Cisco Catalyst 3550

Hi Chris you seems to be really accurate in the Vlan field, I cannot wait to ready your paper, Iam currently working on the security aspect of a Vlan architecture, I might need your help, I have 3550 L2 switches and a core 2948 L3 switch, trunk hsa been created btw the switches, and bridge created. As 2948 L3 does not allow access list, I am looking for informations about vlan acces list, have you implement it already ?. Thx

If you're doing an analysis of VLAN security, make sure you look into VLAN jumping. A lot of people use VLANs as a layer of security to provide an isolation network. Unfortunately, it is possible to get packets to 'jump' VLANs if you have a little bit of information.

Hi sahir , well I have dont my layer 2 risk analysis, I found some really good information about, vlan hoopingm mac attack , arp , trunk etc, but still, I found this amazing thing on network that I am studying, there is vlans, a layer 3 to route the traffic between vlan, but here the problem everyone can access everywhere :shock: , so the vlans are useless, I have been readyin gand ready the conf file but I am still confuse with the port channel and bridge group.

Hi Chris,

Is it possible to give a rough sketch of your babies connected. i.e. you had told you work with 12 Cat3550, if it is possible, with all the vlan details and the ip addressing scheme, and which of these Cat3550 are acting as Layer 3 switches and which are Layer 2 and also how have you connected this switch fabric to the external network (through a router).

Waiting for an early reply with the sketch.

Regards

huliyar,

I would love to post here my diagrams containing all the details, but I'm afraid it won't be possible due to security reasons, something I'm sure you understand. As the company's network Engineer, I am unable to disclose any such information!

What I can tell you without compromising critical information, is that our network consists of 14 (I just counted them) 3550 Catalyst switches, Call Managers (Cisco VoIP), Cisco Voice Gateways and a variety of other Cisco technologies.

All the above connect via redundant fiber optic Ethernet Gigabit links to our two main 3550 Catalyst switches which also perform the InterVLAN routing between all available VLANs. These two main switches have also been configured with active standby, so in case one fails, the other takes over automatically.

When the VLAN topic is published, I assure you that all your questions will be covered. The examples I will be using to help illustrate how VLANs work and are setup, will be taken from real live networks, ensuring their accuracy and relevence.

For those interested, I am actually half way through the topic, having covered 7 out of the 14-15 pages. These 7 pages also include at least 25 diagrams!

With the VLAN topic, we are also introducing our next generation graphics/diagrams which are simply awesome, but require a considerable more amount of time to produce, which is one of the main reasons the topic is moving slowly. Currently, I am expecting to have it complete before the end of the month.

Cheers,

HI,

Im just waiting for the VLAN subject that you are going to publish.
With the description that you have given about your network I get the feeling that it might resemble something like the Figure 1.2 in the following link.

www.cisco.com/en/US/products/hw/switches...44.html#xtocid225061

If yes then I feel that im also going in the right way understanding how Layer 3 switches work and where it is placed in the enterprise networks.

Bye.