MPLS TE reservable bw

If you don't configure the ip rsvp bandwidth command, the default reservable bandwidth advertised for that interface is 0. A common cause of tunnels not coming up during testing or initial deployment of MPLS Traffic Engineering is configuring a TE tunnel to require a certain amount of bandwidth but forgetting to configure available bandwidth on any link. See Chapter 11 for more details on how to detect this.

You don't have to specify a value for the total-reservable-bandwidth value in the ip rsvp bandwidth command. If you don't specify a value, the default is 75 percent of the link bandwidth. The link bandwidth is determined by the interface type or the per-interface bandwidth command.

The above section is a copy and paste from a cisco press te book, i'm not sure what is meant regarding the default being 75%. As per below i can configure the rsvp reserved bandwidth to be 100% of the link bandwidth. The tunnel can be configured to use all the allocated bandwidth. By default the bandwidth on a link is 0, where is the 75% coming into the equation?

R1#sh ip rsvp int
interface    allocated  i/f max  flow max sub max 
Fa0/0        0          0        0        0   
Fa0/1        0          0        0        0   
R1#
R1#sh int fa0/0 | i BW
  MTU 1500 bytes, BW 10000 Kbit/sec, DLY 1000 usec, 
R1#
R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#int fa0/0
R1(config-if)#ip rsvp band
R1(config-if)#ip rsvp bandwidth 10000
R1(config-if)#do sh ip rsvp int
interface    allocated  i/f max  flow max sub max 
Fa0/0        0          10M      10M      0   
Fa0/1        0          0        0        0   
R1(config-if)#int tun 1
R1(config-if)#tunn mod
*Mar  6 11:32:28.651: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to down
R1(config-if)#tunn mode mpls traffic-eng 
R1(config-if)#ip unn
R1(config-if)#ip unnumbered lo0
R1(config-if)#tunn dest 2.2.2.2
R1(config-if)#tunn mpls traffic-eng bandwidth 10000
R1(config-if)#tunn mpls traffic-eng aff            
R1(config-if)#tunn mpls traffic-eng affinity 0x0 mask 0x0
R1(config-if)#tunn mpls traffic-eng path-option 1 dynamic 
R1(config-if)#
*Mar  6 11:33:51.907: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to up
R1(config-if)#do sh mpls traf tunn tunn 1

Name: R1_t1                               (Tunnel1) Destination: 2.2.2.2
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected

    path option 1, type dynamic (Basis for Setup, path weight 10)

  Config Parameters:
    Bandwidth: 10000    kbps (Global)  Priority: 7  7   Affinity: 0x0/0x0
    Metric Type: TE (default)
    AutoRoute:  disabled  LockDown: disabled  Loadshare: 10000    bw-based
    auto-bw: disabled

  InLabel  :  - 
  OutLabel : FastEthernet0/0, implicit-null
  RSVP Signalling Info:
       Src 1.1.1.1, Dst 2.2.2.2, Tun_Id 1, Tun_Instance 1
    RSVP Path Info:
      My Address: 1.1.1.1   
      Explicit Route: 10.0.12.2 2.2.2.2 
      Record Route:  NONE
      Tspec: ave rate=10000 kbits, burst=1000 bytes, peak rate=10000 kbits
    RSVP Resv Info:
      Record Route:  NONE
      Fspec: ave rate=10000 kbits, burst=1000 bytes, peak rate=10000 kbits
  Shortest Unconstrained Path Info:
    Path Weight: 10 (TE)
    Explicit Route: 10.0.12.2 2.2.2.2 
  History:
    Tunnel:
      Time since created: 1 minutes, 42 seconds
      Time since path change: 27 seconds
    Current LSP:
      Uptime: 27 seconds
R1(config-if)#do sh ip rsvp int
interface    allocated  i/f max  flow max sub max 
Fa0/0        10M        10M      10M      0   
Fa0/1        0          0        0        0   
R1(config-if)#

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Comments

deth1k

You are reading it wrong mate

"If you don't specify a value" that means ip rsvp bandwidth "no value" i.e command on it's own

HTH

lrb

mpls traffic-eng tunnels turns on RSVP on the interface but doesn't tell how much is the reseverable bandwidth, so you get nothing. If you enable ip rsvp bandwidth on the interface with no percentage, the default is 75% of the bandwidth command.

Here's some testing on my 15.4 IOU (E0/0 is a 10Mb interface).

R3#show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF   
         
R3#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R3(config)#mpls traffic-eng tunnels
R3(config)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF    
        
R3(config)#int e0/0
R3(config-if)#mpls traffic-eng tunnels
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          0        0        0    
   
R3(config-if)#ip rsvp bandwidth
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          7500K    7500K    0   
    
R3(config-if)#bandwidth 100
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          75K      75K      0 
     
R3(config-if)#no bandwidth 100           
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          7500K    7500K    0  
  
R3(config-if)#ip rsvp bandwidth 50
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          50K      50K      0  

R3(config-if)#ip rsvp bandwidth percent 100
R3(config-if)#do show ip rsvp interface
interface    rsvp  allocated  i/f max  flow max sub max  VRF            
Et0/0        ena   0          10M      10M      0

EdTheLad

Thanks for that, that's probably one of the most ridiculous configs i've seen yet. By default when i config "ip rsvp bandwidth" without a value it reserves 75% of the interface bw, like i'm going to config that without a value, if i don't require a specific value. This is what happens when coding is out sourced to india lol.