I am facing a very strange issue with regard to IS-IS Interface Metric / Cost calculation in Juniper MX. We have configured a reference bandwidth of 1000G on all routers.This by definition means an ae interface (with 2 x 10G member Links) would yield a cost of 50G (1000G/20G = 50). We can see this using command 'show isis interface' on Junos.
However in my case , we have two routers that are directly connected using Bundle Link (AE Link) that has 2 x 10G member Links. IS-IS is running between them. Now each router should have interface metric of 50. But from CLI we see that R1 has interface metric of 33 ! while R2 has interface metric of 50 (which is correct). So How R1 is saying interface metric is 33 when it has only 2 x 10G member links. (Cost should be 50 while Junos is saying a metric of 33).
Junos on R1 is 13.3R7-S3.1 while on R2 it is 15.1R6-S5. Both are MX960 series routers.
Many Thanks ... I now share CLI output to support my query :-
<------------------------------R2------------------------------------------->
R2> show lacp interfaces ae16
Aggregated interface: ae16
LACP state: Role Exp Def Dist Col Syn Aggr Timeout Activity
xe-8/3/2 Actor No No Yes Yes Yes Yes Fast Active
xe-8/3/2 Partner No No Yes Yes Yes Yes Fast Active
xe-8/0/0 Actor No No Yes Yes Yes Yes Fast Active
xe-8/0/0 Partner No No Yes Yes Yes Yes Fast Active
LACP protocol: Receive State Transmit State Mux State
xe-8/3/2 Current Fast periodic Collecting distributing
xe-8/0/0 Current Fast periodic Collecting distributing
R2> show configuration interfaces ae16
apply-groups [ xge-if-parameters ubfd-ae ];
description Connected to R1;
aggregated-ether-options {
bfd-liveness-detection {
neighbor 192.168.0.38;
local-address 192.168.0.13;
}
lacp {
active;
periodic fast;
}
}
unit 3 {
apply-groups core-ifl-parameters;
vlan-id 3;
family inet {
address 10.10.20.2/30;
}
family mpls;
}
R2> show configuration protocols isis interface ae16.3
apply-groups isis-ifl-parameters-wo-bfd;
ldp-synchronization;
R2> show configuration protocols isis
inactive: traceoptions {
file isis-log;
flag state;
}
reference-bandwidth 1000g;
lsp-lifetime 65535;
level 1 disable;
level 2 {
authentication-key ""; ## SECRET-DATA
authentication-type md5;
wide-metrics-only;
}
interface ae27.3 {
apply-groups isis-ifl-parameters-wo-bfd;
ldp-synchronization;
}
interface ae29.3 {
apply-groups isis-ifl-parameters;
ldp-synchronization;
}
interface lo0.0;
R2> show isis interface ae16.3
IS-IS interface database:
Interface L CirID Level 1 DR Level 2 DR L1/L2 Metric
ae16.3 2 0x1 Disabled Point to Point 50/50
<------------------------------R1------------------------------------------->
R1> show lacp interfaces ae16
Aggregated interface: ae16
LACP state: Role Exp Def Dist Col Syn Aggr Timeout Activity
xe-0/2/9 Actor No No Yes Yes Yes Yes Fast Active
xe-0/2/9 Partner No No Yes Yes Yes Yes Fast Active
xe-8/0/6 Actor No No Yes Yes Yes Yes Fast Active
xe-8/0/6 Partner No No Yes Yes Yes Yes Fast Active
LACP protocol: Receive State Transmit State Mux State
xe-0/2/9 Current Fast periodic Collecting distributing
xe-8/0/6 Current Fast periodic Collecting distributing
R1> show configuration interfaces ae16
apply-groups [ xge-if-parameters ubfd-ae ];
description Connected to R2;
aggregated-ether-options {
bfd-liveness-detection {
neighbor 192.168.0.13;
local-address 192.168.0.38;
}
link-speed 10g;
lacp {
active;
periodic fast;
}
}
unit 3 {
apply-groups core-ifl-parameters;
vlan-id 3;
family inet {
address 10.10.20.1/30;
}
family iso;
}
R1> show configuration interfaces ae16.3
apply-groups core-ifl-parameters;
vlan-id 3;
family inet {
address 10.10.20.1/30;
}
family iso;
R1> show configuration protocols isis
reference-bandwidth 1000g;
lsp-lifetime 65535;
spf-options {
delay 50;
holddown 5000;
rapid-runs 3;
}
level 1 disable;
level 2 {
authentication-key ""; ## SECRET-DATA
authentication-type md5;
wide-metrics-only;
}
interface ae16.3 {
apply-groups isis-ifl-parameters-wo-bfd;
ldp-synchronization;
}
}
interface ae45.3 {
apply-groups isis-ifl-parameters;
ldp-synchronization;
level 2 metric 33;
}
interface ae46.3 {
apply-groups isis-ifl-parameters;
ldp-synchronization;
level 2 metric 33;
}
interface lo0.0 {
passive;
}
R1> show isis interface ae16.3
IS-IS interface database:
Interface L CirID Level 1 DR Level 2 DR L1/L2 Metric
ae16.3 2 0x1 Disabled Point to Point 33/33
R1> show route 192.168.0.13
inet.0: 38694 destinations, 113966 routes (38470 active, 1 holddown, 226 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.0.13/32 *[IS-IS/18] 1d 06:58:47, metric 33
> to 10.10.20.2 via ae16.3
