Re: [j-nsp] proxy arp C vs J
On Wednesday, February 08, 2012 08:10:59 AM Gordon Smith wrote: > Proxy ARP can be useful while sorting out a broken > (misconfigured) network, but can also cause you a lot of > grief. > If the network is configured correctly, it's just a > hindrance. Most definitely turn it off, then fix any > routing issues it was masking. That and ICMP Redirects. Mark. signature.asc Description: This is a digitally signed message part. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
Proxy ARP can be useful while sorting out a broken (misconfigured) network, but can also cause you a lot of grief. If the network is configured correctly, it's just a hindrance. Most definitely turn it off, then fix any routing issues it was masking. I see someone mentioned turning off gratuitous arps, but I'd only do that if really necessary, as its very useful for forcing a refresh of an entry e.g. E-Series cable customers Cheers, Gordon -Original Message- From: juniper-nsp-boun...@puck.nether.net [mailto:juniper-nsp-boun...@puck.nether.net] On Behalf Of biwa net Sent: Tuesday, 7 February 2012 5:57 a.m. To: juniper-nsp@puck.nether.net Subject: [j-nsp] proxy arp C vs J Hi Guys We are experiencing some issues in one of our client sites, Basically we migrate from a Cisco to a Juniper MX80, and since there has been some issues, mainly we are seeing IP addresses being shared by 2-3 mac address, to be precise , mac address being rewritten , ie: one IP is being seen on the Juniper owned by 3 different mac address within one hour ( the 1st mac address is being re-writen by the 2nd one and then 2nd by the 3rd mac). This is causing a lot of users not having any kind of internet connectivity.When we rollback to the Cisco device , this issue does not occur. After investigation we can safely eliminates the DHCP server being the cause of issue (, also proved when Cisco is roll back in the topology), The config of the Cisco is fairly simple and is almost 99.99% than the one being copied over to the Juniper. One thing we notice is that both Cisco and Juniper has proxy-arp configured on some of the interface, and we are planning in our next maintenance to disable it. my question is: is the proxy-arp behavior in Juniper slightly different than the Cisco ? thanks for your inputs ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
On Tue, Feb 7, 2012 at 2:23 AM, Alex Arseniev wrote: > Did you check what MACs are used in 1st, 2nd and 3rd time? Specifically MAC > OUIs. > I suspect this is a side effect of having C-J in the same broadcast domain. > Basically, when J-interface ARPs for a connected host, _AND_ if C has a > specific route to that host/32, the C will answer with own MAC. And potentially, depending on the configuration, the Cisco may try and proxy based on a route learned from the Juniper, creating a loop. The question I would ask: what is proxy arp used for? why? Cheers, jof ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
Did you check what MACs are used in 1st, 2nd and 3rd time? Specifically MAC OUIs. I suspect this is a side effect of having C-J in the same broadcast domain. Basically, when J-interface ARPs for a connected host, _AND_ if C has a specific route to that host/32, the C will answer with own MAC. I have seen this myself many times and I suggest to disable proxy-arp on C to get rid of this behavior. HTH Thanks Alex - Original Message - From: "biwa net" To: Sent: Monday, February 06, 2012 7:57 PM Subject: Re: [j-nsp] proxy arp C vs J Forgot to add we are running MX80 on Junos 11.2 On 6 February 2012 19:56, biwa net wrote: Hi Guys We are experiencing some issues in one of our client sites, Basically we migrate from a Cisco to a Juniper MX80, and since there has been some issues, mainly we are seeing IP addresses being shared by 2-3 mac address, to be precise , mac address being rewritten , ie: one IP is being seen on the Juniper owned by 3 different mac address within one hour ( the 1st mac address is being re-writen by the 2nd one and then 2nd by the 3rd mac). This is causing a lot of users not having any kind of internet connectivity.When we rollback to the Cisco device , this issue does not occur. After investigation we can safely eliminates the DHCP server being the cause of issue (, also proved when Cisco is roll back in the topology), The config of the Cisco is fairly simple and is almost 99.99% than the one being copied over to the Juniper. One thing we notice is that both Cisco and Juniper has proxy-arp configured on some of the interface, and we are planning in our next maintenance to disable it. my question is: is the proxy-arp behavior in Juniper slightly different than the Cisco ? thanks for your inputs ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
On Tuesday, February 07, 2012 03:57:55 AM biwa net wrote: > Forgot to add we are running MX80 on Junos 11.2 Can you send a sample topology and your interface configurations for the Cisco and Juniper routers? Mark. signature.asc Description: This is a digitally signed message part. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
Try the command: no-gratuitous-arp-request > > Basically we migrate from a Cisco to a Juniper MX80, and since there > > has been some issues, mainly we are seeing IP addresses being shared > > by 2-3 mac address, to be precise , mac address being rewritten , ie: > > one IP is being seen on the Juniper owned by 3 different mac address > > within one hour ( the 1st mac address is being re-writen by the 2nd > > one and then 2nd by the 3rd mac). ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] proxy arp C vs J
Forgot to add we are running MX80 on Junos 11.2 On 6 February 2012 19:56, biwa net wrote: > Hi Guys > We are experiencing some issues in one of our client sites, > > Basically we migrate from a Cisco to a Juniper MX80, and since there has > been some issues, mainly we are seeing IP addresses being shared by 2-3 > mac address, to be precise , mac address being rewritten , ie: one IP is > being seen on the Juniper owned by 3 different mac address within one hour > ( the 1st mac address is being re-writen by the 2nd one and then 2nd by > the 3rd mac). > > This is causing a lot of users not having any kind of internet > connectivity.When we rollback to the Cisco device , this issue does not > occur. > > After investigation we can safely eliminates the DHCP server being the > cause of issue (, also proved when Cisco is roll back in the topology), > > The config of the Cisco is fairly simple and is almost 99.99% than the one > being copied over to the Juniper. > > One thing we notice is that both Cisco and Juniper has proxy-arp > configured on some of the interface, and we are planning in our next > maintenance to disable it. > > my question is: is the proxy-arp behavior in Juniper slightly different > than the Cisco ? > > thanks for your inputs > ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
[j-nsp] proxy arp C vs J
Hi Guys We are experiencing some issues in one of our client sites, Basically we migrate from a Cisco to a Juniper MX80, and since there has been some issues, mainly we are seeing IP addresses being shared by 2-3 mac address, to be precise , mac address being rewritten , ie: one IP is being seen on the Juniper owned by 3 different mac address within one hour ( the 1st mac address is being re-writen by the 2nd one and then 2nd by the 3rd mac). This is causing a lot of users not having any kind of internet connectivity.When we rollback to the Cisco device , this issue does not occur. After investigation we can safely eliminates the DHCP server being the cause of issue (, also proved when Cisco is roll back in the topology), The config of the Cisco is fairly simple and is almost 99.99% than the one being copied over to the Juniper. One thing we notice is that both Cisco and Juniper has proxy-arp configured on some of the interface, and we are planning in our next maintenance to disable it. my question is: is the proxy-arp behavior in Juniper slightly different than the Cisco ? thanks for your inputs ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
