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IS-IS Adjacency

I have two routers( a 7206 and a 7513) connected through 3 E1 links and they establish adjacency in only one link. The mtu is the same on both sides, there´s no phisical erros on the links, but two of them present the "INIT" state at the "sh clns neighboors" command. On the 7206 router, the holdtime is about 290, while on the 7513 it´s 26.

The only difference I have found is at "debug isis adj...":

ISIS-Adj: Sending serial IIH on Serial2/1/6:0, length 44

ISIS-Adj: Sending serial IIH on Serial2/1/5:0, length 1499

ISIS-Adj: Sending serial IIH on Serial2/1/4:0, length 1499

Serial2/1/6:0 has the good link!!!

Any suggestion?

Thanks

7 REPLIES
Silver

Re: IS-IS Adjacency

Have you checked to ensure that all your interfaces are configured to be either point to point or multi point?

Hope this helps,

Don

New Member

Re: IS-IS Adjacency

Don,

These are E1 interfaces connected point-to-point and there´s no subinterfaces configured.

Thanks

Rogerio

Silver

Re: IS-IS Adjacency

Rogerio,

The only other thing I can think of is that IIH's are padded to max MTU and might be getting dropped somewhere. You can disable this in your ISIS routing process by typing the following:

no hello padding point-to-point

This will disable padding on your point to point links only. If this is not the fix you might send the following from your routers.

show clns in (just your broken serials)

show clns protocol

show clns neighbors

Hope this fixes your issue,

Don

New Member

Re: IS-IS Adjacency

Hi, Don....

The configurations is correct with the "no hello paddin..." command..

Here are the informations:

ROUTER A

Serial4/1:0 is up, line protocol is up

Checksums enabled, MTU 1500, Encapsulation HDLC

ERPDUs enabled, min. interval 10 msec.

RDPDUs enabled, min. interval 100 msec., Addr Mask enabled

Congestion Experienced bit set at 4 packets

CLNS fast switching enabled

CLNS SSE switching disabled

DEC compatibility mode OFF for this interface

Next ESH/ISH in 38 seconds

Routing Protocol: IS-IS

Circuit Type: level-1-2

Interface number 0x6, local circuit ID 0x105

Level-2 Metric: 100, Priority: 64, Circuit ID: br-vot-rp-ra1.05

Number of active level-2 adjacencies: 0

Next IS-IS Hello in 6 seconds

Serial4/2:0 is up, line protocol is up

Checksums enabled, MTU 1500, Encapsulation HDLC

ERPDUs enabled, min. interval 10 msec.

RDPDUs enabled, min. interval 100 msec., Addr Mask enabled

Congestion Experienced bit set at 4 packets

CLNS fast switching enabled

CLNS SSE switching disabled

DEC compatibility mode OFF for this interface

Next ESH/ISH in 40 seconds

Routing Protocol: IS-IS

Circuit Type: level-1-2

Interface number 0x7, local circuit ID 0x106

Level-2 Metric: 100, Priority: 64, Circuit ID: br-vot-rp-ra1.06

Number of active level-2 adjacencies: 1

Next IS-IS Hello in 6 seconds

sh clns prot

IS-IS Router:

System Id: C8CD.FD92.0000.00 IS-Type: level-2

Manual area address(es):

49.0000.0000.28bd.0000

Routing for area address(es):

49.0000.0000.28bd.0000

Interfaces supported by IS-IS:

FastEthernet5/0 - IP

Serial4/2:0 - IP

Serial4/1:0 - IP

Serial4/0:0 - IP

Serial3/5:0 - IP

Serial3/3:0 - IP

Serial3/1:0 - IP

Serial3/0:0 - IP

Redistribute:

static (on by default)

Distance for L2 CLNS routes: 110

RRR level: none

Generate narrow metrics: none

Accept narrow metrics: none

Generate wide metrics: level-1-2

Accept wide metrics: level-1-2

sh clns neig

System Id Interface SNPA State Holdtime Type Protocol

br-bru-ac-rc1 Se3/1:0 *HDLC* Up 28 L2 IS-IS

br-bru-ac-rc1 Se3/0:0 *HDLC* Up 27 L2 IS-IS

br-bru-ac-rc2 Se3/5:0 *HDLC* Up 23 L2 IS-IS

br-cas-ce-rc2 Se4/1:0 *HDLC* Up 261 IS ES-IS

br-cas-ce-rc2 Se4/0:0 *HDLC* Up 265 IS ES-IS

br-cas-ce-rc2 Se4/2:0 *HDLC* Up 22 L2 IS-IS

ROUTER B

Serial2/1/4:0 is up, line protocol is up

Checksums enabled, MTU 1500, Encapsulation HDLC

ERPDUs enabled, min. interval 10 msec.

