Cisco EA4500 ARP Table?

Hello,
I am trying to do the following:
Add a static entry in your router’s ARP table with your device’s MAC address, so it won’t be removed after a time of inactivity (time that depends on the ARP table timeout).
I can't seem to find the ARP table in the settings. Any help would be appreciated.
Thanks

I believe this router doesn't have that feature. Tried searching the net but it’s showing that only business class routers have this feature. This router only has the DHCP client table.

Similar Messages

Arp table and mac table in cisco 4503 switch

Hi all,
I have a problem with 4503 switch
I have 7 highend servers in my lan i.e 5hp and 2dell servers.
Each server has 4 network interface cards(1g). so 7*4=28 ports.
I have create vlan 70, ip add is 10.70.70.1
I have assign ip address to servers like
first server         10.70.70.2, 10.70.70.12,
Second server   10.70.70.3, 10.70.70.13,
Third server        10.70.70.4, 10.70.70.14,
fourth Server       10.70.70.5, 10.70.70.15, 10.70.70.25, 10.70.70.35
fifth server           10.70.70.6, 10.70.70.16, 10.70.70.26, 10.70.70.36
sixth server          10.70.70.7, 10.70.70.17, 10.70.70.27, 10.70.70.37
seventh server      10.70.70.8, 10.70.70.18, 10.70.70.28, 10.70.70.38
The problem is in four interfaces each server, only one or two interfaces are pinging, remaining interface are not pinging.
for example in the first server i can able to ping 10.70.70.12- macid 60eb.69d2.a2aa
                                            i can't able to ping 10.70.70.2- macid 60eb.69d2.a2ab
second, fourth, fifth, sixth, and seventh continiously pinging successfully.
for example in fourth server i can able to ping 10.70.70.5 macid -b499.bafe.9c98
                                         i can able to ping 10.70.70.15 macid-b499.bafe.9c98
                                         i can able to ping 10.70.70.25 macid-b499.bafe.9c98
                                         i can able to ping 10.70.70.35 macid-b499.bafe.9c98
now you understand what is the problem, which server i am not getting pinging that arp table shows each interface separte mac address
                                                   which server i am getting pinging that arp table shows each interface bind with same mac address(dynamically)
Please give me the solution

Hi,
I Think you need to do Teaming on the servers.
++ configure etherchannel between switch and the server.
configuring etherchannel b/w 4503 and server:
================================
http://www.cisco.com/en/US/tech/tk389/tk213/technologies_configuration_example09186a008089a821.shtml
Sample NIC Teaming - HP NICs with Cisco Switches (EtherChannel) :
==============================================
http://support.citrix.com/article/CTX434260
There are several NIC teaming technologies available today from switch vendors. Cisco uses the term “EtherChannel.” Various switch vendors use various terms, and these may or may not provide the same exact functionality. Use of EtherChannel technology requires support from the server hardware vendor, NIC vendor, and Layer-2 switch vendor.
Hope this helps
Cheers
Somu
Rate helpful posts

Sometimes Local Address not in ARP table and Ping fails (network problem?)

I see something like this on our network a couple of times a week.
The same replies have been received from different hosts.
ping fails
local subnet machine is not in arp table
ping fails
local subnet machine is not in arp table
traceroute may or maynot succeed
If traceroute succeeds an entry is in the arp table
if traceroute fails no entry will be in the arp table.
A netstat -s, ont the local host, doesn't show any thing strange except that udpNoPorts=10844982 (Unfortunately I don't know what udpNoPorts is)
The remote host IS UP.
Does anyone have an idea as to why this is happening?
Can our 100mb network, which is not that busy, be loosing that many ICMP or ARP messages?
This is a problem because I'm the guy getting paged if a system is down.
Local host is Solaris 7 on same subnet at IP 168.173.8.8
Remote hosts are usually NT boxes.
/usr/sbin/ping -svR stpaul_web2 56 3
----stpaul_web2.agribank.com PING Statistics----
3 packets transmitted, 0 packets received, 100% packet loss
/usr/sbin/arp stpaul_web2
stpaul_web2 (168.173.8.143) -- no entry
/usr/sbin/ping -svR stpaul_web2 56 3
----stpaul_web2.agribank.com PING Statistics----
3 packets transmitted, 0 packets received, 100% packet loss
/usr/sbin/arp stpaul_web2
stpaul_web2 (168.173.8.143) -- no entry
/usr/sbin/traceroute stpaul_web2
1 stpaul_web2.AGRIBANK.COM (168.173.8.143) 2995.868 ms 0.231 ms 0.211 ms
/usr/sbin/arp stpaul_web2
stpaul_web2 (168.173.8.143) at 0:1:2:cc:a3:51
Any help is greatly appreciated.
Ks

