Solved: Bandwidth and Eigrp

jogillis · ‎06-05-2008

If I change the bandwidth statement on an interface (serial subinterface), do I have to bounce the interface/subinterface for eigrp to start using the new value for route calculations?

Thanks

Edison Ortiz · ‎06-05-2008

You need to change the bandwidth on the interface running EIGRP.

If the subinterface had an BVI associated to it, it means the subinterface represented the Layer2 connection while the BVI represented the Layer3 instance. EIGRP runs on interfaces with Layer3 (IP) information.

HTH,

__

Edison.

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Edison Ortiz · ‎06-05-2008

No, you don't.

__

Edison.

jogillis · ‎06-05-2008

Then I guess I have something else going on here. I removed the bandwidth statement from the interface. A "show interface" shows the new bandwidth (the default), but if you look at the "show ip eigrp topo" for routes, these reflect the old bandwidth (BW) statement.

Edison Ortiz · ‎06-05-2008

Hmm, let me pull up my lab...

Rack1R2#sh ip eigrp topology 192.168.1.1 255.255.255.255

IP-EIGRP (AS 1): Topology entry for 192.168.1.1/32

State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2297856

Routing Descriptor Blocks:

192.168.12.1 (Serial1/0.1), from 192.168.12.1, Send flag is 0x0

Composite metric is (2297856/128256), Route is Internal

Vector metric:

Minimum bandwidth is 1544 Kbit

Total delay is 25000 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 1

__________

Rack1R2(config)#int s1/0.1

Rack1R2(config-subif)#band

Rack1R2(config-subif)#bandwidth 20000

Rack1R2(config-subif)#end

___________

Rack1R2#sh ip eigrp topology 192.168.1.1 255.255.255.255

IP-EIGRP (AS 1): Topology entry for 192.168.1.1/32

State is Passive, Query origin flag is 1, 1 Successor(s), FD is 768000

Routing Descriptor Blocks:

192.168.12.1 (Serial1/0.1), from 192.168.12.1, Send flag is 0x0

Composite metric is (768000/128256), Route is Internal

Vector metric:

Minimum bandwidth is 20000 Kbit

Total delay is 25000 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 1

jogillis · ‎06-05-2008

My subinterface has a bvi associated with it. No bandwidth was coded for this bvi so it must have initially used the bandwidth from the subinterface associated with it. When I changed the bandwidth on the subinterface it did not update the bvi bandwidth and eigrp did not get updated (does eigrp use the bvi for its calculation?). Changed the bandwidth on the bvi to reflect the change to the subinterface and eigrp is now doing what I wanted it to do.

I was not doubting you, when you said you did not need to bounce the interface, I was just trying to figure out how my situation was different. It would appear the bvi was the answer. Thanks

Edison Ortiz · ‎06-05-2008

You need to change the bandwidth on the interface running EIGRP.

If the subinterface had an BVI associated to it, it means the subinterface represented the Layer2 connection while the BVI represented the Layer3 instance. EIGRP runs on interfaces with Layer3 (IP) information.

HTH,

__

Edison.

jogillis · ‎06-06-2008

Thanks again. On a side note about the BVI, if I am going to employ QOS over this link using and trusting dscp markings, would I then activate it on the bvi and not the serial interface or do I have to use COS and the layer 2 serial interface.

Edison Ortiz · ‎06-06-2008

Your scenerio is similar to a switch configuration.

Where do you usually place the QoS in a switch, on a SVI (Switch Virtual Interface) or on the L2 switchport?

The answer is the L2 switchport :)

jogillis · ‎06-06-2008

Well we have not deployed QOS yet and the connections between switches in our networks are layer 3 routed ports which are fairly straight forward.