USH Support in BNG

Unified Session History (USH) is a flow based event logging and correlating framework. This chapter provides information about USH support in BNG.

Table 1. Feature History for USH Support in BNG

Release

Modification

Release 6.5.1

This feature is introduced.

This chapter covers these topics:

Overview of USH

Unified Session History (USH) is a flow based event logging and correlating framework. It provides the infrastructure to store the events that occurrs on a subscriber session lifecycle in a central storage, correlating multiple keys of the subscriber, such as, subscriber label, MAC address, IPv4 address, IPv6 address, interface handle etc. It also identifies the normal or errored events in show commands and thereby helps narrow down the reason behind problematic subscriber sessions.

For BNG, MAC address of the subscriber is the primary key. The secondary keys used are:

  • Interface handle

  • Subscriber label

  • IPv4 address and VRF id

  • IPv6 address and VRF id

USH enables processing and storing the events on a per-subscriber basis. New show commands have been introduceded to display the events based on the key provided.

Restrictions for USH in BNG

The following restrictions are applicable to this feature:

  • This feature will not work for routed subscribers as the subscriber MAC address is not unique in the case.

  • When the subscriber is successfully disconnected, only the key events are saved to reduce memory footprint.

Configure USH for BNG

Configuration Steps

The USH feature for BNG is not enabled by default. This is enabled on demand by the following configuration:

Router# configure terminal
Router(config)# subscriber ush enable
Router(config)# interface Bundle-Ether 1.1
Router(config)# interface Bundle-Ether 1.2
Router(config)# commit

Note

The maximum number of access interfaces configured as filter for USH is two. Configuring more than two interfaces shows the following error: 

!!% Max number of monitored interfaces reached: exceeded USH_MAX_FILTER_COUNT interfaces

Verification

In order to view the event history for an active subscriber, use the show command show subscriber session history subscriber-mac command as shown below: 

Router# show subscriber session history subscriber-mac 0020.9400.000c
/oper/ush/&&/key path  mac/0020.9400.000c/0

          STAF event history

Subscriber state: Active

SubscriberMAC:0020.9400.000c

ifhandle: 0x0000cba0

sublabel: 0x00000052

ipv4 Address:192.168.1.42

ipv6 Address: No IPv6 address

vrf:0x60000000 (default)

Time stamp               comp_name       event

----------------------------------------------------------------
11/07/2018 16:34:52:743135       dhcp            Discover pkt procsd

11/07/2018 16:34:52:743135       iedge           IPv4 Start

11/07/2018 16:34:52:747135       aaa             Radiusd recieved Authorization request

11/07/2018 16:34:52:748134       aaa             Radiusd successfully built Access-Request packet

11/07/2018 16:34:52:750134       aaa             Radiusd Successfully sent packet and started timout handler

11/07/2018 16:34:52:753134       aaa             Radiusd recieved Access-Accept

11/07/2018 16:34:52:753134       aaa             Decode radius packet success

11/07/2018 16:34:52:753134       aaa             Radiusd sending reply back to client 

11/07/2018 16:34:52:759133       dhcp            Session Created     - Init state

11/07/2018 16:34:52:760133       dhcp            IP allocated        - Init state

11/07/2018 16:34:52:764132       dhcp            Request pkt procsd  - Post Offer sent

11/07/2018 16:34:52:764132       ipsub           IPSub intf creation started

11/07/2018 16:34:52:764132       ipsub           IPSub init callback from Ifmg

11/07/2018 16:34:52:764132       ipsub           IPSub session start event to iEdge

11/07/2018 16:34:52:764132       ipsub           IPSub init to Ifmgr

11/07/2018 16:34:52:884114       ipsub           IPSub received VRF details

11/07/2018 16:34:52:951103       iedge           SUBDB produce done

11/07/2018 16:34:52:976099       ipsub           IPSub RIB details added

11/07/2018 16:34:53:078084       ipsub           IPSub session up

11/07/2018 16:34:53:079084       iedge           IPv4 Up

11/07/2018 16:34:53:079084       dhcp            Session DPM success

Information about the last instance of the subscriber session can be displayed using the show subscriber session history subscriber-mac subscriber MAC address disconnected command. 

Router# show subscriber session history subscriber-mac 0010.9400.0094 disconnected 

STAF event history
Subscriber state: Successfully disconnected 
SubscriberMAC:0010.9400.0094
ifhandle: 0x00000260
sublabel: 0x000025d7
ipv4 Address:200.0.0.29 
ipv6 Address: 
vrf:0x60000000 (default)
Time stamp                       comp_name       event 
---------------------------------------------------------------- 
05/12/2016 12:45:35:328697       dhcp            Discover pkt procsd
05/12/2016 12:45:35:328697       iedge           IPv4 Start
05/12/2016 12:45:38:412225       ipsub           IPSub session up
05/12/2016 12:45:38:417224       iedge           IPv4 Up
05/12/2016 12:45:38:422223       iedge           SUBDB produce done
06/12/2016 07:07:12:330971       dhcp            Lease expired for client

If the subscriber session is errored, the complete event information is stored for further reference. This information can be retrived by using the show subscriber session history subscriber-mac subscriber MAC address errored command. 

Router# show subscriber session history subscriber-mac 0020.9400.000c errored

/oper/ush/&&/key path  mac/0020.9400.000c/2

          STAF event history

Subscriber state: Errored 

SubscriberMAC:0020.9400.000c

ifhandle: 0x00000000

sublabel: 0x00000051

ipv4 Address: No IPv4 address

ipv6 Address: No IPv6 address

Time stamp               comp_name       event 

---------------------------------------------------------------- 

11/07/2018 16:32:28:386225       dhcp            Discover pkt procsd

11/07/2018 16:32:28:386225       iedge           IPv4 Start

11/07/2018 16:32:28:389225       aaa             Radiusd recieved Authorization request

11/07/2018 16:32:28:391224       aaa             Radiusd successfully built Access-Request packet

11/07/2018 16:32:28:392224       aaa             Radiusd Successfully sent packet and started timout handler

11/07/2018 16:32:33:783399       aaa             Radiusd Successfully sent packet and started timout handler

11/07/2018 16:32:38:790633       aaa             Radiusd Successfully sent packet and started timout handler

11/07/2018 16:32:43:801866       aaa             Radiusd Successfully sent packet and started timout handler

11/07/2018 16:32:48:808100       aaa             Radius packet sending failed  Reason: 'RADIUS' detected the 'fatal' condition 'No server information is available’

11/07/2018 16:32:48:808100       iedge           policy rule failed  Reason: 'AAA_BASE' detected the 'fatal' condition 'Invalid state (aaa base lib error)’

11/07/2018 16:32:48:809100       iedge           Disconnect session

When USH is enabled, it keeps track of the statistics of sessions that are created, destroyed and errored in the system, over a 10 minute interval. This can be viewed using the command show subscriber session history analytics . 

Router# show subscriber session history analytics

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
[28/01/2017 00:46:15:716111 - 28/01/2017 00:46:58:576552]
---------------------------------------------------------
Flows Created  :       43
Flows Completed:       42
Error Summary:
------------
  [ 0]: 0x45349600 - 'qos-ma' detected the 'warning' condition 'Multiple policies configured on an interface/direction without specifying the merge option’
    Count:   42
    Last Instance:      28/01/2017 00:46:58:162811
      MAC:0000:0000:0001, SUBLBL:0x61, IFH:0x2c10