Test-driving arbitrary data publishing over BGP

BGP is a routing protocol known for its strength in scaling and resilience. It is also flexible and extensible.  With its Multi-Protocol extension BGP can support distribution of various data types. Still to extend BGP for every new route data type  requires introduction of new address family(AFI/SAFI) and making BGP aware of the new data type.

What if we could just distribute any arbitrary data over BGP without the need for introduction of changes to BGP? Of-course the BGP end point itself cannot decipher the arbitrary data but the data can be passed on to other applications which can make sense of it.

Well this feature is proposed in the following IETF draft

https://tools.ietf.org/html/draft-lapukhov-bgp-opaque-signaling-02

The draft proposes introduction of a generic opaque Address family to allow distributing arbitrary key value pair over BGP.

Testing opaque data dissemination over BGP

While investigating GoBGP for my previous experiment I realized that GoBGP has support for Key Value based opaque data dissemination. So let’s see how we can disseminate a Key Value pair of arbitrary data over BGP.

For this experiment I am using a simple linear topology as shown below.

slide1

Also I have used mininet to simulate the above topology using Linux Network Name Spaces as the BGP speakers.

Starting the topology

Install mininet using apt-get commands as follows

$ sudo apt-get install mininet

Start the default linier topology as follows. This topology has two hosts H1(10.0.0.1) and H2 (10.0.0.2) connected through a switch

$ sudo mn
mininet>

Start GoBGP instances on the hosts. To do this create 2 config files one for each GoBGP instance. The following is an example config file for H1(10.0.0.1).

[global.config]
  as = 64512
  router-id = "10.0.0.1"
[[neighbors]]
[neighbors.config]
  neighbor-address = "10.0.0.2"
  peer-as = 64512
[[neighbors.afi-safis]]
  [neighbors.afi-safis.config]
  afi-safi-name = "opaque"

To start the GoBGP instance use the following command

mininet> h1 ./GO_WA/bin/gobgpd -f ./gobgpd_h1.conf &
mininet> h2 ./GO_WA/bin/gobgpd -f ./gobgpd_h2.conf &

Check the BGP neighbor status

mininet> h1 /home/ubuntu/GO_WA/bin/gobgp nei
Peer        AS  Up/Down State       |#Advertised Received Accepted
10.0.0.2 64512 00:00:24 Establ      |          0        0        0

Also make sure that the neighbor had the capability to publish and consume opaque data

mininet> h1 ./GO_WA/bin/gobgp neigh 10.0.0.2
BGP neighbor is 10.0.0.2, remote AS 64512
  BGP version 4, remote router ID 10.0.0.2
  BGP state = BGP_FSM_ESTABLISHED, up for 1d 05:45:43
  BGP OutQ = 0, Flops = 0
  Hold time is 90, keepalive interval is 30 seconds
  Configured hold time is 90, keepalive interval is 30 seconds
  Neighbor capabilities:
    BGP_CAP_MULTIPROTOCOL:
        opaque: advertised and received
    BGP_CAP_ROUTE_REFRESH:      advertised and received
    BGP_CAP_FOUR_OCTET_AS_NUMBER:       advertised and received
  Message statistics:
                         Sent       Rcvd
    Opens:                  1          1
    Notifications:          0          0
    Updates:                4          0
    Keepalives:          3572       3572
    Route Refesh:           0          0
    Discarded:              0          0
    Total:               3577       3573
  Route statistics:
    Advertised:             3
    Received:               0
    Accepted:               0

Publishing an opaque Key-Value pair

Use the following command to publish any key value pair over BGP connection.

mininet> h1 ./GO_WA/bin/gobgp global rib add key key1 value value1 -a opaque
mininet> h1 ./GO_WA/bin/gobgp global rib add key key2 value value2 -a opaque
mininet> h1 ./GO_WA/bin/gobgp global rib add key key3 value value3 -a opaque

Verify that the opaque data is received on the BGP peers i.e. H2

mininet> h2 ./GO_WA/bin/gobgp global rib -a opaque

  Network Next Hop  Age      Attrs
*>key1    10.0.0.1  00:01:10 [{Origin: ?} {LocalPref: 100} {Value: value1}]
*>key2    10.0.0.1  00:00:09 [{Origin: ?} {LocalPref: 100} {Value: value2}]
*>key3    10.0.0.1  00:00:03 [{Origin: ?} {LocalPref: 100} {Value: value3}]

Conclusion

Publishing arbitrary data over BGP can be used to distribute application specific configuration.  BGP will not try to interpret the opaque data. The data must be used by the application. The draft proposes BGP implementation may provide APIs for the application to publish and consume opaque data.

 

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Published by

Chandan Dutta Chowdhury

Software Engineer

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