Subject: [Isis-wg] Interface IP addresses from IS-IS

From: [email-masked]
Date: Tue, 11 Oct 2005 18:20:10 -0400

Hi guys,

Does any of the IS-IS packets contains the IP addresses of all the interfaces of
router runnning IS-IS?

I looked at TLV type 132, but it requires at least one interface IP address
only, rest are optional. The TLV type 128 can give you the prefix and netmask
but not the exact IP address.

Any info will be appreciated.

rupinder makkar

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From: "Parker, Jeff" <[email-masked]>
Date: Wed, 12 Oct 2005 10:16:28 -0400

The router may be advertising some of the networks reachable from some
interfaces, and may be advertising the router ID (aka loopback address) with
a TE TLV. 

- jeff parker

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From: Hannes Gredler <[email-masked]>
Date: Wed, 12 Oct 2005 17:03:24 +0200

> Does any of the IS-IS packets contains the IP addresses of all the interfaces of

LSPs (if traffic-engineering is enabled on a link) may contain subTLV 6,8
      to the extended IS reach TLV 22.

i.e. see below a tcpdump output of an IS-IS LSP:

18:28:54.259841 IS-IS, length 333
         L2 LSP, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
           lsp-id: 0102.5500.6110.00-00, seq: 0x00000005, lifetime:  1198s
           chksum: 0x59e3 (correct), PDU length: 333, Flags: [ L1L2 IS ]
             Area address(es) TLV #1, length: 14
               Area address (length: 13): 47.0005.80ff.f800.0000.0108.0001
             Protocols supported TLV #129, length: 2
               NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
             Traffic Engineering Router ID TLV #134, length: 4
               Traffic Engineering Router ID: 10.255.6.110
             IPv4 Interface address(es) TLV #132, length: 4
               IPv4 interface address: 10.255.6.110
             Hostname TLV #137, length: 8
               Hostname: schnapps
             IS Reachability TLV #2, length: 12
               IsNotVirtual
               IS Neighbor: 0102.5507.0001.00, Default Metric: 10, Internal
             Extended IS Reachability TLV #22, length: 94
               IS Neighbor: 0102.5507.0001.00, Metric: 10, sub-TLVs present (83)
                 IPv4 interface address subTLV #6, length: 4, 10.40.2.1
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 IPv4 neighbor address subTLV #8, length: 4, 10.40.2.2
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 Unreserved bandwidth subTLV #11, length: 32
                   TE-Class 0: 154.520 Mbps
                   TE-Class 1: 116.640 Mbps
                   TE-Class 2: 77.760 Mbps
                   TE-Class 3: 38.880 Mbps
                   TE-Class 4: 155.520 Mbps
                   TE-Class 5: 116.640 Mbps
                   TE-Class 6: 77.760 Mbps
                   TE-Class 7: 38.880 Mbps
                 Reservable link bandwidth subTLV #10, length: 4, 155.520 Mbps
                 Maximum link bandwidth subTLV #9, length: 4, 155.520 Mbps
                 Administrative groups subTLV #3, length: 4, 0x00000000
                 Bandwidth Constraints (old) subTLV #12, length: 17
                 Bandwidth Constraints Model ID: Russian dolls (0)
                   Bandwidth constraint CT0: 155.520 Mbps
                   Bandwidth constraint CT1: 116.640 Mbps
                   Bandwidth constraint CT2: 77.760 Mbps
                   Bandwidth constraint CT3: 38.880 Mbps
             IPv4 Internal Reachability TLV #128, length: 72
               IPv4 prefix:    10.255.6.110/32, Distribution: up, Metric: 0, Internal
               IPv4 prefix:       10.40.2.0/30, Distribution: up, Metric: 10, Internal
               IPv4 prefix:       10.40.1.0/30, Distribution: up, Metric: 20, Internal
               IPv4 prefix:       10.40.3.0/30, Distribution: up, Metric: 20, Internal
               IPv4 prefix:     10.255.70.1/32, Distribution: up, Metric: 10, Internal
               IPv4 prefix:   10.255.71.212/32, Distribution: up, Metric: 20, Internal
             Extended IPv4 Reachability TLV #135, length: 54
               IPv4 prefix:    10.255.6.110/32, Distribution: up, Metric: 0
               IPv4 prefix:       10.40.2.0/30, Distribution: up, Metric: 10
               IPv4 prefix:       10.40.1.0/30, Distribution: up, Metric: 20
               IPv4 prefix:       10.40.3.0/30, Distribution: up, Metric: 20
               IPv4 prefix:     10.255.70.1/32, Distribution: up, Metric: 10
               IPv4 prefix:   10.255.71.212/32, Distribution: up, Metric: 20
             IPv6 reachability TLV #236, length: 22
               IPv6 prefix: abcd::10:255:6:110/128, Distribution: up, Metric: 0, Internal

> but not the exact IP address.

TLV 132 is typically used in IIHs - some implementations add also the IP address of the
loopback IP adress packeged in TLV 132 in LSPs.

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From: [email-masked]
Date: Wed, 12 Oct 2005 16:29:32 -0400

Hi guys,

Thanks for the response.

The TE TLV was only defined in RFC 3784 and may not be present in most 
deployed
systems. Further, I am seeing older Cisco boxes running IS-IS that only 
seem to
advertise the IP for one interface. Does this mean that there are many 
deployed
IS-IS systems which do not advertise their interface IP addresses?

rgds,

rupinder makkar

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From: "Don Goodspeed" <[email-masked]>
Date: Wed, 12 Oct 2005 13:41:23 -0700

Correct.  For TE TLVs, some implementations advertise all router
interfaces while others like the one below only advertise one
reachable IP address unless there is an active nbr on that 
interface.  Note that the subnets for all active ISIS interfaces
should be included in the TE IP reachability TLVs though.

Think OSPF stub interfaces (those w/out nbrs), only the subnet is
advertised in the router LSA, not the specific IP address.

-don

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of [email-masked]
Sent: Wednesday, October 12, 2005 1:30 PM
To: [email-masked]
Subject: Re: [Isis-wg] Interface IP addresses from IS-IS

Hi guys,

Thanks for the response.

rgds,

rupinder makkar