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I'm trying to setup a basic ISIS routing policy for a network with the following configurations:

Server A:

router1.home.domain1.net# show running-config

Current configuration:
!
hostname router1.domain1.net
password abcdefg
!
interface he-wan0
!
interface lan0
!
interface lo
!
interface serverconn
 ip router isis interconnections
 isis circuit-type level-1-2
 isis hello-interval 5
 isis priority 1
!
interface wan0
!
interface wlp2s0
!
router isis interconnections
 net 49.2112.4120.2420.0000.00
 metric-style narrow
!
line vty
!
end

Server B:

server0.domain2.com(config-if)# show running-config

Current configuration:
!
password abcdefg2
!
interface domain1connect
 ip router isis interconnections
 isis circuit-type level-1-2
 isis hello-interval 5
 isis priority 10
!
interface eno1
!
interface eno2
!
interface ens3f0
!
interface ens3f1
!
interface lo
!
interface userlan
!
router isis interconnections
 net 49.2113.1872.1900.0000.00
 metric-style narrow
!
line vty
!
end

At the moment, I can see traffic (via tcpdump) from domain1.net:

root@router1:~# tcpdump -vi serverconn
tcpdump: listening on serverconn, link-type EN10MB (Ethernet), capture size 262144 bytes
19:59:08.010409 IS-IS, length 1497
        L1 Lan IIH, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          source-id: 1872.1900.0000,  holding time: 50s, Flags: [Level 1, Level 2]
          lan-id:    0000.0000.0000.00, Priority: 10, PDU length: 1497
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.2113
            Protocols supported TLV #129, length: 1
              NLPID(s): IPv4 (0xcc)
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 10.255.253.4
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 168
19:59:10.200352 IS-IS, length 1497
        L2 Lan IIH, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          source-id: 4120.2420.0000,  holding time: 50s, Flags: [Level 1, Level 2]
          lan-id:    0000.0000.0000.00, Priority: 1, PDU length: 1497
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.2112
            Protocols supported TLV #129, length: 1
              NLPID(s): IPv4 (0xcc)
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 10.255.253.1
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 255
            Padding TLV #8, length: 168

I can't seem to figure out why the two routers don't see each other, and any help would be highly appreciated.

I've already tried using the same area ID and setting it up as a Level 1 connection, but that doesn't seem to work either.

Thanks.

adalal
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    The routing process is assuming a 1500 byte MTU and is padding the PDU's accordingly. Can you verify that this is, in fact, correct and that the intervening infrastructure is configured accordingly? Also - there's really no great reason to be running L1-L2 (or even L1-only) in most setups unless there's some need for summarization and such. I'd recommend L2-only. – rnxrx Jan 02 '18 at 04:02
  • Thanks for the L1/L2 recommendations. It's something I'll certainly keep in mind. Regarding the MTU issue, I've tried connecting a third server with similar settings directly connected by a ethernet cable on the same network - to rule out MTU issues with the MTU value set to 1500. Unfortunately, I still get no results when I run 'show isis neighbor'. – adalal Jan 02 '18 at 10:57

0 Answers0