Hi,
I Think you need to do Teaming on the servers.
++ configure etherchannel between switch and the server.
configuring etherchannel b/w 4503 and server:
================================
http://www.cisco.com/en/US/tech/tk389/tk213/technologies_configuration_example09186a008089a821.shtml
Sample NIC Teaming - HP NICs with Cisco Switches (EtherChannel) :
==============================================
http://support.citrix.com/article/CTX434260
There are several NIC teaming technologies available today from switch vendors. Cisco uses the term “EtherChannel.” Various switch vendors use various terms, and these may or may not provide the same exact functionality. Use of EtherChannel technology requires support from the server hardware vendor, NIC vendor, and Layer-2 switch vendor.
Hope this helps
Cheers
Somu
Rate helpful posts

ARP table not populating mac address for previously reachable IP address

Router has been online and working fine with one BGP neighbor for almost 2 years and no downtime. 2 weeks ago, added a 2nd BGP peer. Everything worked fine for 2 weeks, then all of a sudden yesterday the 2nd BGP peer is disconnected and does not come back. ISP checks and sees everything looks fine on their end. We cannot even ping each other now.
Upon investigation, the ARP table is not even populating the MAC address for the BGP peer IP anymore (same local subnet). Stays "incomplete" in the table no matter what we do, including clearing arp table, changing IP address, etc.
Plug a laptop directly into the 2nd BGP peer FE port and replicate the IP addressing. Laptop cannot ping Router, but Router CAN ping laptop. Check ARP table, but STILL no mac address assigned and now not even the ARP table showing "incomplete".
Thinking it could be the FE interface, switch to the 2nd FE interface and perform same laptop test, this time with arbitrary IP addressing. Now cannot ping each other, no MAC in ARP table.
End up rebooting the router and lo-and-behold, everything is working normally again. 2nd BGP peer peers up instantly.
I should also mention that the 1st BGP peer worked flawlessly throughout, taking all the Internet load and having no issues throughout.
Also, the FE ports for the 2nd BGP peer are on an HWIC FE card plugged into the router. The 1st BGP peer is plugged into the built-in GE interface. 2901 running: c2900-universalk9-mz.SPA.151-4.M4.bin
Lastly, no router resource issues, no error messages, no logs. Just the BGP peer disconnecting.
I have never, in 20 years working with Cisco routers seen something like this before. This is the most fundamental aspect of IP and Ethernet that was not working.
Has anyone ever seen this behavior before??
Here is the router config (IP's changed):
version 15.1
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
service internal
service sequence-numbers
boot-start-marker
boot-end-marker
logging buffered 150000
aaa new-model
aaa authentication login LAUTHEN local
aaa authentication login TAUTHEN local group tacacs+ enable
aaa authorization console
aaa authorization exec LAUTHOR local if-authenticated
aaa authorization exec TAUTHOR local group tacacs+ if-authenticated
aaa session-id common
clock timezone PST -8 0
clock summer-time PDT recurring
no ipv6 cef
no ip source-route
ip cef
no ip domain lookup
multilink bundle-name authenticated
username ubiadmin privilege 15 secret 4 .JbeuWXuZvchrG0OL.5BftFtqrrEyxcnVHn5rIuCnTk
username umitsnoc01 privilege 15 secret 4 cUmoRUjey9O1x.wk9S.kleX.iAAhCwihupr6Z98p6OA
redundancy
ip ssh version 2
track 1 interface GigabitEthernet0/0 line-protocol
class-map match-any AutoQoS-VoIP-RTP-Trust
match access-group name SIP-Media-INBOUND
class-map match-any AutoQoS-VoIP-Control-Trust
match ip dscp cs3
match ip dscp af31
class-map match-any Customer-Voice
match access-group name Customer-VPNs
class-map match-any media
match access-group name SIP-Media
class-map match-any signaling
match access-group name SIP-Signaling
policy-map AutoQoS-Policy-Trust
