Table of Contents
Advertisement
IS-IS
Copyright © 2010, Juniper Networks, Inc.
During a warm restart after a system failover, the SRP module can take several
minutes to resume the normal exchange of UDP/IP packets to applications. During
this restart time, the E Series router does not send or receive dead peer detection
(DPD) keepalives, which are used to verify connectivity between the router and its
peers. The length of the restart time depends on the number of interfaces—if the
restart time is too long, remote peers might determine that the connection from
them to the E Series router is broken and then shut down an IPSec tunnel that has
DPD enabled. In the worst case, all IPSec tunnels might be shut down. [Defect ID
65132]
When IS-IS is configured on a static PPP interface, the IS-IS neighbor does not come
up if you remove the IP address from the interface and then add the IP address back
to the interface.
Work-around: When you remove and add back the IP address, you must also remove
the IS-IS configuration from the interface and then add the configuration back to the
interface by issuing the no router isis and router isis commands.
When you run IS-IS on back-to-back virtual routers (VRs) in an
IS-IS-over-bridged-Ethernet configuration and do not configure different IS-IS
priority levels on each VR, a situation can occur in which both VRs elect themselves
as the designated intermediate system (DIS) for the same network segment.
This situation occurs because the router uses the same MAC address on all bridged
Ethernet interfaces by default. When both VRs have the same (that is, the default)
IS-IS priority level, the router must use the MAC address assigned to each interface to
determine which router becomes the DIS. Because each interface in an
IS-IS-over-bridged-Ethernet configuration uses the same MAC address, however, the
router cannot properly designate the DIS for the network segment. As a result, both
VRs elect themselves as the DIS for the same network segment, and the
configuration fails. [Defect ID 72367]
Work-around: To ensure proper election of the DIS when you configure IS-IS over
bridged Ethernet for back-to-back VRs, we recommend that you use the isis network
point-to-point command in Interface Configuration mode to configure IS-IS to
operate using point-to-point (P2P) connections on a broadcast circuit when only
two routers (or, in this case, two VRs) are on the circuit. Issuing this command tears
down the current existing IS-IS adjacency in that link and reestablishes a new
adjacency.
If you perform a stateful SRP switchover operation on a router with IS-IS previously
configured on the device, the IS-IS application takes longer than the normal duration
(approximately 40 seconds) to restart after the switchover is completed. The time
that it takes for IS-IS to restart after a stateful switchover causes a large delay in the
transmission of hello packets with restart TLV (type 211) from the restarting router to
neighboring routers. Because of the delay in transmission of hello packets to
neighboring routers, active adjacencies are not maintained between the restating
router and other routers in the IS-IS domain. To avoid adjacencies being reset, we
recommend that you increase the hold timers for the IS-IS protocol to appropriate
values, based on the level of complexity of the network and configuration settings, so
as to enable IS-IS graceful restart to be completed successfully. [Defect ID 90546]
Release 11.3.0
Known Behavior
27
Advertisement
Table of Contents
