Routing

Hi All,

I have 4 logical routers LDP configured . 

in inet.3 routing table only 3 entries are observed

root@JTB_MX80_1# run show route protocol ldp logical-system p1

inet.0: 23 destinations, 23 routes (23 active, 0 holddown, 0 hidden)

inet.3: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

192.168.1.1/32 *[LDP/9] 1d 01:37:44, metric 1
> to 172.22.210.1 via lt-1/0/0.220
192.168.5.2/32 *[LDP/9] 1d 01:37:43, metric 1
> to 172.22.201.2 via lt-1/1/0.11
192.168.5.3/32 *[LDP/9] 09:00:43, metric 1
> to 172.22.201.2 via lt-1/1/0.11, Push 299936

mpls.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

299904 *[LDP/9] 1d 01:37:44, metric 1
> to 172.22.210.1 via lt-1/0/0.220, Pop
299904(S=0) *[LDP/9] 1d 01:37:44, metric 1
> to 172.22.210.1 via lt-1/0/0.220, Pop
299920 *[LDP/9] 1d 01:37:43, metric 1
> to 172.22.201.2 via lt-1/1/0.11, Pop
299920(S=0) *[LDP/9] 1d 01:37:43, metric 1
> to 172.22.201.2 via lt-1/1/0.11, Pop
299936 *[LDP/9] 09:00:43, metric 1
> to 172.22.201.2 via lt-1/1/0.11, Swap 299936

However, in LDP database we have two different paths

root@JTB_MX80_1# run show ldp database logical-system p1
Input label database, 192.168.5.1:0--192.168.1.1:0
Label Prefix
3 192.168.1.1/32
299904 192.168.5.1/32
299936 192.168.5.2/32
299952 192.168.5.3/32

Output label database, 192.168.5.1:0--192.168.1.1:0
Label Prefix
299904 192.168.1.1/32
3 192.168.5.1/32
299920 192.168.5.2/32
299936 192.168.5.3/32

Input label database, 192.168.5.1:0--192.168.5.2:0
Label Prefix
299920 192.168.1.1/32
299888 192.168.5.1/32
3 192.168.5.2/32
299936 192.168.5.3/32

Output label database, 192.168.5.1:0--192.168.5.2:0
Label Prefix
299904 192.168.1.1/32
3 192.168.5.1/32
299920 192.168.5.2/32
299936 192.168.5.3/32

Why there is no label operation for the path 192.168.5.1:0--192.168.5.2:0

Br,

Serkan

Hi,

"show ldp database"  output shows the labels advertised and recieved from the direct LDP  neigbors. These are not the MPLS paths.

Input label database, 192.168.5.1:0--192.168.1.1:0    => Labels recieved from LDP neigbor 192.168.1.1
Output label database, 192.168.5.1:0--192.168.1.1:0 => Labels advertised  to LDP neigbor 192.168.1.1

Input label database, 192.168.5.1:0--192.168.5.2:0  => Labels recieved from LDP neigbor 192.168.5.2
Output label database, 192.168.5.1:0--192.168.5.2:0 => Labels advertised  to LDP neigbor 192.168.5.2

Regards,

Moses N

Hi Moses,

the point that I do not understand is Why the label operation for 192.168.5.1:0--192.168.1.1:0 only is shown in inet.3 instead of 192.168.5.1:0--192.168.5.2:0.

Br,

Serkan 

Hi,

I think you are confused with the label values.

Labels shown in

inet.3  - Ingress LSR labels

mpls.0 - Transit LSR labels

LDP database - Full set of labels recieved from and advertised to direct LDP neighbors.

Labels are allocated based on per platform. That means same label values can be allocated  by different routers for different prefix / same prefix.

I believe your topology  should be like

192.168.5.3  ====== 5.2 ======= 5.1 =========== 1.1  ( or a ring)

so, inet.3 shows  ingress label opertion to reach 5.3 ( that is hwy you see Push 299936)

5.2 and 1.1 are directly connected routers, so we don't need any labels to reach them ( PHP behaviour)

Regards,

Moses N

thanks a lot Moses,

i got it now