CEF and per-packet load balancing

Question

We have four OC3 links across the atlantic and I was looking for a solution which would allow load balacing across the four links on a per-packet basis (not session). The objective is both resiliency i.e. being able to handle link failures transparently & balancing the load across all the links. BGP multptah looked like the ideal soultion. However, I was told that the CEF packet based load balancing is no longer supported by CISCO. Is this correct ? Is it applicable for all models ? Are there any other potential solutions?
Appreciate a response from the experts.

Answer 1

Hello Rittick,
an MPLS pseudowire will use only one link of the 4 links based on inner MPLS label, it cannot be spread over multiple parallel links.
The MPLS pseudowire can travel within an MPLS TE LSP that can be protected by FRR.
per packet load balancing does not apply to your scenario.
You need to mark traffic of the critical application with an appropriate EXP settings. The EXP bits are copied to the outer (external) label.
On the OC-3 physical interfaces you will configure a CBWFQ scheduler providing 100 Mbps of bandwidth to traffic with specific EXP marking. This is elastic and over unused links bandwidth will be left available to other traffic.
On the LAN interface you need to mark the EXP bits in received packets using a policy-map
access-list 101 permit tcp host x.x.x.x host y,y,y,y
class CLASSIFY-BACKUP
match access-group 101
policy-map MARKER
class CLASSIFY-BACKUP
set mpls exp 3
class class-default
set mpls exp 0
int gex/y/z
service-policy in MARKER
class-map BACKUP
match mpls exp 3
policy-map SCHED-OC3
class BACKUP
bandwidth 100000
class class-default
fair-queue
int posx/y/z
service-policy out SCHED-OC3
applied on all pos interfaces.  The MPLS pseudowire will use one link only. Different pseudowires can use different OC-3 links. Load balancing of MPLS traffic is based on internal label (the VC label of the pseudowire)
Note:
you should check if it is possible to mark traffic received on the incoming interface of the pseudowire otherwise you need to mark IP precedence nearer to the host.
Hope to help
Giuseppe