Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Configuration Manual

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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:
■
Configure the same reassembly setting—enabled or disabled—for all member
links in a bundle.
■
Make sure a link’s administrative MRRU is greater than or equal to the local
maximum receive unit (MRU) negotiated both on that link and on other member
links in the bundle.
■
The local MRRU negotiated on a link must be the same as the local MRRU
negotiated on the other member links in the bundle.
■
The peer MRRU negotiated on a link must be the same as the peer MRRU
negotiated on the other member links in the bundle.
326 ■
Configuring MLPPP Fragmentation and Reassembly
JUNOSe 11.1.x Link Layer Configuration Guide