From: Reisner, Tim (TR126568@exchange.DAYTONOH.NCR.com)
Date: Tue Dec 02 2003 - 09:39:33 GMT-3
From a Cisco White Paper on Eigrp:
The rate at which EIGRP sends hello packets is called the hello interval,
and you can adjust it per interface with the ip hello-interval eigrp
command. The hold time is the amount of time that a router will consider a
neighbor alive without receiving a hello packet. The hold time is typically
three times the hello interval, by default, 15 seconds and 180 seconds. You
can adjust the hold time with the ip hold-time eigrp command.
Note that if you change the hello interval, the hold time is not
automatically adjusted to account for this change - you must manually adjust
the hold time to reflect the configured hello interval.
It is possible for two routers to become EIGRP neighbors even though the
hello and hold timers don't match. The hold time is included in the hello
packets so each neighbor should stay alive even though the hello interval
and hold timers don't match.
While there is no direct way of determining what the hello interval is on a
router, you can infer it from the output of show ip eigrp neighbor on the
neighboring router.
If you have the output of a show ip eigrp neighbor command from your Cisco
device, you can use Output Interpreter to display potential issues and
fixes. To use Output Interpreter , you must be a registered customer, be
logged in, and have JavaScript enabled.
router#show ip eigrp neighbor
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 10.1.1.2 Et1 13 12:00:53 12 300 0 620
0 10.1.2.2 S0 174 12:00:56 17 200 0 645
rp-2514aa#show ip eigrp neighbor
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 10.1.1.2 Et1 12 12:00:55 12 300 0 620
0 10.1.2.2 S0 173 12:00:57 17 200 0 645
rp-2514aa#show ip eigrp neighbor
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 10.1.1.2 Et1 11 12:00:56 12 300 0 620
0 10.1.2.2 S0 172 12:00:58 17 200 0 645
The value in the Hold column of the command output should never exceed the
hold time, and should never be less than the hold time minus the hello
interval (unless, of course, you are losing hello packets). If the Hold
column usually ranges between 10 and 15 seconds, the hello interval is 5
seconds and the hold time is 15 seconds. If the Hold column usually has a
wider range - between 120 and 180 seconds - the hello interval is 60 seconds
and the hold time is 180 seconds. If the numbers do not seem to fit one of
the default timer settings, check the interface in question on the
neighboring router - the hello and hold timers may have been configured
manually.
Document link:
http://www.cisco.com/en/US/customer/tech/tk365/tk207/technologies_white_pape
r09186a0080094cb7.shtml
regards,
Tim Reisner
CCIE #10418
CCDA
NCR Corp.
High Availability Networking Global Support Center
Phone: (763)535-3274
Cell: (763)227-3179
Email: Tim.Reisner@NCR.com
-----Original Message-----
From: Peng Zheng [mailto:zpnist@yahoo.com]
Sent: Tuesday, December 02, 2003 2:46 AM
To: ccielab@groupstudy.com
Subject: How to check eigrp hello-interval for an interface
As subject.
Thanks.
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