The MPLS-OPS Archive

["Balaji Chandrasekaran" <balaji.c@ntt.com>]

Hi!!

In cisco in the P-Routers you run CEF switching. When you run CEF there are
2 types of Load Balancing. One is per destination Load Balancing ( Cisco
Default ) and per packet load Balancing. The advantage of running per
destination load balancing
the CPU utilization is lesser than the per packet loadbalancing.

In per destination load balancing it builds an FEC and uses the same link to
transfer all the packets to that destination from particular source(may be
particular label). The router automatically alternates and load balances the
link to different destinations.

In per packet load balancing it has to load balance between equal cost links
even for the same destination/source pair.

You can change the behaviour by giving the ip load-sharing per-packet on the
interface configuration mode.

Cisco recommends per-destination load balancing unless there is some
specific reason for changing the default behaviour.

Balaji.

----- Original Message -----
From: "LIAN Franklin FTLD/IAP" <franklin.lian@francetelecom.com>
To: <mpls-ops@mplsrc.com>
Sent: Monday, January 28, 2002 11:58 PM
Subject: Load-balancing in MPLS core


> Hello,
>
> Is there anybody from Cisco can explain how the implementation of
> load-balancing is done on the P router in MPLS core?  Let's say
> we have MPLS L3 VPN and MPLS L2 VPN in place, my question is how
> the P router provides load-balancing between two customer sites
> if two or more equal paths between the two sites exist on a given
> P router?
>
> My understanding is that the load-balancing is provided solely
> based on the LSP(s) built in between the ingress PE and egress PE,
> and it has nothing to do what is encapsoluated inside the label
> packet because the P router has no idea of the VPN routes.
> I will appreciate if somebody on the list can correct me if I am
> wrong.
>
> Thanks in advance,
> Franklin
>
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