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- About Sherif Atef Ahmed Ismail
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Member since
11-15-2011
182
Posts
25
Helpful
1
Solution
Created by
Sherif Atef Ahmed Ismail
in XR OS and Platforms
in XR OS and Platforms
07-05-2015
10:58 PM
07-05-2015
10:58 PM
Big congratulations dear :)
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02-03-2015
05:06 AM
Dears Does ES+ cards supported If SUP-2T is installed on 7600 routers ? Many Thanks
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Hi AshirkarMany thanks for
in Service Providers Documents
12-09-2014
01:56 PM
12-09-2014
01:56 PM
Hi Ashirkar Many thanks for your great document I know you have written it long time ago but I just have a quick question please In this design there is no need to have a BGP session between both RRs , right ? I believe only reason it may be present in case RRs become also PEs in future What do you think ? Many Thanks Regards Sherif Ismail
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11-19-2014
07:57 AM
Dear Ciollaro Lets say I am having 2 VRFs on router R1 ; vrf orange and vrf green . vrf orange is importing RT 1:1 from MP-BGP/MPLS that includes among many prefix 10.0.0.0/24 . Now there are users in vrf green who want to access servers within same prefix however restriction that you should not do use import/export nor do changes in remote side thats why I was thinking of Juniper command "next-table" Thanks Regards Sherif Ismail
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11-04-2014
09:24 AM
Dears Thanks for your reply/assistance @ Enrico Unfortunately I can't use this as next-hop interface is the MPLS interface so actually no next-hop IP @ Paul This would be possible from remote side. Bad news I have no access to it I did a workaround for this issue but its not the best solution. Thanks Regards Sherif Ismail
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11-01-2014
07:29 AM
One thing that is still a myth for me why we didn't encounter any unicast flooding on standby HSRP router. My understanding is that when flooded traffic reaches R2 (standby router) it should also be flooded , right ? Many thanks in advance Regards Sherif Ismail
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11-01-2014
07:21 AM
Hi Inayath Many thanks .. You are a network saver :) This may explains the myth of unicast flooding we had in our network. According to documentation this behavior should only occur If we are having asymmetric routing or HSRP with load-balancing. In our case we had HSRP routers where all active groups were in one router so theoretically we should not have unicast flooding especially that we are having one DFC ES+ card and no ports connected to RSP ports. But now my guess (thanks to your replies) this happened cause SVI interfaces are part of PFC so flooding will occur between DFC & L3 SVIs @ PFC. So in our case either "mac-address-table synchronize" or adjusting CAM to be equal that of ARP would have solved the issue. I have applied the 2nd one cause was still studying the effect of "mac-address-table synchronize" Hope my analysis is correct :) Once again many thanks
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10-31-2014
07:18 AM
Dears Many thanks for your replies Sorry i didnt see first reply probably a problem in mobile update. 1- One last thing please would there be any router memory worries if i configured this command as now CAM table for whole modules will be synced. 2- As I understand if this command is not configured unicast flooding will occur thus links with low bandwidth may be affected, right ? Many thanks for your assistance Regards Sherif Ismsil
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10-30-2014
07:10 AM
Hi Mostafa Many thanks for your deep analysis answer :) I got it. So the issue is actually with the router who is doing the L3 routing. If both PCs GWs are one same router then no issues however If they are on different router then it would cause this unicast flooding issue. Makes perfect sense What I still cant figure it out is that in our network we had below behavior 2 HSRP routers where all groups were active on one router Unicast flooding only occured on the active HSRP router. No issues reported on 2nd standby HSRP router !! Once I increased CAM table to be equal or more than that of ARP, traffic decreased from 150 Mbps to 4 Mbps Still sometimes we encounter some peaks that may reach to 23 Mbps Questions Why we faced this issue on 1st router only as R2 should also flood this traffic ? Why we sometimes have peaks since we are not have in changes in STP ? Why fix solved the issue when we should not have this behavior from beginning ? BTW, as you are an expert in LAN issues, may you have a look please on below thread :) https://supportforums.cisco.com/discussion/12338861/mac-address-table-synchronize Many Thanks for your support Regards Sherif Ismail
