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What is linked EPS bearer and why it is required ?`

+3 votes
What is linked EPS bearer and why it is required ?`
posted Oct 12, 2014 by Upma

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2 Answers

+3 votes

When UE is trying to connect with a APN first time then a default bearer is created and one IP address is allocated to UE. If UE is trying to create any dedicated bearer with same APN then this dedicated bearer is linked to the default bearer and UE does not need new IP as this dedicated bearer is linked to the default bearer. Suppose in any reason if default bearer is going to be released by core network then the associated dedicated bearer(those are linked with this default bearer ) will be released by the core network.

answer Oct 12, 2014 by Veer Pal Singh Yadav
+2 votes

When an LTE attaches to network, it establishes at least one default bearer to provide always IP on service. This default bearer is nothing but linked bearer.

Linked bearer is associated with one PDN gateway. UE may have multiple dedicated bearers which are associated with same PDN gateway. In that case, if UE sends PDN dis-connectivity request for that PDN, network would be able to releases all the associated bearers along with that linked bearer. In other works, linked bearer is primary and others bearers are secondary.

answer Oct 12, 2014 by Salil Agrawal
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0 votes

Is EPS bearer ID and RAB ID common for all UE ? or RAB ID will be unique for default bearer ?
Please, explain

+2 votes


Pardon me, this is just a theoretical question. Not started my real testing yet. But so meantime trying to see I handle the basic possible scenarios.

In the CCR message of type (Initial Request), lets say PCRF receives both the "QOS" (containing APN AMBR UL and APN AMBR DL) and "Default Bearer QOS" AVP (containing QCI and ARP).
As of now, in my basic code, I return the QOS based on apn info received on "Called-station-ID" AVP. Will it be ok..Or is there any better suggestions on this ?


+1 vote

Hi All,

It is mentioned in different websites that in LTE max. of 8 DRB can be established per UE. But as per page 652 of 36.331 V13.2.0, the max no. of DRB is 11.
"maxDRB INTEGER ::= 11 -- Maximum number of Data Radio Bearers"

Based on what source are we saying that max. DRB in LTE is 8 and not 11.

It was mentioned in one of the old threads the following:

If EPS bearer ID is = x +4 ;
DRB ID = x;
Logical Channel ID = x + 2

I found the above relationship of DRB ID & EPS Bearer ID to be true for one of the eNB vendors but not for another one.

EPS ID is 5 and DRB ID is 4 instead of 1. Can somebody comment in this?
NOTE : All these ranges is with respect to DRB establishment

EPS Bearer ID Range is INTEGER (0..15) (But 0-4 is reserved so we use starting from 5 )
DRB ID Range is INTEGER (1..32) (As in LTE max 8 DRB can be established per UE so we use from 1-8)
Logical Channel ID range for DRBs is INTEGER (3..10) ( For for DRB1 we use 3 as logical channed ID)


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