ISIS adjacency across two parallel p2p interfaces

[wintermute000]

I've run into a hilarious scenario when labbing a niche ISIS scenario, probably arising from the fact that ISIS runs underneath IP or whatever upper layer protocols involved.


I have two JunOS vSRXs with two parallel point to point links (two separate VLAN within a vswitch, to be precise)


SP-LAB-P1 ge-0/0/3.0 (10.8.8.1/24) ---> SP-LAB-P4 ge0/0/3.0(10.8.8.2/24)
SP-LAB-P1 ge-0/0/4.0  (10.9.9.1/24) ---> SP-LAB-P4 ge0/0/4.0 (10.9.9.2/24)

Both links can ping fine and I have confirmed the MAC addresses are not duplicated.

When I try to bring ISIS up, I get the following error. The adjacency comes up fine as soon as I disable on of the links.
This would make sense if the interfaces were sharing the same VLAN forming a broadcast domain, but I can confirm they are in different VLANs so act as two different wires.



Any ISIS experts?

Jan  7 23:40:28.395176 Adjacency state change, SP-LAB-P4, state Down -> Initializing
Jan  7 23:40:28.395178     interface ge-0/0/3.0, level 2
Jan  7 23:40:28.395287 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:28.395289 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.395367 ISIS L2 neighbor SP-LAB-P4 on interface ge-0/0/3.0 set 27 secs 0 nsecs
Jan  7 23:40:28.395518 ISIS programmed L1 periodic xmit to 01:80:c2:00:00:14 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:28.395631 ISIS programmed L2 periodic xmit to 01:80:c2:00:00:15 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:28.409938 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:28.409939 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.410145 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:28.410146 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.440844 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:28.440859 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.440956 Adjacency state change, SP-LAB-P4, state Initializing -> Up
Jan  7 23:40:28.440958     interface ge-0/0/3.0, level 2
Jan  7 23:40:28.441003 L2 DR change from SP-LAB-P1.00 to SP-LAB-P4.02 on interface ge-0/0/3.0
Jan  7 23:40:28.441125 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:28.441180 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.441385 ISIS L2 neighbor SP-LAB-P4 on interface ge-0/0/3.0 set 9 secs 0 nsecs
Jan  7 23:40:28.441474 ISIS programmed L1 periodic xmit to 01:80:c2:00:00:14 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:28.441561 ISIS programmed L2 periodic xmit to 01:80:c2:00:00:15 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:28.453954 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:28.453956 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.454077 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:28.454085 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.483191 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:28.483206 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.483387 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:28.483389 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:28.600744 Start L2 route installation for topology unicast
Jan  7 23:40:28.600757   Start route installation for ipv4 routes
Jan  7 23:40:28.600759   End route installation for ipv4 routes
Jan  7 23:40:28.600761   Start route installation for ipv6 routes
Jan  7 23:40:28.600763   End route installation for ipv6 routes
Jan  7 23:40:28.600765   Start route installation for clns routes
Jan  7 23:40:28.600767   End route installation for clns routes
Jan  7 23:40:28.600769 End L2 route installation for topology unicast
Jan  7 23:40:31.246809 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:31.864430 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:31.864461 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.878829 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/3.0
Jan  7 23:40:31.878830 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.908324 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:31.908340 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.908464 Adjacency state change, SP-LAB-P4, state Up -> Down
Jan  7 23:40:31.908466     interface ge-0/0/3.0, level 1
Jan  7 23:40:31.908527 No candidates for L1 DR on ge-0/0/3.0
Jan  7 23:40:31.908612 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:31.908614 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.908863 ISIS L1 neighbor SP-LAB-P4 on interface ge-0/0/3.0 deleted
Jan  7 23:40:31.909274 ISIS programmed L1 periodic xmit to 01:80:c2:00:00:14 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:31.909370 ISIS programmed L2 periodic xmit to 01:80:c2:00:00:15 interface ge-0/0/3.0, interval 9 secs 0 nsecs
Jan  7 23:40:31.923078 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:31.923080 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.923114 ERROR: ISIS ignored a bad packet: IIH with duplicate sysid on interface ge-0/0/4.0
Jan  7 23:40:31.923116 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.937884 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0
Jan  7 23:40:31.937886 Notification not sent due to 5-second throttle as per rfc4444: isisRejectedAdjacency
Jan  7 23:40:31.938067 Adjacency state change, SP-LAB-P4, state Down -> Initializing
Jan  7 23:40:31.938069     interface ge-0/0/3.0, level 1
Jan  7 23:40:31.938158 ERROR: IIH from SP-LAB-P4 without matching addresses, interface ge-0/0/4.0

SP-LAB-P4
  Interface: ge-0/0/3.0, Level: 1, State: Down, Expires in 0 secs
  Priority: 64, Up/Down transitions: 92502, Last transition: 00:00:00 ago
  Circuit type: 3, Speaks: IP, IPv6, MAC address: 0:50:56:ab:e3:1d
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: SP-LAB-P4.00, IP addresses: 10.8.8.2
  Transition log:
  When                  State        Event           Down reason
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA


SP-LAB-P4
  Interface: ge-0/0/3.0, Level: 2, State: Down, Expires in 0 secs
  Priority: 64, Up/Down transitions: 101124, Last transition: 00:00:00 ago
  Circuit type: 3, Speaks: IP, IPv6, MAC address: 0:50:56:ab:e3:1d
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: SP-LAB-P4.00, IP addresses: 10.8.8.2
  Transition log:
  When                  State        Event           Down reason
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA


SP-LAB-P4
  Interface: ge-0/0/4.0, Level: 1, State: Initializing, Expires in 26 secs
  Priority: 64, Up/Down transitions: 92574, Last transition: 00:00:00 ago
  Circuit type: 3, Speaks: IP, IPv6, MAC address: 0:50:56:ab:f7:6c
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: SP-LAB-P4.00, IP addresses: 10.9.9.2
  Transition log:
  When                  State        Event           Down reason
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA


SP-LAB-P4
  Interface: ge-0/0/4.0, Level: 2, State: Initializing, Expires in 26 secs
  Priority: 64, Up/Down transitions: 101920, Last transition: 00:00:00 ago
  Circuit type: 3, Speaks: IP, IPv6, MAC address: 0:50:56:ab:f7:6c
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: SP-LAB-P4.00, IP addresses: 10.9.9.2
  Transition log:
  When                  State        Event           Down reason
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Not Seenself    Not Seenself
  Wed Jan  7 22:58:08   Up           Seenself       
  Wed Jan  7 22:58:08   Down         Error           NBR changed its SNPA

[wintermute000]

Well crammed lots more ISIS, all makes sense now re: the protocol but still confused as to the original fault. It appears on the face of it that it sees the same 'router-id' (sysid or the NET address) then spits the dummy despite coming over a different link. This implies that fundamentally you can't run parallel links across two ISIS routers but I can't find any official reference to this anywhere. 

In case anyone is  interested, following are far superior ways of explaining ISIS than the Juniper fast-track guide or indeed the Cisco official guide

http://blog.ipspace.net/2011/11/junos-day-one-is-is-for-dummies.html
http://blog.ipspace.net/2011/11/multi-level-is-is-in-single-area-think.html
http://www.menog.org/presentations/menog-4/MENOG4-ISIS-Tutorial.pdf