Load Balancing per packet not working properly

[salman-ahmad]

Hi,

I am attaching you the configs of issue. There are two links E1 links from

Karac-1(Serial0/0/0:0 & 0:1) and Karac-2 with (Tunnel10) which were connected with Khask-1w

Now the issue is that Load balancing per packet were not done sucessfully the NMS snap shot is already attached.

Load balancin g only configured in KarAC-1 & 2

What is the resolution of this problem traffic only use on two links but third links were not utilize.

Kind regards,Salman Ahmed

[shillings]

Per-packet load sharing is not enabled on PK-KHASK-1, either globally or on the E1s.

Provided there are two or more equal cost routes in the IP Routing Table, then you can confirm the type of load balancing IP CEF will perform. For example, if you had two equal cost default routes, then you'd enter  show ip cef 0.0.0.0 0.0.0.0   and the output should read  per-packet sharing  followed by a list of each next hop.

What equal cost route are you load balancing from PK-KHASK-1 to PK-KHASK-2? Are the two routes being learned via OSPF? There are certainly no static routes configured on PK-KHASK-1 to achieve this.

Why is per-packet load sharing unabled on the PK-KHASK-2 tunnel?

[paolo bevilacqua]

With per-packet load sharing, you are causing out-of-order packet arrival (a very bad thing), and that means destroying application performances.

Either use regular per-flow load sharing, or use multilink PPP.

[24madaeve1]

Hi Paolo!

I have one doubt pertaining to per-packet load-sharing. In order to connect my two data-centres- A & B, Site A is having two WAN links and Site B is having two WAN links - one from ISP1 (30Mbps link) and the other from ISP2 (50Mbps link). I am doing static route load balancing using same AD values for both the ISPs. I have configured "ip load-sharing per-packet" on both the outgoing interfaces.

The load is getting distributed equally across both the links but total bandwidth utilization across both the links is not going beyond 30Mbps. The combined bandwidth of both links is 80Mbps (50+30). However links are not getting fully utilized even though heavy load is there on the links. Can you please tell me how to make full use of both the wan links at both the ends? OR Can you tell me how I can distribute the traffic across both the links with full utilization without using per-packet load sharing. Moreover, my links can be configured statically only at both the ends.

[paolo bevilacqua]

As mentioned before, with per-packet load sharing the performance will be horrible because out-of-order packet arrival, so leave the default of per-flow. 

The distribution will be be statistical, not perfect, but each flow will enjoy the best performances.

[24madaeve1]

Hi Paolo, as far as I know, default is per-packet load sharing. But that leads to 100% utilization of one WAN link while the other is idle. Can you recommend any scheme for getting the load shared across both the WAN links without any out-of-order delivery or jitter and decent utilization across both the links.

[paolo bevilacqua]

Default is per-flow load sharing. That is also the only method for optimal link utilization and application performance.