4.1.a Implement and troubleshoot MPLS operations

or the mpls ldp ID…

roger perkin has  a nice article on this here…http://www.rogerperkin.co.uk/ccie/index.php/mpls/mpls-ldp-router-id-loopback0-force/ 

it is also discussed in DeGhein’s MPLS Fundamentals in chapter 4

the router id preference for ldp works like it does for ospf and bgp… the theory behind the value of using the loopback in all cases is well documented…

pe1(config)#do sh mpls ldp discovery
Local LDP Identifier:
192.168.14.1:0
Discovery Sources:
Interfaces:
FastEthernet1/0 (ldp): xmit/recv
LDP Id: 192.168.24.2:0
FastEthernet1/1 (ldp): xmit/recv
LDP Id: 192.168.34.4:0

note this is the highest active interface ip address…

pe1(config)#do sh ip int brie
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        192.168.15.1    YES manual up                    up
FastEthernet0/1        192.168.16.1    YES manual up                    up
FastEthernet1/0        192.168.12.1    YES NVRAM  up                    up
FastEthernet1/1        192.168.14.1    YES NVRAM  up                    up
FastEthernet2/0        unassigned      YES NVRAM  administratively down down
FastEthernet2/1        unassigned      YES NVRAM  administratively down down
Loopback0              1.1.1.1         YES manual up                    up

also note that there is an active loopback so what gives?

i added the loopback after the LID had already been determined… you can force it to change…

pe1(config)#mpls ldp router-id lo0 force
pe1(config)#
*Apr 12 11:39:57.776: %LDP-5-INFO: default: LDP ID removed
*Apr 12 11:39:57.792: %LDP-5-NBRCHG: LDP Neighbor 192.168.34.4:0 (1) is DOWN (LDP Router ID changed)
*Apr 12 11:39:57.792: %LDP-5-NBRCHG: LDP Neighbor 192.168.24.2:0 (2) is DOWN (LDP Router ID changed)

pe1(config)#do sh mpls ldp disco
Local LDP Identifier:
1.1.1.1:0
Discovery Sources:
Interfaces:
FastEthernet1/0 (ldp): xmit/recv
LDP Id: 192.168.24.2:0
FastEthernet1/1 (ldp): xmit/recv
LDP Id: 192.168.34.4:0

sh mpls ldp disco detail will give you hello and holdtime’s…

pe1(config)#do sh mpls ldp disco detail
Local LDP Identifier:
1.1.1.1:0
Discovery Sources:
Interfaces:
FastEthernet1/0 (ldp): xmit/recv
Enabled: Interface config
Hello interval: 5000 ms; Transport IP addr: 1.1.1.1
LDP Id: 192.168.24.2:0
Src IP addr: 192.168.12.2; Transport IP addr: 192.168.24.2
Hold time: 15 sec; Proposed local/peer: 15/15 sec
Reachable via 192.168.24.0/24
Password: not required, none, in use
Clients: IPv4, mLDP
FastEthernet1/1 (ldp): xmit/recv
Enabled: Interface config
Hello interval: 5000 ms; Transport IP addr: 1.1.1.1
LDP Id: 192.168.34.4:0
Src IP addr: 192.168.14.4; Transport IP addr: 192.168.34.4
Hold time: 15 sec; Proposed local/peer: 15/15 sec
Reachable via 192.168.34.0/24
Password: not required, none, in use
Clients: IPv4, mLDP

sh tcp brief is also your buddy here:

pe2#sh tcp brie
TCB       Local Address               Foreign Address             (state)
68883684  3.3.3.3.35933               1.1.1.1.179                  ESTAB
688822F4  3.3.3.3.48108               2.2.2.2.646                  ESTAB
69507584  3.3.3.3.646                 4.4.4.4.40376                ESTAB