CAT 3560

[anitachoi3]

Hi,

The router 3660 would be phased out. There are about 8 physical interfaces to be configured. Grateful if expert would advise on following:

1. CAT 3560V2 could be acted as router if the IOS is IP base and "IP routing" is enabled. Does it support the physical "layer 2" port to be the  physical "layer 3" interface? (e.g. there are 24 ports of 3560v2 switch, it becomes to 24 interfaces of "layer 3" router port)  

2. If the answer of Q1 is "yes", appreciate that your would advise on the sample configuration (or web link) of the setup

3. If the answer of Q1 is "No", VLAN configuration is one and only one solution, isn't it?

rdgs

[Pronoy Dasgupta · Accepted solution]

Hey Anita,

A couple of things here, with the IP Base image, you would only get limited routing functionality, meaning, static routing and RIP. No other advanced protocols can be configured with the IP Base image.

Yes you convert all the ports to layer 3 ports. They start off as layer 2 by default.All that needs to be done, is to configure "no switchport" command at the interfaces which you are planning to use as layer 3.

Thanks

Pronoy

[Ganesh Hariharan · Accepted solution]

Hi,
The
router 3660 would be phased out. There are about 8 physical interfaces
to be configured. Grateful if expert would advise on following:
1.
CAT 3560V2 could be acted as router if the IOS is IP base and "IP
routing" is enabled. Does it support the physical "layer 2" port to be
the  physical "layer 3" interface? (e.g. there are 24 ports of 3560v2
switch, it becomes to 24 interfaces of "layer 3" router port)   
2. If the answer of Q1 is "yes", appreciate that your would advise on the sample configuration (or web link) of the setup
3. If the answer of Q1 is "No", VLAN configuration is one and only one solution, isn't it?
rdgs

Hi,

The IP Base feature set includes advanced quality of service (QoS), rate limiting, access control lists (ACLs), and basic static and Routing Information Protocol (RIP) functions. Dynamic IP routing protocols (Open Shortest Path First (OSPF), BGPv4, Enhanced Interior Gateway Routing Protocol (EIGRP)) are available only on the IP services image and you can configure all the 24 ports into L3 ports and as pronoy said by default these ports are in L2 mode only.

Check out the below link for sample configuration of intervlan routing 3560 switches.

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a008015f17a.shtml

Hope to Help !!

Remember to rate the helpful post

Ganesh.H

[anitachoi3]

Hi,

One more question.

If the all ports of CAT switch can be configured as layer 3 router ports, why do we need router 28xx to 39xx serial router? According to $ per port, router is very expensive. The CAT switch can provide the fast switching than router. Is it correct?

rdgs

[Jon Marshall]

anitachoi3 wrote:
Hi,
One more question.
If the all ports of CAT switch can be configured as layer 3 router ports, why do we need router 28xx to 39xx serial router? According to $ per port, router is very expensive. The CAT switch can provide the fast switching than router. Is it correct?
rdgs

Yes, a 3560 supports L3 switching ie. routing in hardware so against a comparable (in price) router the switch will always provide better peformance. But routers offer far more functionality than switches -

1) NAT - only the 6500 switch supports NAT

2) QOS - routers have a much more fully featured QOS toolset ie. shaping is not supported on most switches

3) Interface types - 3560 switch only supports ethernet interfaces

etc...

If a 3560 switch has all the features you need to support then it is a viable alternative but there is nothing worse than replacing a router only to find out that the switch you have just purchased doesn't support something your network relies on

Jon

[anitachoi3]

Thank you very much

[Ganesh Hariharan]

Hi,
One more question.
If
the all ports of CAT switch can be configured as layer 3 router ports,
why do we need router 28xx to 39xx serial router? According to $ per
port, router is very expensive. The CAT switch can provide the fast
switching than router. Is it correct?
rdgs

Hi,

Just to add on Jon's Comment as he as explained very well the difference between L3 and router,Let me provide some more information in brief between the two devices.

Layer 3 switches are faster than routers, but they usually lack some of the advanced functionalities of routers. router analyzes the Layer 3 destination address of every packet, and devises the best next hop for it. This process takes time, and hence every packet encounters some delay because of this.

In a Layer 3 switch, on the other hand, whenever a routing table searches for any specific destination, a cache entry is made in a fast memory. This cache entry contains the source-destination pair and next hop address. Once this cache entry is in place, the next packet with the same source and destination pair does not have to go through the entire process of searching the routing table. Next hop information is directly picked up from the cache. That's why it is called route once switch many

router has some advanced routing functionality, which Layer 3 switches lack which Jon has already stated like Nat,qos etc. Layer 3 switches are primarily used in the LAN environment, where you need routing. Routers are used in the WAN environment.

Hope to Help !!

Ganesh.H

[anitachoi3]

Thank you very much

[Leo Laohoo]

You want to replace a c3660 router with a Catalyst 3560 MLS.  Sounds good.

1.  What ethernet connections do you have on the c3660 ?
2.  Are you doing any NAT on the c3660 ?
3.  What WAN links does the c3660 have?