bgp load balance

densmadensma Member Posts: 40 ■■□□□□□□□□
i asked this a while on group study but didnt get any response.
when ask to do bgp load balance is it necessary to export policy into forwarding table for multipath load balancing.

what i observed, (R3-T1/T2 case study example) load balance with multipath only install one prefix in forwarding table. unless you export policy to load balance in fowarding table.

the other way around. (R4-C1 case study example) load balance with multihop automatically handle forwarding table load balance.

do you know with multipath load balance if it require especially in JNCIP lab to export policy to fowarding table?

here EBGP R3-T1-T2 example


[email protected]# edit protocols bgp group t1-t2

[edit protocols bgp group t1-t2]
[email protected]# show
multipath;
neighbor 172.16.0.18 {
description T2;
peer-as 65222;
}
neighbor 172.16.0.14 {
description T1;
peer-as 65222;
}

[edit protocols bgp group t1-t2]
[email protected]# run show bgp summary
Groups: 3 Peers: 6 Down peers: 0
Table Tot Paths Act Paths Suppressed History Damp State Pending
inet.0 50 45 0 0 0 0
Peer AS InPkt OutPkt OutQ Flaps Last Up/Dwn State|#Active/Received/Damped...
172.16.0.14 65222 33 23 0 0 8:32 13/13/0 0/0/0
172.16.0.18 65222 36 26 0 0 9:14 13/13/0 0/0/0
10.0.3.4 65412 1232 1471 0 0 11:04:50 13/16/0 0/0/0
10.0.3.5 65412 1228 1465 0 0 11:02:49 3/4/0 0/0/0
10.0.6.1 65412 1260 1525 0 0 11:03:02 1/2/0 0/0/0
10.0.6.2 65412 1233 1522 0 0 11:02:58 2/2/0 0/0/0



[edit protocols bgp group t1-t2]
[email protected]# run show route forwarding-table destination 130.130.1/24
Routing table: inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
130.130.1.0/24 user 0 172.16.0.18 ucst 479 14 fxp4.0

Routing table: __juniper_private1__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 83 1

Routing table: __juniper_private2__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 139 1

[edit protocols bgp group t1-t2]
[email protected]# exit

[edit]
[email protected]# edit policy-options policy-statement lb

[edit policy-options policy-statement lb]

[edit policy-options policy-statement lb]
[email protected]# set from neighbor 172.16.0.14

[edit policy-options policy-statement lb]
[email protected]# set from neighbor 172.16.0.18

[edit policy-options policy-statement lb]


[edit policy-options policy-statement lb]
[email protected]# set then load-balance per-packet

[edit policy-options policy-statement lb]
[email protected]# show
from neighbor [ 172.16.0.14 172.16.0.18 ];
then {
load-balance per-packet;
}

[edit policy-options policy-statement lb]
[email protected]# exit

[edit]
[email protected]# edit routing-options forwarding-table

[edit routing-options forwarding-table]
[email protected]# set export lb

[edit routing-options forwarding-table]
[email protected]# exit

[edit]
[email protected]# run show route forwarding-table destination 130.130.1/24
Routing table: inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
130.130.1.0/24 user 0 172.16.0.18 ucst 479 14 fxp4.0

Routing table: __juniper_private1__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 83 1

Routing table: __juniper_private2__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 139 1

[edit]
[email protected]# commit
commit complete

[edit]
[email protected]# run show route forwarding-table destination 130.130.1/24
Routing table: inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
130.130.1.0/24 user 0 ulst 131076 15
172.16.0.14 ucst 480 3 fxp3.0
172.16.0.18 ucst 479 4 fxp4.0

Routing table: __juniper_private1__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 83 1

Routing table: __juniper_private2__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 139 1

[edit]
[email protected]#

HERE'S R4-C1 MULTIHOP EXAMPLE

[email protected]# edit protocols bgp group c1

[edit protocols bgp group c1]
[email protected]# show
local-address 10.0.3.4;
neighbor 200.200.0.1 {
description c1;
multihop;
authentication-key "$9$.fQnEhrlMX"; ## SECRET-DATA
peer-as 65010;
}

[edit protocols bgp group c1]
[email protected]# exit

[edit]
[email protected]# run show route 200.200.1/24

inet.0: 61 destinations, 64 routes (61 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

200.200.1.0/24 *[BGP/170] 00:06:21, localpref 100, from 200.200.0.1
AS path: 65010 I
> to 172.16.0.6 via fxp3.0
to 172.16.0.10 via fxp4.0


[email protected]# run show route forwarding-table destination 200.200.1/24
Routing table: inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
200.200.1.0/24 user 0 indr 131077 16
ulst 131076 2
172.16.0.6 ucst 475 6 fxp3.0
172.16.0.10 ucst 474 2 fxp4.0

Routing table: __juniper_private1__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 83 1

Routing table: __juniper_private2__.inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 rjct 139 1

[edit]
[email protected]#

Comments

  • AldurAldur Juniper Moderator Member Posts: 1,460
    densma wrote: »
    i asked this a while on group study but didnt get any response.
    when ask to do bgp load balance is it necessary to export policy into forwarding table for multipath load balancing.

    ...

    do you know with multipath load balance if it require especially in JNCIP lab to export policy to fowarding table?

    Just simply using multipath will allow 2 bgp routes to be activite in the route table at the same time, effectively skipping steps 9 and 10 in the bgp selection algorithm. However this does nothing for load balancing since only one route is installed in the forwarding table.

    You are correct in that to really do load balancing you need to have a export policy in the forwarding table that tells it to do this.

    Do you need to know this for the test? Well I can't say much about that without breaking NDA. But if you feel that you need to apply a load balancing export policy to the forwarding table I don't think that would cause any harm, even if they don't ask for it. Either way it's a simple matter so I wouldn't stress about it to much.
    "Bribe is such an ugly word. I prefer extortion. The X makes it sound cool."

    -Bender
  • hoogen82hoogen82 Member Posts: 272
    Ask the proctor if the question is unclear and whether control and data plane load balancing needs to be acheived. There was a post from Harry Reynolds regarding this, check the juniper nsp forum. He did agree with folks to have load balancing on both planes... But always check with proctor..
    IS-IS Sleeps.
    BGP peers are quiet.
    Something must be wrong.
  • zoidbergzoidberg Member Posts: 365
    i think i did only control plane, and i believe that was all cool, but i can't remember for sure and things may change over time. definitely check with the proctor, or, just do both, takes 10 seconds and doesn't hurt.

    remember, you're marked on results, not config. so in this case doing both is likely a-ok and good way to cover your butt. and for other tasks, don't get hung up on worrying about configuring everything as it is done in the books. do it the way you like, adhering to the required constraints, and as long as you get the results they are asking for, you're golden.
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