class AutoQoS-VoIP-RTP-Trust
priority percent 70
class AutoQoS-VoIP-Control-Trust
bandwidth percent 5
class class-default
fair-queue
policy-map queue
class signaling
bandwidth percent 5
class media
priority percent 50
class Customer-Voice
priority percent 40
class class-default
fair-queue
policy-map shape
class class-default
shape average 10000000
service-policy queue
interface Embedded-Service-Engine0/0
no ip address
shutdown
interface GigabitEthernet0/0
description BGP Peer 1
ip address 2.2.2.2 255.255.255.252
no ip redirects
ip flow ingress
ip flow egress
duplex auto
speed auto
service-policy output shape
interface GigabitEthernet0/1
description LAN
ip address 1.2.3.4 255.255.255.0
no ip redirects
ip flow ingress
ip flow egress
standby 255 ip 1.2.3.1
standby 255 priority 105
standby 255 preempt
standby 255 mac-address 1a2b.3c4d.5e6f
standby 255 track 1 decrement 10
duplex auto
speed auto
service-policy output AutoQoS-Policy-Trust
interface FastEthernet0/0/0
description BGP Peer 2
ip address 1.1.1.1 255.255.255.252
ip flow ingress
ip flow egress
duplex full
speed 100
service-policy output shape
interface FastEthernet0/0/1
no ip address
shutdown
duplex auto
speed auto
router bgp 7777
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 1.2.3.0 mask 255.255.255.0
neighbor 1.1.1.2 remote-as 5555
neighbor 1.1.1.2 update-source FastEthernet0/0/0
neighbor 1.1.1.2 prefix-list L3-DEFGW in
neighbor 1.1.1.2 route-map L3-LPREF-IN in
neighbor 2.2.2.1 remote-as 6666
neighbor 2.2.2.1 ebgp-multihop 2
neighbor 2.2.2.1 update-source GigabitEthernet0/0
neighbor 2.2.2.1 send-community
neighbor 2.2.2.1 prefix-list COLO-DEFGW in
neighbor 2.2.2.1 route-map COLO-LPREF-IN in
neighbor 2.2.2.1 route-map COLO-OUT out
ip forward-protocol nd
ip bgp-community new-format
ip as-path access-list 5 permit _5555_
ip as-path access-list 5 deny .*
ip as-path access-list 10 permit ^6666$
no ip http server
no ip http secure-server
ip flow-top-talkers
top 50
sort-by bytes
ip route 0.0.0.0 0.0.0.0 1.1.1.2 254 name L3
ip route 0.0.0.0 0.0.0.0 2.2.2.1 255 name COLO1
ip route 10.0.0.0 255.0.0.0 10.10.10.10 name FW_OUTSIDE
ip tacacs source-interface GigabitEthernet0/1
ip access-list standard SNMP_SOURCES
permit 12.12.12.0 0.0.0.255
deny any log
ip prefix-list L3-DEFGW seq 5 permit 0.0.0.0/0
ip prefix-list COLO-DEFGW seq 5 permit 0.0.0.0/0
ip prefix-list COLO-LPREF-OUT seq 5 permit 1.2.3.0/24
route-map COLO-LPREF-IN permit 5
match as-path 5
set local-preference 250
route-map COLO-LPREF-IN permit 10
set local-preference 150
route-map COLO-LPREF-IN permit 20
route-map COLO-OUT permit 10
match ip address prefix-list COLO-LPREF-OUT
set as-path prepend 7777 7777 7777
set community 29795:1004
route-map COLO-OUT permit 20
route-map L3-LPREF-IN permit 10
match as-path 10
set local-preference 200
route-map L3-LPREF-IN permit 20
set local-preference 150
snmp-server enable traps snmp authentication linkdown linkup coldstart warmstart
snmp-server enable traps vrrp
snmp-server enable traps flowmon
snmp-server enable traps transceiver all
snmp-server enable traps ds1
snmp-server enable traps call-home message-send-fail server-fail
snmp-server enable traps tty
snmp-server enable traps license
snmp-server enable traps envmon
snmp-server enable traps ethernet cfm cc mep-up mep-down cross-connect loop config
snmp-server enable traps ethernet cfm crosscheck mep-missing mep-unknown service-up
snmp-server enable traps flash insertion removal
snmp-server enable traps mac-notification
snmp-server enable traps aaa_server
snmp-server enable traps cef resource-failure peer-state-change peer-fib-state-change inconsistency
snmp-server enable traps memory bufferpeak
snmp-server enable traps config-copy
snmp-server enable traps config
snmp-server enable traps config-ctid
snmp-server enable traps event-manager
snmp-server enable traps hsrp
snmp-server enable traps cpu threshold
snmp-server enable traps rsvp
snmp-server enable traps syslog
snmp-server enable traps vtp
snmp-server enable traps ipsla

