Extending switch Trunk with port-channel

[timothylau]

Hello,

I have two c3560cx-12TC-s, connecting through the two fiber SFP modules to each other. It is set with trunk and port-channel on these two ports. (i.e. gi0/15 and gi0/16). The ports are almost in full capacity (only 1 port left). So I am thinking is that possible to extend the capacity by adding another c3560cx into this setup? And how? Using the same trunk setup and with port-channel? 

As of now, we have a plain spare 3850-48sx in the storage. I am thinking if we can re-use in this situation.

[MHM Cisco World]

add another SW will not solve capacity issue it will help you to in case of one SW is Down. 
to solve the capacity why you not add more port member to PO ?

[timothylau]

oops sorry, I think I make it wrongly. What I mean the ports are almost full, there is only one port left not being used.

[MHM Cisco World]

even if we add one as stack the triangle will not help us here, 
we need two additional SW 
one stack with Access SW and other stack with Core SW.
If we use only left port to connect to new SW that make traffic congestion in this only port. 

[timothylau]

Yes. Indeed, this is just one part of the network. The switches are placed in the DMZ. I wonder if we could make it simply as possible. 

I saw the most ports it has in 3560CX is 12 ports. Is that reasonable to replace these two with another switch with 24ports? Any suggestions?

Cheers 

[MHM Cisco World]

24 ports or more C9000 can support up to 48 ports. 

[timothylau]

we have a direction to go for C9200L 24 ports, either 1G or 10G fixed uplinks. 

But there is something I would like to confirm, if we stacked the two 9200L switches, it becomes one managed switch. Is that still good for having HA for the devices that connected to? 

Back to the top post, we have two c3560cx switches, we have two firewalls connected on each switch, also each switch connected with the ISP router, they don't setup with any Port-channel.

[Reza Sharifi]

But there is something I would like to confirm, if we stacked the two 9200L switches, it becomes one managed switch. Is that still good for having HA for the devices that connected to? 

That is correct. When you stack multiple switches together, they logically become one switch, and you are managing the whole stack with one management IP address. Also, stacking will provide full HA, as long as the end devices are connected to both physical switches.

Back to the top post, we have two c3560cx switches, we have two firewalls connected on each switch, also each switch connected with the ISP router, they don't setup with any Port-channel.

Now, that you are replacing them with a stack of 9200L switches, all you need to do is to connect the firewalls to both switches. Also, depending on the firewall vendor, there is usually no need for Portchannel specially if the firewalls are in HA mode.

As for ISP connectivity, there is no need for Portchannle. If you have redundant providers connect each to one switch. If this is for Internet connectivity, usually they hand-off a layer-3 connection to you, and you can use a /30 for each provider.

HTH

[Joseph W. Doherty]

BTW, port channels, generally, can only nr between a pair of devices, you cannot have the same port channel links going to different devices (an exception is stacked switches, where, logically, it's just a single switch).

In your proposed designs, you can interconnect the switches, in the triangle topology, but without using port-channel.  You will need something like STP, for L2, or make these L3 links, as all your switches, I believe, are L3 capable.

BTW, you're not limited to just using your SFP ports for interconnecting your switches.

[timothylau]

Will go ahead for the stack switches. If in worst case, just get rid of the stack connections, then use the SFP for the port-channels setup. Try to minimise the risk if in the future when switching over to the new switches.

Thanks all.

Cheers.