1. Since the load imbalance occurs when traffic is forwarded from Router C to Router B and Router C originally exists on the link, traffic does not change whether Router B is added or not. Therefore, the load balancing problem is not caused by the traffic model.
2. The on-site Huawei technical support personnel check whether load balancing is performed across the routes using the display ip routing-table command.
The command output shows that the routes destined for POS 1/0/0 and POS 2/0/0 participate in load balancing.
<HUAWEI> display ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------Routing Tables: Public
Destinations : 18409 Routes : 21796
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 O_ASE 150 1 D X.X.5.45 Pos2/0/0
O_ASE 150 1 D X.X.5.49 Pos1/0/0
The preceding command output shows only part of the segments as evidence. To check whether the traffic is forwarded in route load balancing mode, check the entire routing table.
IP routes can participate in load balancing, but the traffic is not load balanced over the two POS links. Therefore, the traffic is not forwarded in the IP route load balancing mode. LSP load balancing may be performed during the forwarding process.
1. The on-site Huawei technical support personnel check whether load balancing is performed across the LSPs.
They check the LSP information about load balancing on POS 1/0/0 and POS 2/0/0 respectively using the following commands. The command output shows that only on LSP that is established on POS 2/0/0 exists. This result matches the fact that no traffic reaches POS 1/0/0.
<HUAWEI> display mpls lsp outgoing-interface Pos 1/0/0 // No information is displayed.
<HUAWEI> display mpls lsp outgoing-interface Pos 2/0/0
-----------------------------------------------------------------------------
LSP Information: LDP LSP
-----------------------------------------------------------------------------
FEC In/Out Label In/Out IF Vrf Name
X.X.5.16/30 NULL/3 -/Pos2/0/0
X.X.5.16/30 1041/3 -/Pos2/0/0
X.X.7.1/32 1043/3 -/Pos2/0/0
X.X.7.1/32 NULL/3 -/Pos2/0/0
After the display mpls lsp outgoing-interface Pos 1/0/0 command is run, no command output is displayed, which indicates that no LSP is established on POS 1/0/0.
2. The on-site Huawei technical support personnel analyze the cause why no LSP is established on POS 1/0/0.
To locate the cause, they check the LDP session establishment using the display mpls ldp peer command. The following command output shows that Router C's LDP peer is established on POS 2/0/0. This may be caused by a configuration problem.
<HUAWEI> display mpls ldp peer
LDP Peer Information in Public network
----------------------------------------------------------------------------
Peer-ID Transport-Address Discovery-Source
----------------------------------------------------------------------------
The configuration information is omitted here.
X.X1.5.7:0 X.X.116.1 GigabitEthernet14/0/0
X.X.7.1:0 X.X.5.5 Pos2/0/0 ====No LDP peer is established on POS 1/0/0.
----------------------------------------------------------------------------
TOTAL: 10 Peer(s) Found.
3. The on-site Huawei technical support personnel check the configurations on the POS interfaces and find that the transport-address command is run on both POS 1/0/0 and POS 2/0/0 to configure the current interface addresses to be transport addresses.
LDP sessions over multiple links between two LSRs must be established based on the same transport address. Therefore, to establish an LDP session over multiple links between Router B and Router C and implement load balancing, cancel the preceding configuration.
<HUAWEI> display current-configuration
......
interface Pos1/0/0
link-protocol ppp
undo shutdown
ip address X.X.5.6 255.255.255.252
isis enable 99
isis circuit-level level-2
mpls
mpls ldp
mpls ldp transport-address interface
#
interface Pos2/0/0
link-protocol ppp
ip address X.X.5.2 255.255.255.252
isis enable 99
isis circuit-level level-2
mpls
mpls ldp
mpls ldp transport-address interface
