Unanswered Question
Jan 8th, 2009

Do 6500 series supervisor engines have a model that can create SVIs with 10G bandwidth?

We are uplinking data center access switches to the distribution switches using 10G transceivers but the we end up with 1G routing speed between the SVI vlans created by the SUP720-3B supervisors.



I have this problem too.
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Roberto Salazar Thu, 01/08/2009 - 10:28

The SVI or interface vlan is a logical interface. It will always say 1000 mbps under show interface but remember it's not a physical interface. The bandwidth is determine by the rate of the physical interface. Also, the transfer rate between hosts is determined by many factors not only the ports they are connected to or the port that switches connect with each other. for example, you have a host connected to a gig port doing an ftp to a server connected to another gig port but you have a T1 somewhere in between those two devices, you can't expect the transfer rate between the two host separated by a T1 rate to do 1 gig.

Hope that clears it up.

jdw28 Thu, 01/08/2009 - 10:38

I understand many factors affect the actual throughput between two transmitting hosts.

However, I would like to know if the SVI interface can show 10G bandwidth with a different supervisor engine, similar to following 10G switch port:

hssl-b-6509E-b#show int te1/1

TenGigabitEthernet1/1 is up, line protocol is up (connected)

Hardware is C6k 10000Mb 802.3, address is 001d.70f1.7108 (bia 001d.70f1.7108)

MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec

I can configure the switch port as a routed port by placing an IP address on it, thus getting a routed 10G port, but SVIs are more practical in our environment.



Jon Marshall Thu, 01/08/2009 - 10:46


What Roberto is saying is that a routed port showing 10Gbps means 10Gbps throughput. An SVI showing 1Gbps does not mean 1Gbps throughput. It is a virtual interface and the actual thoughput is based on the physical interface throughput plus switch fabric etc. on the 6500.

If you are asking if there is an IOS that will show 10Gbps under the SVI, which would be purely cosmetic, then i don't know.


jdw28 Thu, 01/08/2009 - 11:02

Hmm, we are using EIGRP. Isn't true interface bandwidth, configured or default, and delay are the two main factors determining the path to a destination? This means the default SVI bandwidth number matters. I can easily change the bandwidth statement on the SVIs to 10G but I prefer to let the IOS to determine it.

Anyway, thanks for the replies.


Giuseppe Larosa Thu, 01/08/2009 - 11:11

Hello Jim,

we had the same problem in the past with hybrid mode and GE ports and OSPF auto-reference not updating the cost of SVI.

An SVI is a virtual host connected to layer2 broadcast domain.

How could trace the routing protocol that devicea is out a 10GE port and deviceb is out a 1GE port both members of the same vlan ?

So you should adjust manually cost parameters to reflect your topology.

Hope to help


Jon Marshall Thu, 01/08/2009 - 11:15


I don't believe EIGRP supports interfaces with a bandwidth of more than 1Gbps anyway ie. 10Gbps and 1Gbps will both be seen the same by EIGRP. I believe Cisco are looking into this.


Roberto Salazar Thu, 01/08/2009 - 10:47


the SVI will always show 1000000 Kbit bandwidth this is because, on cat6K architecture, the pinnacle port to the RP is a 1 gig port. but that does not mean traffic is limited to 1 gig and it also does not guarantee a gig traffic rate. If you want to ensure a ten gig traffic end to end then you will have to make sure that ten gig is available end to end. My point is even if you make the ten gig interface a routed port, it will not really give you a ten gig end to end unless your network is ten gig end to end, from host to host port and everything in between.

jdw28 Thu, 01/08/2009 - 11:08

I guess I should look into Nexuss 7000 platform for higher bandwidth support. I agree with you 10G is achievable only if 10G is implemented host to host.

Thanks again.



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