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New Member

Catalyst 3560G's

I am relatively new to the whole Cisco world of networking (not so new to networking). We have recently moved over from a 3 Com solution to almost a full pure Cisco based network (ADSL router is netgear).

Currently our network is setup as

Netgear ADSL Router

Pix 515E

Catalyst 3560G-48PS x 1

Catalyst 3560G-48TS x 2

I have configured the pix and catalysts from scratch and got them working (big improvement over what we had). Very quickly I learnt about configuring the physical ports as our devices couldn't negotiate links quickly enough for DHCP (spanning-tree port-fast) and generally configured the devices all ok. I have set the switches up in a mesh format for now with the Switch Macro to trunk 2 ports between each switch.

Our Catalyst switches are all just sat ticking over sunning themselves not really working hard. I know we can get bigger gains from these devices and have a few questions that hopefully people can assist with. I have tried Google and I am going to be working towards CCNA as soon as the new books come out but I am struggling to get the answers.

1) Are there any performance gains to be had from Clustering the switches? I know about the admin gains in that its one device etc but with only 3 switches admin is not too much of a heart-ache.

2) Jumbo Frames. I know that to get the most bandwidth used by a Gig network Jumbo frames should be enabled otherwise you hit the limit of the standard MTU. In the Cisco documentation it states

Quote:

If Gigabit Ethernet interfaces are configured to accept frames greater than the 10/100 interfaces, jumbo frames ingressing on a Gigabit Ethernet interface and egressing on a 10/100 interface are dropped.

Does the above mean that if jumbo frames are enabled then gigabit devices cannot talk to 10/100 devices (printers for example)? From what I know of networking as part of the initial connection between two devices they negotiate an MTU to use so the gig and fast ethernet devices should talk happily and work as normal.

If anybody can assist with the above it would be a great help.

Thanks

Mark

1 ACCEPTED SOLUTION

Accepted Solutions
Bronze

Re: Catalyst 3560G's

In the 3560 you can enable jumbo support globally on the entire switch. This will not prevent any communication and will only allow MTU greater than 1500 if the devices /can/ communicate with jumbos. I have it on my 3560s and have printers and big servers also.

2 REPLIES
Bronze

Re: Catalyst 3560G's

In the 3560 you can enable jumbo support globally on the entire switch. This will not prevent any communication and will only allow MTU greater than 1500 if the devices /can/ communicate with jumbos. I have it on my 3560s and have printers and big servers also.

New Member

Re: Catalyst 3560G's

Just the answer I was looking for thank you. The Cisco Documentation wasn't 100% clear. I understood from networking that the MTU was negotiated at the start of comms so it shouldnt be a problem but needed to check.

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