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Cisco 10000 Series Router Software Configuration Guide
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Chapter 22 Configuring Multilink Point-to-Point Protocol Connections
IP Addresses on MLP-Enabled Links
IP Addresses on MLP-Enabled Links
Configuring an IP address on a link used for MLP does not always work as expected. For example,
consider the following configuration:
interface Serial 1/0/0
ip address 10.2.3.4 255.255.255.0
encapsulation ppp
ppp multilink
You might expect the following behavior as a result of this configuration:
•
If the interface does not negotiate to use MLP and the interface comes up as a regular PPP link, then
the interface negotiates the Internet Protocol Control Protocol (IPCP) and its local address is
10.2.3.4.
•
If the interface did negotiate to use MLP, then the configured IP address is meaningless because the
link is not visible to IP while it is part of a bundle. The bundle is a network-level interface and can
have its own IP address, depending on the configuration used for the bundle.
Instead, if a link with an IP address configured comes up and joins a bundle, IP installs a route directly
to that link interface and it might try to route packets directly to that link, bypassing the MLP bundle.
This behavior occurs because IP considers an interface to be up for IP traffic whenever IP is configured
on the interface and the interface is up. MLP intercepts and discards these misdirected frames. This
condition occurs frequently if you use a virtual template interface to configure both the PPPoX member
links and the bundle interface.
Table 22-2
Bundle Name Generation
Command
Bundle Name Generation Algorithm
multilink bundle-name authenticated
The bundle name is the peer’s username, if
available.
If the peer does not provide a username, the
algorithm uses the peer’s endpoint discriminator.
Note
The
authenticated
keyword specifies that
the bundle name is based on whatever
notion of a username the system can
derive. The endpoint discriminator is
ignored entirely, unless it is the only name
that can be found.
The
multilink bundle-name authenticated
command is the default naming policy.
multilink bundle-name endpoint
The bundle name is the peer’s endpoint
discriminator.
If there is no endpoint discriminator, the
algorithm uses the peer’s username.
multilink bundle-name both
The name of the bundle is a concatenation of the
username and the endpoint discriminator.
