2821 Layer 3 Interfaces

Answered Question
Jan 5th, 2010

Hi,

I have gone over much of the documentation on the 2821. It primarily points out that it can only support a single 2 Port Layer 3 HWIC card. However that combined with the onboard interfaces will only give me a total of 4 physical routed interfaces.

What are my options if I require 6 physical routed interfaces in terms of physical card specifications?

Thank you for all you help

I have this problem too.
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Correct Answer by Jon Marshall about 7 years 3 weeks ago

winstonritson wrote:

Hi,

Thank you.

So John I am correct in my understanding that 4 interfaces is the physical maximum fro routed interfaces?

Thank you with the ideas for the 38xx but vlans won't work as some of the interfaces would run routing protocols.

Yes, for the 2821 4 physical routed interfaces is the limit.

You can still peer with a vlan interface rather than a physical interface although this is not on the actual physical interface as you say.

Jon

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Jon Marshall Tue, 01/05/2010 - 06:16

winstonritson wrote:

Hi,

I have gone over much of the documentation on the 2821. It primarily points out that it can only support a single 2 Port Layer 3 HWIC card. However that combined with the onboard interfaces will only give me a total of 4 physical routed interfaces.

What are my options if I require 6 physical routed interfaces in terms of physical card specifications?

Thank you for all you help

If you really need routed physical interfaces then to get 6 you need to be looking at a 38xx or 39xx router, see this attached data sheet -

http://www.cisco.com/en/US/prod/collateral/routers/ps5854/product_data_sheet0900aecd80581fe6_ps5855_Products_Data_Sheet.html

If however you just need L3 interfaces then don't forget about the ethernet switch modules which allow the creation of L3 vlan interfaces.

Jon

winstonritson Tue, 01/05/2010 - 06:58

Hi,

Thank you.

So John I am correct in my understanding that 4 interfaces is the physical maximum fro routed interfaces?

Thank you with the ideas for the 38xx but vlans won't work as some of the interfaces would run routing protocols.

Correct Answer
Jon Marshall Tue, 01/05/2010 - 07:21

winstonritson wrote:

Hi,

Thank you.

So John I am correct in my understanding that 4 interfaces is the physical maximum fro routed interfaces?

Thank you with the ideas for the 38xx but vlans won't work as some of the interfaces would run routing protocols.

Yes, for the 2821 4 physical routed interfaces is the limit.

You can still peer with a vlan interface rather than a physical interface although this is not on the actual physical interface as you say.

Jon

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