11-16-2011 10:05 PM - edited 03-07-2019 03:26 AM
I need some troubshooting help to solve this issue. We have 2 managed routers "A" and "B"across the service privder's VLAN network. The set up is like this->
Router A---VLAN "X"--> ISP ATM Switch A<----->ISP ATM Backbone<-----> ISP ATM Switch B<--VLAN "X"---Router B
We are able to ping from Router A to Router B on VLAN X with few drops but can't ping the other way around at all. The rest of the VLANs(there is 1 more) on the same trunk which is working just fine. So we opened an investigation with ISP to check for specefic VLAN having issue. The ISP claims that they are able to ping from their ATM switch A to our Router B with no drops but can't ping our Router "A" IP address. But if they do ping the broadcast IP they get response from Routers A and B both which kinda puzzles me as why would Router A will respond to broadcast IP if it does not respond to its IP ? Any ideas , please help..Thanks!
11-20-2011 11:21 AM
Hi,
Can you show at least the interface configs for both routers A & B
Regards
Alex
11-20-2011 01:37 PM
Hi acampbell,
I have pasted the int configs for both routers A and B respectively below. Any help will be appreciated in diagnosing this issue as ISP now wants to install a switch in front of our routerA and put sniffer on it for diagnostics. This will have a 15 min. downtime on all our VLANS on RouterA which are catering multiple sites on this trunk (as this is a primary hub router) with few sites having no back up at all
Thanks for your help!
RouterA#sh int gigabitEthernet 0/0.209
GigabitEthernet0/0.209 is up, line protocol is up
Hardware is Pinnacle GE, address is 001a.6ccd.0300 (bia 001a.6ccd.0300)
Description: --- To RouterB
Internet address is x.x.x.145/28
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 6/255, rxload 4/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 209.
ARP type: ARPA, ARP Timeout 04:00:00
Keepalive set (10 sec)
Last clearing of "show interface" counters never
RouterA#sh ip int gigabitEthernet 0/0.209
GigabitEthernet0/0.209 is up, line protocol is up
Internet address is x.x.x.145/28
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP Flow switching is disabled
IP CEF switching is enabled
IP CEF switching turbo vector
IP CEF turbo switching turbo vector
VPN Routing/Forwarding "znet"
IP multicast fast switching is enabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, CEF
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is disabled
TCP/IP header compression is disabled
RTP/IP header compression is disabled
Probe proxy name replies are disabled
Policy routing is disabled
Network address translation is disabled
WCCP Redirect outbound is disabled
WCCP Redirect inbound is disabled
WCCP Redirect exclude is disabled
BGP Policy Mapping is disabled
RouterA#
RouterB#sh int fastEthernet 0/0.209
FastEthernet0/0.209 is up, line protocol is up
Hardware is MV96340 Ethernet, address is 001f.9e17.8218 (bia 001f.9e17.8218)
Description: --- To RouterA
Internet address is x.x.x.146/28
MTU 1500 bytes, BW 10000 Kbit/sec, DLY 1000 usec,
reliability 255/255, txload 7/255, rxload 12/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 209.
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of "show interface" counters never
RouterB#sh ip int fastEthernet 0/0.209
FastEthernet0/0.209 is up, line protocol is up
Internet address is x.x.x.146/28
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP fast switching on the same interface is enabled
IP Flow switching is enabled
IP CEF switching is enabled
IP CEF VPN Flow Fast switching turbo vector
VPN Routing/Forwarding "znet"
IP multicast fast switching is enabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, Flow cache, CEF, Subint Flow
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is disabled
TCP/IP header compression is disabled
RTP/IP header compression is disabled
Policy routing is disabled
Network address translation is disabled
BGP Policy Mapping is disabled
WCCP Redirect outbound is disabled
WCCP Redirect inbound is disabled
WCCP Redirect exclude is disabled
RouterB#
11-21-2011 01:31 AM
These look OK to me.
What about the switch ports the routers are connected to.
Router A x.x.x.145/255.255.255.240 Encap Dot1Q 209
Router B x.x.x.146/255.255.255.240 Encap Dot1Q 209
Subnet x..x.x.144/255.255.255.240
Regards
Alex
11-21-2011 08:51 PM
I have no access to Switch as its service provider side on both ends(A & B)
11-21-2011 02:24 AM
Hi Nitin,
You said, you get response when pinged to broadcast ip,
is the ip they ping is x.x.x.159 or which ip ???
11-21-2011 08:55 PM
Hi Manju- Yes, when they ping x.x.x.159 from their switch, they get response from both .145(RouterA) and .146(Router B) But when pinged from RouterA to RouterB, we have 60-80% success and no response when pinged from RouterB to RouterA.
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