Vlan Lab

Dec 14, 2005 2 Replies
A

I have a pair of 1900EN switchs. I am trying to learn about VLANs and how they work....



I have connected the swiches via a crossover cable on port 26 or B on both switches.



I have also setup SPAN on one switch (port 25) and monitoring port 26 trunk port. I created 2 vlans, 1 and 2. I put a one pc in VLAN 2 on switch1 and put another pc in VLAN 2 on switch2.



I have setup a ping -t goign between the PC's



I can see that the Trunking is working because I am getting a repsonce and if I disbale the trunking the pings fail. So thats good!



My problem is that I am trying to sniff the trunking ports and look at the packets and look to find the ISL header information. I am getting alot of STP traffic and the ICMP traffic...but I can't see anything to do with ISL?



Is this normal? What am I doing wrong?



I know this is abit more than CCNA stuff...but I am just a geek I guess =)


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M

snipped-for-privacy@one.com schrieb:

Cisco SPAN Configuration Guidelines:

[...]

- A trunk port can be a source port or a destination port. When a destination port is a trunk port, outgoing packets through the SPAN port carry the encapsulation headers configured by the user?either Inter-Switch Link (ISL) or IEEE 802.1Q. If no encapsulation type is defined, the packets are sent in native form. [...]

So the problem could possibly be that the frames which are mirrored to port 25 are not sent in encapsulated form anymore.

Martin

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A

Humm ok, I will give that a go. the other thing I thought about is maybe use a hub between the trunk...

But try that first..

Cheers

snipped-for-privacy@one.com schrieb:

Cisco SPAN Configuration Guidelines:

[...]

- A trunk port can be a source port or a destination port. When a destination port is a trunk port, outgoing packets through the SPAN port carry the encapsulation headers configured by the user?either Inter-Switch Link (ISL) or IEEE 802.1Q. If no encapsulation type is defined, the packets are sent in native form. [...]

So the problem could possibly be that the frames which are mirrored to port 25 are not sent in encapsulated form anymore.

Martin

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