R3303-HP HSR6800 Routers Layer 2 - WAN Configuration Guide

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• Ready—The member interface is up at the link layer and meets the conditions for being a selected
interface, but is not selected yet due to the limitation on the maximum number of selected member
interfaces, the minimum number of selected member interfaces required for bringing up the HDLC
link bundle, or the minimum amount of bandwidth required for bringing up the HDLC link bundle.
• Selected—The member interface is up at the link layer, meets the conditions for being a selected
interface, and conforms to the restrictions. Only member interfaces in this state can forward traffic.
For more information about how to determine the state of a member interface, see "How the device
deter
mines the state of a member interface."
How HDLC link bundling works
How the device determines the state of a member interface
The states of HDLC link bundle member interfaces are determined according to the following rules:
1. An interface is placed in initial state if its link layer protocol is down.
2. An interface is placed in negotiated state when its link layer protocol goes up.
3. An interface in negotiated state can transit to the selected or ready state after undergoing a
selection process. Depending on whether the device allows member interfaces having different
transmission rates to be selected at the same time, the selection process can be either of the
following:
{ If selected interfaces cannot be at different rates, those with the highest interface rate/baud rate
are selected. Suppose the number of selected member interfaces is M (those member interfaces
with lower rates/baud rates remain in the negotiated state) and the limit on the maximum
number of selected member interfaces in the HDLC link bundle is set to N: when N is no smaller
than M, all these M member interfaces stay in the selected state; when N is smaller than M,
these selected member interfaces are first sorted in the descending order of bundling priorities
and then the selected member interfaces with the same bundling priority are sorted in the
ascending order of interface numbers. The first N member interfaces stay in the selected state,
and the left (M-N) member interfaces enter the ready state.
{ If selected interfaces can be at different rates, the number of member interfaces in the
negotiated state is M, and the limit on the maximum number of selected member interfaces in
the HDLC link bundle is set to N: when N is no smaller than M on the device, all the member
interfaces in the negotiated state enter the selected state; when N is smaller than M, these
member interfaces are first sorted in the descending order of rates/baud rates, then member
interfaces with the same rate/baud rate are sorted in the descending order of bundling
priorities, and at last member interfaces with the same bundling priority are sorted in the
ascending order of index numbers. The first N member interfaces enter the selected state, and
the remaining (M-N) member interfaces enter the ready state.
The router allows member interfaces having different transmission rates to be selected at the same
time.
The maximum number of member interfaces that can be selected in a bundle is set by the bundle
max-active links command. If the command is not set, the maximum number of selected member
interfaces that the router supports for a bundle applies, which is 8.
4. Suppose the number of member interfaces meet the conditions for being selected is P. If the number
of selected member interfaces required for bringing up the HDLC link bundle is set to Q and P is
smaller than Q, none of the P member interfaces will be selected. Instead, they all stay in the ready
state. The same situation occurs when the sum of bandwidths of the P member interfaces is smaller
than the minimum amount of bandwidth required for bringing up the HDLC link bundle.