Port speed on Edge Internet Router

[mahesh18]

Hi Everyone.

We have Switch connected to Edge Internet Router.

Switch int g0/1 goes to gi0/1 of Edge Router.

Even though physical link is 1000 we have hardcoded speed to 100 at both ends of the switch and Edge router.

We have 100MB link from ISP.

Int gi0/0 from edge router connects to ISP Router.

Speed on interface gi 0/0  of Router is hardcoded to 100

Need to know is there any benefit of changing speed to 1000 on switch and edge router interface gi0/1?

ISP link is 100MB so that means our internet speed can not go more than 100 MB.

Regards

MAhesh.

[Drew Browning · Accepted solution]

Why wouldn't you just let your switch and router auto-negotiate and only hardcode the edge to provider side? 

[mahesh18]

Hi,

This is existing setup and i was told by  previous network admin that since our Internet speed is limited to 100 MB the port should be set to 100.

Router and switch if i set to auto negotiate will negotiate to 1000 as both interfaces are gig.

But my concern is that will changing to auto make any difference in speed?

Regards

Mahesh

[Rasika Nayanajith · Accepted solution]

Hi Mahesh,

It will not make any diffrence to your internet (since ISP limited to 100Mbps).

It is best practice to leave port config to auto negotiate. Within your network (link between your edge router & switch) make it auto negotiation (speed auto, duplex auto) &  let it to negotiate 1Gbps full duplex.

If you hardcoded, some times I have seen some wierd behaviour in connectivity, specially since a power outage of a device.

HTH

Rasika

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[Drew Browning · Accepted solution]

Just config your switch and router to auto-negotiate with each other and hardcode the edge to provider.  This way you are better utilizing the speed capacity of your internal network.

[Joseph W. Doherty · Accepted solution]

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Posting

This is an "it depends" answer.

Many of the smaller ISR routers, although the have gig Ethernet interfaces, can struggle with gig bursts.  Setting the LAN side to 100 Mbps slows how fast a burst might be received, which can avoid overrunning your router.

On the other hand, if you slow the LAN facing interface to 100 Mbps, traffic shouldn't enqueue on the edge router's Internet facing interface, it may enqueue on the switch interface to the router.  The problem with that, the router, if a router and not a L3 switch, probably has a richer QoS feature set than the switch, which you may want to take advantage of.

I would recommend running the LAN interface at gig, and monitoring CPU usage and interface drops.

[mahesh18]

Many thanks to everyone for answering my post.

Best regards

Mahesh