Multi-layer Switches

[Docklands]

How can you be certain that a multi-layer switch will act as a router on a stick to allow routing between vlans on a trunk?

[Georg Pauwen]

If you have configured a trunk to the switch/router that carries the relevant VLANs, and if routing is enabled on the router/switch, inter-VLAN traffic will be routed.

Do you have a specific problem ?

[Docklands]

Hello

We had some doubts about the Ethernet modules for the new ISR 4000 series.

The WAN modules specifically state they will terminate vlan trunks and route but we could not find confirmation for the SM-X Ethernet 16-48 ports switches.

Thanks

[Georg Pauwen · Accepted solution]

Hello,

it depends on which platform you are using the module in. For e.g. the 2900 and 3900 ISR series, the following applies:

Cisco SM-X Layer 2/3 ESM can directly communicate with any module connected to the backplane switch of the router bypassing the router host CPU, thus, increasing the CPU performance and reducing the CPU processing. The additional GE connection with the router backplane switch designated as GigabitEthernet X/1 port where X is the slot number. This port can be access port or a trunk port.

[Docklands]

Another question concerning the ISR 4000 series. There seems to be some issue with it running HSRP as it cannot use two mac addresses, although some sites suggest there is a workaround. Do you know if the workaround has limitations?

[Georg Pauwen]

Hello,

those restrictions apparently have been removed by upgrading your IOS:

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp_fhrp/configuration/12-4t/fhp-12-4t-book/fhp-hsrp.html#GUID-FD4B280C-83C0-4F66-ABB4-75D012ACB511

[Docklands]

The way it reads only applies to one of the restrictions:

The same HSRP group number or HSRP MAC address cannot be configured on different subinterfaces of the same major interface.

The rest would appear to still be applicable

[Georg Pauwen]

Hello,

you are right...I missed that.

If you do a 'show interfaces' is your Ethernet hardware actually Lance? I think Lance is an older hardware, and at the very least the second generation ISR routers do not use it anymore.

[Docklands]

Hi,

Thank you for your help.

We haven't purchased the ISR4000 as yet. I was just running some checks on the 4000 after our original choice (2900) went end-of-life and found the article on the Cisco site.

The article is dated 2009 so there is a good possibilty that the Lance hardware is not used anymore.

Is there a way of finding out for sure as we intend to use the 4000 for a project that is getting behind schedule.

Thanks

[Georg Pauwen]

Here is the output of a 'show interfaces' from the 4331 ISR:

GigabitEthernet0/0/0 is administratively down, line protocol is down
Hardware is ISR4331-3x1GE, address is 006b.f10a.8890 (bia 006b.f10a.8890)
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,

As far as I know, Lance has not been around for quite a while in the new routers.