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Which object in RSVP message carried the value configured by "tunnel mpls traffic-eng bandwidth" command?

mtsb
Beginner
Beginner

Hi Experts,

I configured a simple MPLS TE tunnel in my routers and configured it with "tunnel mpls traffic-eng bandwidth 777" command. The tunnel came up fine. I tried to capture the packets (using GNS capture) going out of tunnel head end interface but I could not find out on which message object the value '777' is carried. Can anyone please explain me exactly in which RSVP/OSPF message the bandwidth value is carried?

Thanks,

Madhu

1 Accepted Solution

Accepted Solutions

Mahesh Gohil
Rising star
Rising star

Hello Madhu,

I think it is FLOWSPEC object, not 100% sure

The FLOWSPEC class is defined in RFC 2210. Cisco IOS Software requests Controlled-Load service when reserving a TE tunnel. The FLOWSPEC format is complex and has many things in it that RSVP for MPLS TE doesn't use.

The FLOWSPEC is used in Resv messages—Resv, ResvTear, ResvErr, ResvConf, ResvTearConf. Its only use in MPLS TE is to use the average rate section of the FLOWSPEC to specify the bandwidth desired, in bytes. Not bits. Bytes. So if you configure a tunnel with tunnel mpls traffic-eng 100000 to request 100 Mbps of bandwidth, this gets signalled as 12,500,000 bytes per second (100 Mb is 100,000 Kb is 100,000,000 bits, which is 12,500,000 bytes).


Hope this helps

Regards

Mahesh

View solution in original post

2 Replies 2

Mahesh Gohil
Rising star
Rising star

Hello Madhu,

I think it is FLOWSPEC object, not 100% sure

The FLOWSPEC class is defined in RFC 2210. Cisco IOS Software requests Controlled-Load service when reserving a TE tunnel. The FLOWSPEC format is complex and has many things in it that RSVP for MPLS TE doesn't use.

The FLOWSPEC is used in Resv messages—Resv, ResvTear, ResvErr, ResvConf, ResvTearConf. Its only use in MPLS TE is to use the average rate section of the FLOWSPEC to specify the bandwidth desired, in bytes. Not bits. Bytes. So if you configure a tunnel with tunnel mpls traffic-eng 100000 to request 100 Mbps of bandwidth, this gets signalled as 12,500,000 bytes per second (100 Mb is 100,000 Kb is 100,000,000 bits, which is 12,500,000 bytes).


Hope this helps

Regards

Mahesh

Yes Mahesh, it is in Flowspec but in bytes. I know it could be either in Fspec or Tspec as I see in the output of "show mpls traffic-eng tunnels tunnel1" but forgot about the conversion to bytes and so I was looking for a value of 777 somewwhere in the packet I captured.
I configured with 777 kbps which will be (777x1000/8)=97125 bytes which is listed in the capture below.

FLOWSPEC: Controlled Load: Token Bucket, 97125 bytes/sec.

Thanks a lot for giving me the hint.

Regards,

Madhu

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