R0106-HP MSR Router Series Layer 3 - IP Routing Configuration Guide(V7)

154
Setting the LSDB overload bit
By setting the overload bit in sent LSPs, a router informs other routers of failures that make it unable to
select routes and forward packets.
When an IS-IS router cannot record the complete LSDB, for example, because of memory insufficiency,
it will calculate wrong routes. To make troubleshooting easier, temporarily isolate the router from the IS-IS
network by setting the overload bit.
To set the LSDB overload bit:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter IS-IS view or IS-IS
IPv4 unicast topology
view.
• Enter IS-IS view:
isis [ process-id ] [ vpn-instance vpn-instance-name ]
• Enter IS-IS IPv4 unicast topology view:
a. isis [ process-id ] [ vpn-instance
vpn-instance-name ]
b. cost-style { wide | wide-compatible }
c. address-family ipv4 [ unicast ]
d. topology topo-name tixd tid
Use either method.
3. Set the overload bit.
set-overload [ on-startup [ [ start-from-nbr system-id
[ timeout1 [ nbr-timeout ] ] ] | timeout2 ] [ allow { external
| interlevel } * ]
By default, the
overload bit is not
set.
Configuring the ATT bit
A Level-1-2 router sends Level-1 LSPs with an ATT bit to inform the Level-1 routers that it can reach other
areas.
Configuring IS-IS not to calculate the default route through the ATT bit
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3. Configure IS-IS not to calculate
the default route through the ATT
bit.
ignore-att
By default, IS-IS uses the ATT bit
to calculate the default route.
Setting the ATT bit of Level-1 LSPs
Ste
p
Command Remarks
1. Enter system view.
system-view
N/A
2. Enter IS-IS view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3. Set the ATT bit of Level-1 LSPs.
set-att { always | never }
By default, the ATT bit is not set
for Level-1 LSPs.