RDPDUs enabled, min. interval 100 msec., Addr Mask enabled

Congestion Experienced bit set at 4 packets

CLNS fast switching enabled

CLNS SSE switching disabled

DEC compatibility mode OFF for this interface

Next ESH/ISH in 30 seconds

Routing Protocol: IS-IS

Circuit Type: level-1-2

Interface number 0x1, local circuit ID 0x101

Level-2 Metric: 50, Priority: 64, Circuit ID: br-cas-ce-rc2.01

Number of active level-2 adjacencies: 0

Next IS-IS Hello in 7 seconds

Serial2/1/5:0 is up, line protocol is up

Checksums enabled, MTU 1500, Encapsulation HDLC

ERPDUs enabled, min. interval 10 msec.

RDPDUs enabled, min. interval 100 msec., Addr Mask enabled

Congestion Experienced bit set at 4 packets

CLNS fast switching enabled

CLNS SSE switching disabled

DEC compatibility mode OFF for this interface

Next ESH/ISH in 47 seconds

Routing Protocol: IS-IS

Circuit Type: level-1-2

Interface number 0x2, local circuit ID 0x102

Level-2 Metric: 100, Priority: 64, Circuit ID: br-cas-ce-rc2.02

Number of active level-2 adjacencies: 0

Next IS-IS Hello in 6 seconds

SH CLNS PROT

IS-IS Router:

System Id: C8CD.FD2F.0000.00 IS-Type: level-2

Manual area address(es):

49.0000.0000.28bd.0000

Routing for area address(es):

49.0000.0000.28bd.0000

Interfaces supported by IS-IS:

POS12/0/0 - IP

ATM9/1/0.3 - IP

ATM9/1/0.2 - IP

ATM9/1/0.1 - IP

POS4/0/0 - IP

Serial2/1/6:0 - IP

Serial2/1/5:0 - IP

Serial2/1/4:0 - IP

POS0/0/0 - IP

Redistribute:

static (on by default)

Distance for L2 CLNS routes: 110

RRR level: none

Generate narrow metrics: none

Accept narrow metrics: none

Generate wide metrics: level-1-2

Accept wide metrics: level-1-2

#SH CLNS NEIG

System Id Interface SNPA State Holdtime Type Protocol

br-vot-rp-ra1 Se2/1/4:0 *HDLC* Init 24 L2 IS-IS

br-vot-rp-ra1 Se2/1/5:0 *HDLC* Init 24 L2 IS-IS

br-vot-rp-ra1 Se2/1/6:0 *HDLC* Up 25 L2 IS-IS

Silver

Re: IS-IS Adjacency

From your previous post it appears that "no hello padding" is not functioning properly due to IIH's being 1499 out of the interfaces that are not functioning properly. Have you tried applying this "no isis hello padding" on each of the interfaces just to try it.

There is not to much, as long as your capabilities (MTU,Wide Metric Support, etc) match that would keep these Adjacencies from coming up. If the SystemID's were duplicate it would stay in Init as well but you'd see this in your logs unless your logging level is set to something very high.

I am also assuming that other traffic (IP,CDP, etc) can pass through these curcuits and that there are no ACLs that would be limiting reception of these IIH's through them. If the no hello padding does not work you might send your router isis config as well just to see if there is something in there. Also your running IOS version might help out. Might be a bug.

Also here is a good link on whats all in a WAN IIH if your interested:

http://www.cisco.com/warp/public/cc/pd/iosw/prodlit/insys_wp.htm

Hope this helps,

Don

New Member

Re: IS-IS Adjacency

Hello, Don

Thanks for your help.

Looking carefully to this problem we detected some input erros on these interfaces that were counted as "abort frames". At the "show log" there were logs of "protocol up/down". So, we called up the Carrier Transmission area to look at SDH circuits and found sincronysm problems.

Thanks a lot.

Rogerio Galvao

Silver

Re: IS-IS Adjacency

Rogerio,

Glad to hear you got it resolved. I was worried I had forgotten ISIS... ;)

Have a great day,

Don

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