c2821 Maximum Number of Vlans encap. dot1q

Answered Question
Jan 15th, 2009

How many Vlans encapsulation dot1q does support an c2821 with 2 Gigabit Ethernet interfaces?

Thanks.

I have this problem too.
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Correct Answer by Giuseppe Larosa about 7 years 10 months ago

Hello Mariano,

in a router each Vlan subif takes a row in the IDB = interface descriptor block.

the total of physical and logical interfaces on your router cannot be higher then the IDB size.

This number is dependent on platform and IOS version.

on a c2821 the IDB can be 512

I didn't find the number so you should be able to implement several subinterfaces on your router.

2821

900

see

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml#idb_limits

I shouldn't go behind 20 subinterfaces per GE there are other factors to be considered like the size of the NIC MAC packet filter.

Hope to help

Giuseppe

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Correct Answer
Giuseppe Larosa Thu, 01/15/2009 - 13:28

Hello Mariano,

in a router each Vlan subif takes a row in the IDB = interface descriptor block.

the total of physical and logical interfaces on your router cannot be higher then the IDB size.

This number is dependent on platform and IOS version.

on a c2821 the IDB can be 512

I didn't find the number so you should be able to implement several subinterfaces on your router.

2821

900

see

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml#idb_limits

I shouldn't go behind 20 subinterfaces per GE there are other factors to be considered like the size of the NIC MAC packet filter.

Hope to help

Giuseppe

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