Jan 3 2009

ISIS over Frame-Relay

Configuring ISIS over frame-relay requires an additional command due to the fact that ISIS packets do not use IP at layer 3 but rather use CLNS.

Consider the topology below.

frame-isis

Watch the video below or alternatively download it and watch it on your iPod .

The Flash plugin is required to view this object.

The commands used in the configuration can be found below.

R1
!
frame-relay switching
!
interface Serial1/0
ip address 10.0.0.1 255.255.255.252
ip router isis
encapsulation frame-relay
clockrate 128000
no arp frame-relay
frame-relay map clns 200 broadcast
frame-relay map ip 10.0.0.2 200
no frame-relay inverse-arp
frame-relay intf-type dce
!
router isis
net 49.0001.0000.0000.0001.00
is-type level-1

R2

!
interface Serial1/1
ip address 10.0.0.2 255.255.255.252
ip router isis
encapsulation frame-relay
no arp frame-relay
frame-relay map clns 200 broadcast
frame-relay map ip 10.0.0.1 200
no frame-relay inverse-arp
isis circuit-type level-1
!
router isis
net 49.0001.0000.0000.0002.00

By zismail • CCIE SP, iPod, IS-IS • 4 • Tags: ,

Jan 2 2009

ISIS wide metrics

Be default ISIS caps ISIS metrics greater than 63.

To address this limitation a new IS-IS TLV was defined to overcome the limited 6-bit metric of 63.  This TLV known as TLV Type 135 increased the per-link metric range from <0-63> to <1-16777214> ie the new TLV has 24-bits for the ISIS metric.

This new range can be seen under the interface config mode as shown below.

R2(config)#interface loopback 0
R2(config-if)#isis metric ?
<1-16777214>  Default metric

Consider the topology below.

metric-style

We will attempt to increase the metric of the R2 loopback to greater than 63 with and without wide-metrics enabled.

The video below shows how to configure and verify the use of wide metrics in ISIS.  Click here to download the video and watch it on your iPod.

The Flash plugin is required to view this object.

The commands used in the video are as below:-

R1

interface FastEthernet1/0
ip router isis
!
router isis
net 49.0001.0000.0000.0001.00
is-type level-2-only
metric-style wide
passive-interface Loopback0de>

R2

interface Loopback0
isis metric 10000
!
interface FastEthernet1/0
ip router isis
!
router isis
net 49.0001.0000.0000.0002.00
is-type level-2-only
metric-style wide
passive-interface Loopback0

R3

interface FastEthernet1/0
ip router isis
!
interface FastEthernet1/1
ip router isis
!
router isis
net 49.0001.0000.0000.0003.00
is-type level-2-only
metric-style wide
passive-interface Loopback0
!

To verify the wide metric on R1 use the command below.

R1#show isis database R2.00-00 detail

IS-IS Level-2 LSP R2.00-00
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
R2.00-00              0x0000000E   0x1A31        428               0/0/0
Area Address: 49.0001
NLPID:        0xCC
Hostname: R2
IP Address:        2.2.2.2
Metric: 10         IS-Extended R3.02
Metric: 10000      IP 2.2.2.2/32
Metric: 10         IP 10.0.0.4/30

By zismail • CCIE SP, iPod, IS-IS, Traffic Engineering • 0 • Tags: , , ,

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