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Community Member

Network Best Performance

Hi To All,

I'am Tony and would like to ask regarding on our branch office connected to the central office. for our branch office we have 6Mbps leased line connection traversing and as per my checking we used both routers and to end.

I would like to know if it is possible if we use layer instead of router for point A and B? and the gateway will be located on our Centarl office? since we are using leased line connection.

Super Bronze

Re: Network Best Performance


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It may be possible; it depends on your equipment and media.  However if the WAN link is bandwidth constrained compared to your LAN, there's often benefit to routing across the link rather than using it as L2.  This to avoid sending some traffic across the link, needlessly.

Network Best Performance

Hello, Antonio.

It's not a good idea to extend Layer2 over WAN.

At least this would lead to broadcast traffic wasting your bandwidth and you won't have an option to perform QoS on the link.

Community Member

Network Best Performance

Heloo Mikh.

What if we implement Qos on that WAN link for protocol prioritization ? do you think it will help us since we have only 6Mbps Connection?

Re: Network Best Performance

Hello, Antonio.

As far as your WAN link has much lower bandwidth than LAN, it  could be overutilized in case of traffic bursts.

So, yes, QoS could be really useful.

The simplest what you could implement is shaping on the contracted CIR.

If you plan to run VoIP over the link, or need any kind of unfair traffic prioritization, than you need to define your classes and implement CBWFQ or LLQ.


PS: surely it's worth to configure QoS on both sides of the link.

PS2: it's also worth to ask your provider if they have any kind of QoS on the link.

Community Member

Network Best Performance

Noted I'll study first the CBWFQ or LLQ

Community Member

Network Best Performance

Since this is new to me can you give me some pointer on how to implement it?

Network Best Performance

Hello, Antonio.

First of all you need to understand if you have any QoS options from your ISP (as you must be aligned to them).

Then define your applications and assign them per class.

For example, you want to have VoIP and Business class, then it will be like:


ip access-l ext VoIP_ACL

permit udp any any dscp ef

ip access-l ext BUSINESS_ACL

permit tcp any any eq 22

permit tcp any eq 22 any

permit icmp any any


class-map VoIP

match access-group name VoIP_ACL

class-map BUSINESS

match access-group name BUSINESS_ACL

policy-map QOS_POLICY

class VoIP

priority per 20

!policer could be configured as well to prevent Voice allocating more bandwidth


bandw per 60


class class-default

bandw per 19

random-detect ! or use fair-queue

policy-map QOS_INTERFACE

class class-default

  shape ave 5400000 108000 ! example for 6000000 link

  service-policy QOS_POLICY

int Gx/x

service-policy out QOS_INTERFACE


Best regards.

Community Member

Network Best Performance

Hi Mik,

Thank you for your swift response I'll test this.

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