When you were checking the ARP table was there an entry for Fast0/0/0?
HTH
Rick

Strange Arp table

Hi
using solaris 10, I found that arp command output shows some confusing
entry..
for example: the MAC address of Gateway is not really the MAC what my cisco
gateway in reality has but the MAC shown in arp output is of NIC on a
windows 2003 server which is not supposed to be gateway or a router nor is
the 2003 machine configured for such routing/gateway services.
Could it be something wrong in solaris 10 ? or wrong in windows 2003 os or
hardware ? Solaris 10 is on sparc and windows 2003 is on a Dell power edge
1955..while actual gateway is cisco and working fine as per the network guys
but I am not sure..
any ideas ?
Thanks

Hello,
We are having similar issues. We are running T2000s and T5140s, Solaris 10 5/08, patched to the June 2008 EIS DVD, plus kernel patch 137111-06. Entries in these Sun servers' ARP tables are being overwritten.
server1# arp -a | grep server2
nxge0 server2.fubar.com 255.255.255.255 00:14:4f:46:6b:4e
server1# arp -a | grep server2
nxge0 server2.fubar.com 255.255.255.255 00:1e:c9:3a:16:c0
Those two arp -a commands were run a few minutes apart. The first one is server2's real MAC address. The second one is the MAC address of a Dell Windows server.
Sun Support says it's because as of Solaris 10 Update 4 (or kernel patch 120011-14), they are adhering more closely to RFC 826. Sun Support is blaming the Dell Windows servers with Broadcom ethernet cards on our network. Sun says that they need to be patched. See the following: http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&dl=false&l=en&s=gen&docid=49F4FB5AA612CFF6E040A68F5A28020D&doclang=en&cs
The problem is, our Windows support team is patching the Dell servers, but it is not fixing the problem.
We are escalating the problem within Sun, and are asking them for a workaround. It is all noble and good that Sun is adhering closely to RFC 826, but they must understand that by doing so, they are essentially making our Sun servers unusable.

3750G won't "age out" old arp table entries

WS-C3750G-24TS running
12.2(20)SE4, RELEASE SOFTWARE (fc1).
sho mac-address-table aging-time
Vlan Aging Time
253 300
252 300
254 300
255 300
1 300
251 300
The aging is not working. I can failover some devices I have and the mac-address of the old device associated the the IP never ages out. "Clear arp" makes the standby unit respond to pings and connectivity to the standby unit is 100% after the "clear arp".
Showing the arp cache, I can see the IP associated with the old mac-address and the "age" keeps increasing, not decreasing with the old mac-address.
It also doesn't matter if the Primary unit has been rebooted, switch keeps the old mac-address associated the Primary unit.
Suggestions?

I think permanent entry should have been made into the arp cache using the "arp ip-address hardware-address type" command.
To remove this arp entry, you can try "clear arp-cache".This will delete all dynamic entries from the ARP table.
for more details, refer the following page:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_command_reference_chapter09186a00800ca5b0.html#1017562

LMS 4.2 User tracking and router arp table

Hi,
If I have understand correctly, the IP address - mac address matching was made with the arp table of a cisco acces switch if it will made the L3.
My access switch wasn't used for L3 routing, only L2
It's possible to set user track to use the arp table of a firewall or a router for made this matching ?
Thanks a lot

As long as you have a supported Cisco Layer 3 device in your LMS-management domain, you should be able to correlate the IP-MAC addresses in User Tracking (UT).
UT support is not specifically listed for the ASA firewall - I'm not sure it will support that feature if it is the users' gateway.
Useful links:
UT explanation from the LMS Admin Guide
Supported devices listing
Hope this helps.

ARP Table Access using SNMP

Dear All,
In Cisco Switches and routers we can enable access to the ARP Table using SNMP by using the following commands:
no snmp-server view MibExcluded at excluded (Mac Address Table)
no snmp-server view MibExcluded ip.21 no excluded (Routing Table)
snmp-server view MibExcluded ip.22 excluded (ARP Table)
how i can enable the ASA/FWSM to allow access to the ARP Table using SNMP?
best Regards

The at and ipNetToMediaTable are not supported on the ASA or FWSM. There have been numerous requests for support, but I do not know of an ETA for these objects.
The bug ID for the enhancement request is CSCsq35214.

