[j-nsp] ISIS between ERX 1440 and MX960

david.roy at orange-ftgroup.com david.roy at orange-ftgroup.com
Thu May 19 13:24:57 EDT 2011

Hi all,

I'm trying to establish an ISIS L2 adjacency between an ERX (Junose is new for me) and 1 MX without success :  I double checked the mtu, subnet, Area (not checked for L2), authentication key (I tried simple and MD5 types)

The problem seems to be at the ERX side. Indeed, the MX receives well the IIH of the ERX and put its state to Init, then it sends an IIH to the ERX. At the ERX level, IIH is discarded (at the Interface level : Input Discard counter). I don't understand why. I guess there is a MTU issue with the hello padding process but I'm not sure.

Config at the MX side

family iso;
faimly inet address

family iso address 49.0001.xxx

protocol isis
level 2 {
    authentication-key sdjskdjskd;
    authentication-type md5;
interface ge-2/2/2.0 {
level 1 disable;
level 2 {
 hello-authetication-key FOO;
 hello-authetication-type md5;

Config at the ERX side :

router isis 1234
is-type level-2-only
net 49.0001.xxx
domain-message-digest-key 1 hmac-md5 FOO
passive-interface loopback50

int gi 12/0
ip router isis 1234
isis circuit-type level-2-only
isis message-digest-key 1 hmac-md5 FOO level-2

I tried to monitor ISIS packet at the MX side. I noticed that the PDU length of the MX IIH is equal to 1492 and the ERX one is equal to 1497. Moreover, the protocol capabilities of the MX are IPv4 and IPv6 and for the ERX that are CLNP and IPv4. 

Any help would be most welcome.


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