7-7-2010 Configuration Manual

Copyright © 2010, Juniper Networks, Inc.
For a list of the line modules and corresponding IOAs that support MLPPP fragmentation
and reassembly on the E120 and E320 routers, see E120 and E320 Module Guide,
Appendix A, IOA Protocol Support.

Link Configuration Parameters

The parameters for MLPPP fragmentation and reassembly are configured on a per-link
basis for each link interface (also known as a member link) in an MLPPP bundle.
By default, fragmentation and reassembly are disabled for MLPPP links. You can enable
or disable fragmentation and reassembly for an individual link, or for all member links in
a bundle, by using the ppp fragmentation and ppp reassembly commands. However,
you must configure the same fragmentation setting and the same reassembly
setting—enabled or disabled—for all member links in a bundle.
When you use the ppp fragmentation command to enable fragmentation on a link, you
can optionally specify the maximum fragment size to be used on the link interface. When
you use the ppp reassembly command to enable reassembly on a link, you can optionally
specify the administrative multilink maximum received reconstructed unit (MRRU) value
for the link.

Bundle Validation and Configuration Guidelines

When you configure MLPPP, the router validates that each link interface attempting to
join a statically or dynamically created bundle has Link Control Protocol (LCP) parameters
that are compatible with the other member links already in the bundle. This validation
includes examining the parameters configured for fragmentation and reassembly on a
particular link interface and verifying that these parameters are compatible with the
other member links in the bundle.
To ensure that the bundle validation succeeds, make sure you observe the following
configuration guidelines for MLPPP fragmentation and reassembly.
Guidelines for MLPPP Fragmentation
Use the following guidelines when you configure MLPPP fragmentation on a link interface:
Configure the same fragmentation setting—enabled or disabled—for all member links
in a bundle.
When fragmentation is enabled, configure the same fragment size for all member links
in a bundle.
Make sure a link's fragment size does not exceed its maximum transmission unit (MTU)
size.
Do not configure both MLPPP fragmentation (with the ppp fragmentation command)
and IP fragmentation of L2TP packets (with the ip mtu command) on the same
interface. Instead, you must choose only one of the fragmentation configurations by
setting it to the necessary value and set the other fragmentation configuration to the
maximum allowable value.
Guidelines for MLPPP Reassembly
Use the following guidelines when you configure MLPPP reassembly on a link interface:
Chapter 9: Configuring Multilink PPP
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