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tunnel interfaces

How many virtual interfaces can you have on one physical interface?

3 REPLIES
Hall of Fame Super Silver

Re: tunnel interfaces

Brent

As a general question I believe that there is not a limit on the number of virtual interfaces on one physical interface, other than the limit on the number of virtual interfaces, which is a function of the number of IDBs and that varies from platform to platform (and sometimes varies by version of IOS). Note that for certain media there may be some limits on the number of virtual interfaces. For example if the physical interface is a serial interface with Frame Relay encapsulation there is a limit on the number of PVCs which would establish a limit on the number of subinterfaces. Or if the interface were a FastEthernet connected to a switch and doing trunking there might be a limit on the number of VLANs supported on that particular switch which would establish a limit on the number of subinterfaces.

HTH

Rick

Cisco Employee

Re: tunnel interfaces

Rick,

Just to supplement your comment on the number of IDB supported on a given platform (and IOS SW release), you can use the "show idb" command to see that limit.

r1#show idb

Maximum number of Software IDBs 1024. In use 10.

HWIDBs SWIDBs

Active 6 7

Inactive 3 3

Total IDBs 9 10

Size each (bytes) 4328 1376

Total bytes 38952 13760

Type SIdx Idx St,O,Sh Interface Name (subblocks)

---------------------------------------------------

H 1 1 U,I,R Ethernet0/0 (HW SB CDP(6), MAC ADDR(2), Ether(1))

H 2 2 A,I,R Ethernet1/0 (HW SB CDP(6), MAC ADDR(2), Ether(1))

H 3 3 A,I,R Serial2/0 (HW SB CDP(6), Frame relay(5), Serial(3))

H 4 4 A,I,R Serial3/0 (HW SB CDP(6), Serial(3))

H 5 8 U,D,R Auto-Template1 (HW TUN_TEMPLATE(4))

H 6 7 U,R,R Loopback0

S 1 2 U Ethernet0/0 (SW CDP(3), IPv6(10001), LLC2(1))

S 2 3 U Ethernet1/0 (SW CDP(3), IPv6(10001), LLC2(1))

S 3 4 U Serial2/0 (RSVP(5), SW FR SUB(2), LLC2(1))

S 4 10 D Serial2/0.1 (RSVP(5), Tagswitch(4), SW CDP(3), LLC2(1), SW FR SUB(2))

S 5 5 U Serial3/0 (SW CDP(3), LLC2(1))

S 6 9 U Auto-Template1 (LLC2(1))

S 7 8 U Loopback0 (LLC2(1))

Key: SIdx=Sort Index, Idx=hw_if_index or if_number

St=Current State, O=Old State, Sh=Shadow State

A=Admindown, D=Down, G=Going Down, I=Init

R=Reset, T=Testing, U=Up, X=Deleted

r1#

Regards

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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