Multilink PPP
Multilink PPP (MLP) allows connections
over multiple links to have the same remote network address,
therefore allowing packet fragmentation and dynamic load balancing
across the links. MLP can be configured for async
,
bri
, and pri
interfaces. In
this example, we have two ports (modems) dedicated to one connection.
The traffic is distributed across both links, resulting in a
higher-bandwidth connection. We use the
dialer
load-threshold
command to tell the router to bring up the second link whenever the
first link is at 100% capacity. In this case, it says to bring up the
other link whenever either one of the interfaces reaches 100%
capacity:
interface async 1 no ip address encapsulation ppp dialer rotary-group 1 ! interface async 2 no ip address encapsulation ppp dialer rotary-group 1 ! interface dialer 1 ip unnumber ethernet 0 encapsulation ppp dialer in-band dialer load-threshold 100 either ppp authentication chap ppp multilink
Multilink PPP is commonly used to tie the two channels of a BRI ISDN
line into a single 128-Kbps connection. Here’s what that
configuration looks like. We define two ISDN interfaces, one for
each B channel; we place those interfaces in the same rotary group;
then we configure a dialer interface for the rotary group using PPP
encapsulation. The dialer interface has the
multilink
command, which allows you to use both
BRI interfaces simultaneously:
interface BRI0 no ip address encapsulation ppp dialer idle-timeout 300 dialer rotary-group 1 ...
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