Hi all, hope all is well, I have a question, ig i change the speed and bandwidth on a 1 gigabit interface to speed of 100 and bandwidth 100, will this interface be equivalent to a Fast ethernet interface (100mb)?
Thank you for the help in advance.
Hello Sidney
The speed command will change the actual operational bandwidth of the interface. For Ethernet interfaces, the only options you have for speed are 10 Mbps, 100 Mbps, 1000 Mbps, and for interfaces capable of higher speeds, you may also have 10Gbps, 25Gbps, 40Gbps, 100Gbps, and so on. So the speed command will only allow you to configure specific speeds, those that the interface is capable of operating at.
The bandwidth command is different. Changing this value will not affect the actual bandwidth of the interface. It actually acts as a label on the interface and is used to determine the cost and metric of routes when using routing protocols such as EIGRP or OSPF. You are able to configure any bandwidth value with the given range of the command. This value should only be changed if you want to influence routing performed by a routing protocol, in some manner.
I hope this has been helpful!
Laz
1 Like
Hi @lagapidis, thank you for your response, this answers and clarifies my question. Thank you.
1 Like
We have applied for 10 mb mpls link, provider has hard coded the negotiation and set to speed 10 full duplex, so at our end also we need to hard code to 10 full duplex. is it correct ? Ideally in my understanding, Speed should be 100 with full duplex. Provider can cap the speed at PE end with rate limit etc. please suggest if this is correct to set speed 10 and duplex full, will it impact when it come to production ? or should get it changed to speed 100 with full deuplex ? Expecting quick reply on this, thanks for your clarification as always.
Hello Ravi
It all depends on what layer 2 technology the service provider is delivering to your premises, and what they have configured on their end.
Is it an Ethernet connection, and theyâre running MPLS over that? If so, and if they have configured 10 Mbps on their end, then yes, you must do the same on your end. Thatâs simply how Ethernet works. You would apply this independent of what technology is running on top of that. If there is a speed mismatch, the link will simply not come up. The speed must match on both ends regardless of all other parameters.
Now if the provider is delivering the 10 Mbps in a different manner, say using rate limiting, as you mention, then the speed on the interface has nothing to do with that. The provider may be giving you a GigabitEthernet interface, and rate limit it to 10Mbps, the result would be the same.
So on your end, you should set the speed and duplex to whatever is configured on the provider end. Otherwise, the link will not function.
I hope this has been helpful!
Laz
@lagapidis thanks for your explanations. I have a 100mbps link and on one side it is hard coded for 100/Full , on the other side it is set to negotiation auto and the speed duplex setting of the GE interface gets negotiated to 1000/Full .
We are seeing alot of output drops on this link, would the pseed mismatch explain that?
The side on which it is set to auto is a ISR4431 and it doesnât allow me to hardcode the speed to 100/Full ie it said âinvalidâ when I try to enter the speed/duplex command in the interface configuration mode.
Hello Jacqueline
It is likely that the speed mismatch is causing the output drops on the link. It is of utmost importance that the speed and duplex settings be the same on both ends of the link, whether negotiated or hardwired. Otherwise you will have undesirable and unpredictable results similar to what you are seeing.
After doing some reaserch, I have learned that the ISR4431 is somewhat sensitive to the order with which such commands are inputted. Based on this Cisco Community forum thread, if you want to manually configure the speed and dupliex, the interface must be up, and then you ensure that it is initially set to ânegotiation autoâ, then you can set it to âno negotiation autoâ and finally set the speed to your desired setting.
Try this out and let us know how you get along!
I hope this has been helpful!
Laz
Hi @lagapidis ,
Thank you so much for taking the time. It appears the above solution from the cisco community forum didnât help. In fact despite following the process, it still does not take the speed/duplex command.
Weâre trying to troubleshoot severe lag and slowness experienced by our users at the remote end on the internal network. This is the only remote site experiencing this issue. The speed on the internet works fine and internet browsing and downloads works as expected.
We took some packet captures on the wan tunnel interfaces recently(ipsec), we observed a few retransmissions but a more alarming thing was the very small window sizes most of them between 1000-2000 and few going upto 10000, most of the packets were arriving out of order in both directions. We saw nothing higher than that.
Would it be advisable at this stage to ask the wan service provider to hardcode the speed duplex settings to a 100 on their end?
Hello Jacqueline
Based on the issues youâve described, it seems like the problem could be related to your WAN link rather than your internal network, especially if other remote sites are not experiencing the same issue. The small window sizes and out-of-order packets could be indicative of a congested or unstable WAN link.
Such issues are hard to diagnose, and your packet capture does begin to shed some light on the issue. You could ask the ISP to hardcode the speed and duplex settings to see if that will make a difference. Ultimately, you will have to pinpoint the location in the network that is causing the problems. This can be done by taking packet captures at various points, on the customer end as well as on your end. If it is indeed over the WAN link that the problem arise, you can then work with your ISP to resolve the issues. Let us know how you get along and if we can be of further helpâŚ
I hope this has been helpful!
Laz