Problem in the Vlan numberning

[prashirsha1]

Hello,

When i am creating any vlan id it is having drop in end to end connectivity. After changing the vlan id the problem resolved. I have talked to the media team the said that for both vlans the path is same. Does the vlan id can create problem.

For example if i am creating any vlan id ie.2992 it is having drops in end to end connectivity while in vlan id ie.2995 no drops occur. media is same for both vlan.

[Peter Paluch]

Hi,

This discussion would be more suited for Network Infrastructure - LAN Routing&Switching. Please consider moving it there by clicking at the Edit button at the top of the screen.

You are talking about drops in end to end community - what does it mean exactly? Is it a complete loss of connectivity, or do you mean packet loss every now and then?

A complete loss of connectivity is most often caused by either not having this VLAN allowed on appropriate trunks, or by forgetting to create this VLAN on some intermediate switch in the path.

Packet losses within a particular VLAN indicate either a physical layer problem causing errors in frame transmission (duplex mismatches, cabling faults, ...), or a capacity issue with overloaded links or even entire switches.

No packet losses in VLAN 2995 and packet losses in VLAN 2992 would be more indicative of a capacity issue. However, you should really check if the spanning tree in these both VLANs is the same and whether they are truly using exactly the same links throughout the whole switched network. Does the VLAN 2995 use any QoS mechanisms?

In addition, if you are running Rapid PVST or MST, are your inter-switch links recognized as point-to-point links by the protocol, and are the ports toward end hosts configured as PortFast (that is, edge) ports? Failure to do so could cause intermittent connectivity when a topology changes.

Best regards,
Peter

[prashirsha1]

Hi Peter,

Thanks, i will talk to media team regarding this. just need a little bit more info, suppose i am taking vlan id with 2992 it is having drops but when i simply changed it to 2995 . no drops occur. path is same . so does by changingthe simply id value make this happen or it is just a coincidence.

[Peter Paluch · Accepted solution]

Hello,

The VLAN ID alone has absolutely no impact or influence on the packet drops. There must be something else configured that causes the handling of traffic in VLAN 2992 to be different than in VLAN 2995.

Best regards,
Peter 

[Archit Saxena]

a very noob doubt sir i just completed my ccna and there we were told that vlan id is between 2 through 1001so how come the number 2992

[Peter Paluch]

Hi Archit,

The VLAN range you are talking about is a so-called normal VLAN range, and it goes from 1 through 1005. This was the first range of VLANs implemented by Cisco in times when there was no open inter-vendor standard on how VLANs should be implemented and operated between switches. Later, when IEEE came with its 802.1Q standard that defined the VLAN range to be 0 through 4095 (numbers 0 and 4095 are reserved for special use). Cisco had to extend their supported VLAN range from 1006 up to 4094, and this is what they call the extended VLAN range.

So VLANs are in fact numbered between 1 and 4094, inclusive. However, Cisco switches - because of historical reasons - split this range into two parts: the normal-range VLANs (1-1005) and extended-range VLANs (1006-4094). There may be some slight configuration required on Cisco switches before they allow you to use extended-range VLANs (and that would be either setting the VTP mode to transparent/off, or using VTP version 3 that supports extended range VLANs).

Best regards,
Peter

[rosaho]

This discussion has been reposted from Additional Communities to the LAN, Switching and Routing community.