IOS XE 15.5
IOS XR 5.3
The topology for this demo:
This post will be a look at "auto-bandwidth or auto-bw". The idea behind this feature is make better use of bandwidth allocation for a tunnel rather than just give the tunnel all the bandwidth that the "bandwidth" command specified. Leveraging just the bandwidth definitely works and has it's use but if you specify 100 Mbps as the bandwidth reservation and the average bandwidth use is 10 Mbps, the tunnel is being under utilized. Auto BW would take a look at the utilization over a given period of time, 5 minutes by default, and allocate the highest bandwidth seen in that period of time to the tunnel.
interface Tunnel7
ip unnumbered Loopback0
load-interval 60
tunnel mode mpls traffic-eng
tunnel destination 192.168.1.6
tunnel mpls traffic-eng priority 7 7
tunnel mpls traffic-eng bandwidth 6
tunnel mpls traffic-eng affinity 0x0 mask 0x0
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng auto-bw frequency 600 max-bw 100 min-bw 10
R3#show mpls traffic-eng tunnels tunnel 7 | sec auto-bw
auto-bw: (600/328) 0 Bandwidth Requested: 10
Samples Missed 0: Samples Collected 0
The auto-bw (600/xxx) means that every 600 seconds, the tunnel will get checked for bandwidth optimization. The "0" next to it would have the bandwidth allocated. Bandwidth requested is 10 here, for 10 Kbps. The drawback in my lab is that the platform limit is 100000 bps.
R3#sh ip rsvp reservation filter session-type 7 tunnel-id 7
Destination Tun Sender TunID LSPID Next Hop I/F Fi Serv BPS
192.168.1.6 192.168.1.3 7 7 10.14.3.14 Gi1.143 SE LOAD 6K
As you can see the 6 Kbps of bandwidth reservation are signaled and working. However, since we are requesting less than the minimal limit that the auto-bw option can support, we won't actually see any modification.
Thanks for stopping by!
Rob Riker, CCIE #50693
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