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Created by
Sherif Atef Ahmed Ismail
in Switching
in Switching
10-28-2014
11:48 PM
10-28-2014
11:48 PM
Dears Would like your assistance please in understanding unicast flooding behavior According to below URLs it should only occurs If we are having HSRP load-balancing between both routers or asymmetric routing. http://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/10583-62.html#t8 http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6000-series-switches/23563-143.html Explanation makes sense however whats confuses me that even if we are using single router or HSRP where all all active groups are on one router still this behavior should occur. According to my understanding is that when packet is L3 switched from one VLAN to another source MAC is lost that's why it erased from CAM table after CAM age timer. So this behavior should occur in all cases , right ? Regards Many Thanks Sherif Ismail
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10-28-2014
11:46 PM
Dears Would like your assistance please regarding command "mac-address-table synchronize" My understanding is that it syncs CAM table between different DFCs & RSP PFC So If we are having only one DFC there would be no need for this command. It will only be useful in case we are having several DFCs or there is a communication between DFC and ports connected in RSP. 1- Correct ? 2- Is SVI interface considered to be part of DFC or PFC ? I am asking this cause if part of PFC then this command would be needed Many Thanks Regards Sherif Ismail
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Created by
Sherif Atef Ahmed Ismail
in XR OS and Platforms
in XR OS and Platforms
10-28-2014
07:47 AM
10-28-2014
07:47 AM
Hello Yes this is a known issue. It is related to PDU MTUs You can try to change clns mtu or disable hello padding http://certcollection.org/forum/topic/241895-xr-neighborship-with-r8-and-r9-issue/ Thanks Sherif Ismail
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Created by
Sherif Atef Ahmed Ismail
in Routing
in Routing
09-15-2014
03:40 AM
09-15-2014
03:40 AM
Dears Would like your assistance please regarding below Is there a similar command to JUNOS "next-table" in Cisco ? Would like to do MPLS VPN route leaking between 2 vrfs. route-targets can not be used as I am only receiving default route so leaking default route is never a good idea. Problem I can't use static route as there is no next-hop/interface being an MPLS network What I wish is to define specific static routes and tell router to search in a different VRF for the next-hop/interface. From what I can see is that leaking with static route can only be done by specifying an interface that is in a different vrf ;i.e ip route vrf blue x.x.x.x 255.255.255.255 fa0/1 10.0.0.0.2 interface fa0/1 ip vrf forwarding green ip address 10.0.0.1 255.255.255.0 What I wish to do ip route vrf blue x.x.x.x/24 next-table orange Any ideas ? Thanks
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Created by
Sherif Atef Ahmed Ismail
in Service Providers Documents
12-09-2014
12-09-2014
Hi AshirkarMany thanks for your great document I know you have written
it long time ago but I just h...
11-19-2014
Dear CiollaroLets say I am having 2 VRFs on router R1 ; vrf orange and
vrf green.vrf orange is impor...
11-04-2014
DearsThanks for your reply/assistance @ EnricoUnfortunately I can't use
this as next-hop interface i...
11-01-2014
One thing that is still a myth for me why we didn't encounter any
unicast flooding on standby HSRP r...
11-01-2014
Hi InayathMany thanks .. You are a network saver :)This may explains the
myth of unicast flooding we...
10-31-2014
DearsMany thanks for your repliesSorry i didnt see first reply probably
a problem in mobile update. ...
10-30-2014
Hi MostafaMany thanks for your deep analysis answer :)I got it. So the
issue is actually with the ro...
Created by
Sherif Atef Ahmed Ismail
in Switching
10-28-2014
10-28-2014
DearsWould like your assistance please in understanding unicast flooding
behaviorAccording to below ...
10-28-2014
DearsWould like your assistance please regarding command
"mac-address-table synchronize"My understan...
10-28-2014
HelloYes this is a known issue. It is related to PDU MTUsYou can try to
change clns mtu or disable h...
Created by
Sherif Atef Ahmed Ismail
in Routing
09-15-2014
09-15-2014
DearsWould like your assistance please regarding belowIs there a similar
command to JUNOS "next-tabl...
Public Statistics
| Date Registered | 11-15-2011 04:10 PM |
| Date Last Visited | 10-09-2017 12:31 PM |
| Total Messages Posted | 182 |
| Total Helpful Votes Received | 25 |
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