Sending Ciscowrks device credential Verification Job alters the device ARP table.

Hi:
I send a Device credential verification Job to two different devices , a Cisco 3750 and a blade switch WS-CBS3120. I configured SNMP write access to the switches. The SNMP write access in either SNMP v1 or SNMP V3 , tried both.
The job is send from the Ciscoworks server.
Once the job has completed, I do a show ip arp on the device and find a new entry with the IP address of the Ciscoworks Server and the mac-address of the L2 next hop.
We would not have noticed this behavior had it not been that in the case that the switch next hop is an HSRP vlan on a nexus , the ARP entry entered into the switch is incorrect, and from then on the switch loses connection to Ciscoworks.
The Mac-address that is entered by Ciscoworks , in the case of nexus is a statice mac defined on the Nexus for the Vlan in question , but it is NOT the HSRP default gateway MAC address. Therefore we lose connection between the switch and Ciscoworks. One has to manually clear the ARP table inorder to again reach the Ciscoworks.
Questions:
1. Why does Ciscoworks insist on changing the ARP table?
2. Is this ARP entry aged out or is it permeant as would an ARP entry which is entered through CLI be permeant ?
3. In the case of the Nexus connection, this ARP entry does not allow Ciscoworks and the device to communicate. This is not productive!
Has any one come across this situation ? Any known fixes, workarround? I was not able to find a word about this on Cisco's site.
Our Ciscoworks is at the following levels:
CW Common services    3.3.0
LMS portal                    1.2.0
CW Assistent                1.2.0
RME                             4.3.1
Device fault manager      3.2.0
IPM                              4.2.1
Cisco View                    6.1.9
campus Manager            5.2.1
thanks   for any help
Mickey

CiscoWorks does not change the ARP table, at least not overtly. A credential verification job will do the following things depending on what protocols are selected to test:
SNMP RO : Fetches sysLocation.0
SNMP RW : Sets sysLocation.0 to the value currently stored in sysLocation.0
Telnet : Logs in using DCR username and password
SSH : Logs in using DCR username and password
Enable : Enters enable mode and verifies privilege level 15
If one of these things are causing the ARP table to change, then there is something fishy in the device or network configuration. I've never heard of such behavior relating to CiscoWorks before.

