Understanding ‘traffic-engineering credibility-protocol-preference’

This article provides information on how to configure the TED protocol to prefer one IGP over the other, when multiple IGPs are configured for traffic engineering.

TED protocol preference can be influenced to prefer one IGP over the other via the following command :

set protocols traffic-engineering credibility-protocol-preference

1	set protocols traffic-engineering credibility-protocol-preference

Topology used:

lo0 192.168.1.1 lo0 192.168.1.2 +---------+ +---------+ | +----------------------+ | | r1 |ge-0/2/0 ge-0/2/1| r2 | +---------+10.1.2.1 10.1.2.2+---------+

1 2 3 4 5

lo0 192.168.1.1                  lo0 192.168.1.2      +---------+                      +---------+      |         +----------------------+         |      |  r1     |ge-0/2/0      ge-0/2/1|   r2    |      +---------+10.1.2.1      10.1.2.2+---------+

• For illustration purposes, the r1 and r2 logical systems are used.
• Traffic engineering is enabled on both the ISIS and OSPF routing protocols.
• By default, ISIS is preferred as the TED protocol
• When a particular links information is populated in TED by both OSPF and ISIS, TED will prefer ISIS over OSPF, as by default, the credibility of ISIS is higher than that of OSPF.
• This selection occurs before the link`s traffic-engineering metric is evaluated or compared.
• Versions 9.6 and 10.0 or later work as described above. For versions before 9.6 / 10.0, TED credibility is not enforced.
• The default credibility/protocol preference can be changed to prefer one protocol over the other, by using the set protocols <protocol> traffic-engineering credibility-protocol-preference hidden command.

Configuration – Logical system r1:

Outputs:

• By default, ISIS is preferred in TED.
• The show ted protocol command can be used to view the TED preference:
  
  [edit] lab@black# run show ted protocol logical-system r1 Jun 25 16:32:42 Protocol name Credibility Self node IS-IS(2) 2 black-r1.00(192.168.1.1) < ISIS preferred, credibility 2 IS-IS(1) 1 black-r1.00(192.168.1.1) OSPF(0) 0 black-r1.00(192.168.1.1) [edit] lab@black# run show ted protocol logical-system r2 Jun 25 16:34:36 Protocol name Credibility Self node IS-IS(2) 2 black-r2.00(192.168.1.2) < ISIS preferred, credibility 2 IS-IS(1) 1 black-r2.00(192.168.1.2) OSPF(0) 0 black-r2.00(192.168.1.2)

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

  [edit] lab@black# run show ted protocol logical-system r1 Jun 25 16:32:42 Protocol name        Credibility  Self node IS-IS(2)             2            black-r1.00(192.168.1.1) < ISIS preferred, credibility 2 IS-IS(1)             1            black-r1.00(192.168.1.1) OSPF(0)              0            black-r1.00(192.168.1.1)   [edit] lab@black# run show ted protocol logical-system r2     Jun 25 16:34:36 Protocol name        Credibility  Self node IS-IS(2)             2            black-r2.00(192.168.1.2) < ISIS preferred, credibility 2 IS-IS(1)             1            black-r2.00(192.168.1.2) OSPF(0)              0            black-r2.00(192.168.1.2)

Configuration change:

r1 is configured to prefer OSPF in TED, whereas r2 is left as is:

Configuration:
Outputs: