508
|
Intermediate System to Intermediate System
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routing information directly with external routers located outside of the routing domains. Level 1-2
systems manage both inter-area and intra-area traffic by maintaining two separate link databases; one for
Level 1 routes and one for Level 2 routes. A Level 1-2 router does not advertise Level 2 routes to a Level 1
router.
To establish adjacencies, each IS-IS router sends different Protocol Data Units (PDU). For IP traffic, the IP
addressing information is included in the IS-IS hello PDUs and the Link State PDUs (LSPs).
This brief overview is not intended to provide a complete understanding of IS-IS; for that, consult the
documents listed in
Multi-Topology IS-IS on page 509
.
IS-IS Addressing
IS-IS PDUs require ISO-style addressing called Network Entity Title (NET). For those familiar with
NSAP addresses, the composition of the NET is identical to an NSAP address, except the last byte is
always 0. The NET is composed of IS-IS area address, system ID, and the N-selector. The last byte is the
N-selector. All routers within an area have the same area portion. Level 1 routers route based on the system
address portion of the address, while the Level 2 routers route based on the area address.
The NET length is variable, with a maximum of 20 bytes and a minimum of 8 bytes. It is composed of the
following:
•
area address. Within your routing domain or area, each area must have a unique area value. The first
byte is called the authority and format indicator (AFI).
•
system address. This is usually the router’s MAC address.
•
N-selector. This is always 0.
Figure 23-1
is an example of the ISO-style address to illustrate the address format used by IS-IS. In this
example, the first five bytes (47.0005.0001) are the area address. The system portion is 000c.000a.4321
and the last byte is always 0.
Figure 23-1. ISO Address Format
variable
6 bytes
1 byte
FN00060a
47.0005.0001.000c.000a.4321.00
N-selector
system-id
area address
Summary of Contents for Force10 E300
Page 1: ...FTOS Configuration Guide FTOS 8 4 2 7 E Series TeraScale C Series S Series S50 S25 ...
Page 32: ...32 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 132: ...132 802 1X w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 310: ...310 Configuration Replace and Rollback w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 330: ...330 Dynamic Host Configuration Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 402: ...402 High Availability w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 462: ...462 Interfaces w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 482: ...482 IPv4 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 506: ...506 IPv6 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 582: ...582 Layer 2 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 642: ...642 Multicast Source Discovery Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 662: ...662 Multiple Spanning Tree Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 690: ...690 Object Tracking w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 754: ...754 PIM Dense Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 784: ...784 PIM Source Specific Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 800: ...800 Power over Ethernet w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 876: ...876 Quality of Service w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 892: ...892 Routing Information Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1006: ...1006 Simple Network Management Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1018: ...1018 SONET SDH w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1048: ...1048 Broadcast Storm Control w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1096: ...1096 Uplink Failure Detection UFD w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1098: ...1098 Upgrade Procedures w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1196: ...1196 C Series Debugging and Diagnostics w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1252: ...1252 Standards Compliance w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1262: ...1262 Index w w w d e l l c o m s u p p o r t d e l l c o m ...