ARP table clash with checkpoint and ASA firewal issue

We are migrating DMZ segments from a checkpoint to a ASA 5585 firewall that we had connected to the same segments as the Checkpoint except on different IP addresses then the checkpoint interfaces. The Checkpoint interfaces are the default gateway for the servers. When I implemented the NATs entries below we experienced an arp table clash with the checkpoint and ASA firewall on the local segments that caused a application outage. What was determined was that the checkpoint firewall was showing that all the IP addresses in particular on vlan130 segment was associating the MAC address of the ASA interface instead of the real sever MAC address. I need assistance understanding the reason why the Checkpoint was pointing the ARP entries for many different address on VLAN130 to the ASA firewall MAC?
nat (any,internet-outside) source static any any destination static isxh2007_Xlate_167.9.6.21 isxh2007_10.121.201.86 unidirectional description To match chkpt NAT rule #5
nat (VLAN130,internet-outside) source static ISX_EDI_Hosts isxh2008_Xlat_167.9.6.22 unidirectional
nat (any,internet-outside) source static Private-Addresses ISX_OUTBOUND_NAT_167.9.6.1 destination static external_167.9.x external_167.9.x unidirectional
nat (any,any) source static Mars-Internal-All Mars-Internal-All destination static Private-Addresses Private-Addresses
nat (internet-dmz,internet-outside) source static acs-vmww2419.mars-ad.net acs-vmww2419_xlate_167.9.6.23
nat (internet-dmz,internet-outside) source static acs_vmww2420 acs_vmww2420_xlate_167.9.6.24
nat (internet-dmz,internet-outside) source static pass_reset_internal_10.121.201.50 pass_reset_external_167.9.6.25
nat (internet-dmz,internet-outside) source static HE-Portal-poland_10.121.120.10 ext_HE-Portal-poland_167.9.6.26
nat (any,internet-outside) source dynamic any ISX_OUTBOUND_NAT_167.9.6.1
isxasa04/wwy-legacy# sho interface
Interface TenGigabitEthernet0/8.129 "core-inside", is down, line protocol is down
MAC address 442b.0330.aba2, MTU 1500
IP address 10.121.129.X, subnet mask 255.255.255.0
Traffic Statistics for "core-inside":
241633 packets input, 12094352 bytes
44788 packets output, 3032584 bytes
109732 packets dropped
Interface TenGigabitEthernet0/9.130 "VLAN130", is down, line protocol is down
MAC address 442b.0330.aba3, MTU 1500
IP address 10.121.130.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN130":
1264203 packets input, 136452168 bytes
326080 packets output, 69216516 bytes
794035 packets dropped
Interface TenGigabitEthernet0/9.136 "VLAN136", is down, line protocol is down
MAC address 442b.0330.aba3, MTU 1500
IP address 10.121.136.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN136":
374547 packets input, 23696109 bytes
51186 packets output, 3324895 bytes
173500 packets dropped
Interface GigabitEthernet0/1 "internet-outside", is down, line protocol is down
MAC address 442b.0330.ab9b, MTU 1500
IP address 167.9.6.X, subnet mask 255.255.255.0
Traffic Statistics for "internet-outside":
352158 packets input, 17245425 bytes
76888 packets output, 3872904 bytes
12255 packets dropped
Interface GigabitEthernet0/2 "internet-dmz", is down, line protocol is down
MAC address 442b.0330.ab9c, MTU 1500
IP address 10.121.201.X, subnet mask 255.255.255.0
Traffic Statistics for "internet-dmz":
237795 packets input, 12460108 bytes
40787 packets output, 2775684 bytes
27378 packets dropped
Interface GigabitEthernet0/4 "VLAN140", is down, line protocol is down
MAC address 442b.0330.ab9e, MTU 1500
IP address 10.121.140.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN140":
386931 packets input, 18807725 bytes
48936 packets output, 3319712 bytes
114417 packets dropped
We crosschecked MAC addresses and this is what we found:
Checkpoint ARP table:
10.121.130.101 44:2b:3:30:ab:a3 3285
ASA ARP table:
isxasa04/wwy-legacy# sh arp | i 10.121.130.101
VLAN130 10.121.130.101 001a.4b06.dd45 10525
Server real address provided by processing:
0x001A4B06DD45
When we saw that the Checkpoints had a different/wrong entry we shut down all the physical ports on the new ASAs (except for failover and management);
Kevin cleared the ARP table on the Checkpoints and problem was solved;
Later I saw this:
isxasa04# sh int | i MAC
MAC address 442b.0330.ab9a, MTU not set
MAC address 442b.0330.ab9b, MTU not set
MAC address 442b.0330.ab9c, MTU not set
MAC address 442b.0330.ab9d, MTU 1500
MAC address 442b.0330.ab9e, MTU not set
MAC address 442b.0330.ab9f, MTU not set
MAC address 442b.0330.aba0, MTU not set
MAC address 442b.0330.aba1, MTU not set
MAC address 442b.0330.ab98, MTU not set
MAC address 442b.0330.ab99, MTU not set
MAC address 442b.0330.aba2, MTU not set
MAC address 442b.0330.aba3, MTU not set

The Asa is proxy Arping those macs. Turn off proxy arp and put in static arp entries until you completely shut down the checkpoint.
Sent from Cisco Technical Support iPad App

Verizon 9100EM Router - ARP Table No Longer Working

I have the Westell 9100EM router from Verizon. The router allows to set static DHCP connections using a function called ARP Table (under Advanced menu). It actually used to work. However, when I attempted to add a new static connection today, ARP Tbale was no longer working. It shows connections that I set up in the past but does not allow to add any new connection or even to change anything.
Specifically, the ARP Table now has only three columns (IP Address, Physical Address, and Device). There used to be several additional columns (Lease Type, Connection Name, Status, and Action), which are now gone. The "Action" column had links from where one could change the setting. It also had the option "New Static Connection", which is now gone as well.
Any idea what the reason could be?
Thanks a lot.

It seems to me that the router's firmware (OS if you will) was upgraded OR downgraged.
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LAN - ARP Table

Hello,
I'm not sure if someone has come across this before. But they might enlighten me.
Under what circumstances would you see ARP enteries on a switch for subnets out side of the local subnet?
Example 2 switches back to back everything in default vlan 1. These uplink to a pair of routers running HSRP.
I would expect to see x.x.x.200 /24
arp enteries for devices on the switches
but not addresses outside of this range.
Any input appreciated.
Thank you.

Suppose you are talking layer2 switches like the 2950 series?
First of all, this has nothing to do with the switching process on the access ports. The arp table on a switch is only used for the IP management interface. ARP entries will appear for anything that you contact from the console.
Typically anything beyond your local subnet is covered by a default gateway but when the switch is using proxy-arp for address resolution you can see anything on your network.
Regards,
Leo

Delete ARP table entry

I need to create a program to delete an entry in the ARP table in Windows 7 with LabVIEW or TestStand. The test that I am developing communicates with the DUT over Ethernet. Each DUT has the same IP address to start but different MAC addresses. I am noticing that there can be long delays in the test execution when trying to connect and deleting the previous entry in the ARP table seems to help. But currently I have to do this manually through the command line. The command "arp -d" requires elevated privileges. I have been having a tough time getting LabVIEW to elevate the system exec. Does anybody have an ideas? Is there any .NET access to the ARP table?
Thanks,
Paul
Solved!
Go to Solution.

I would try looking into tuning the ARP timing parameters in Windows.
We suffered from various TCP performance/connection problems some years ago and our solution was to modify the the default number of TCP sockets and timeouts (we were experiencing port exhaustion). The tweeks eliminated most of our problems, no LV/TS code changes required.
I tried to find info on ARP settings for Windows 7, but it seems that there is much less info available than ther is for XP.
The registry keywords most common for older versions of Windows were "ArpCacheLife" and "ArpCacheMinReferencedLife"
EDIT:
These settings were apparently removed in Vista. I found this on the M$ site; they may apply to later versions as well since M$ is following an RFC for ARP management...
http://support.microsoft.com/kb/949589
Now is the right time to use %^<%Y-%m-%dT%H:%M:%S%3uZ>T
If you don't hate time zones, you're not a real programmer.
"You are what you don't automate"
Inplaceness is synonymous with insidiousness

Gratuitous ARPs do not populate the router ARP Table

Hello,
In order to debug an ARP problem in a Firewall cluster environment, I connected a one-armed router on the public VLAN of the firewall cluster, in order to observe the ARP cache behaviour during a switchover. I configured a loopback interface on this router and a default route to this loopback interface to simulate a real router.
When a switchover occurs between firewall cluster members, the active member sends Gratuitous ARPs for all NATed IP addresses. In my environment, I have 110 NATed addresses configured on the firewall.
By launching a "debug arp" on the one armed router, I clearly see all 110 gratuitous ARPs arriving on the router, but the ARP cache of the router is NOT populated with the 110 entries...
Note : The command is configured on the one armed router :
Router(config)# ip arp gratuitous local
What can be the problem ? Is there any condition for a router to accept Gratuitous ARPs ?
Thank you for any help
Yves

Hi
Gratuitous arp is used when a host wants to inform the switch that the mac-address has changed eg.
You have a cluster which has redundant connections and an IP to mac-address mapping. If the active NIC fails the IP address is moved across to the standby NIC but the standby NIC has a different mac-address. So the cluster sends out a gratuitous arp which informs the switch of the new IP to mac-address mapping.
The reason you might not want to allow gratuitous arp is that you might not want your switch updating it's arp table based on annoucements from devices on the LAN as you could very easily spoof mac-addresses and corrupt the arp cache.
HTH
Jon

MAC-to-IP address ARP table?

The SNMP MIB entry ipNetToMediaPhysAddress gives the MAC address from the ARP table, referenced by the IP. Is there a table available anywhere in some router MIB that would give the equivalent of "MediaPhysAddressToipNet" (reverse) information so that an IP address in the ARP table could be referenced using the MAC address?
RFC1213 section 3.6 alludes to a future document that would define a MIB for CLNP and it would contain two tables for mappings in both directions. But I've not been able to find anything else about that.
I'm trying to avoid pulling the entire ARP table from the router (several thousand entries makes it take about 90 seconds and it drives the CPU to 100%) just to get a single MAC-to-IP address mapping when that info is needed.
--Scott

I haven't run across any such object, and a quick check of my 15.0 router yields nothing I missed.
You might consider doing periodic collection of the ARP table (e.g. when most users are logged into the network) to have a cache through which to search for this kind of information. This is how the Campus Manager User Tracking application works. By default, it polls the ARP table (along with swithc MAC/CAM tables) at 10:00 and 14:00 to build a table of all connected users. From this one can search for IPs, MACs, and even usernames.

Cisco EA4500 ARP Table?

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