Refer to the exhibit. Which BGP attribute should be manipulated to have CE1 use PE1 as the primary path to the internet?
Refer to the exhibit. Which BGP attribute should be manipulated to have CE1 use PE1 as the primary path to the internet?
The weight attribute should be manipulated on PE1 on outbound routes advertised to CE1, as weight is a BGP attribute specific to Cisco routers and is used to prefer one path over another. By setting a higher weight on PE1, it becomes the preferred route for CE1. Weight is not communicated to other routers and is only relevant to the local router that receives the BGP update.
A- this would work if routers in same AS since LP is passed in iBGP B- this might work C- MED defaults to 0 so changing only CE1-PE1 would not do the work D- Weight is locally significicant, so NO
The issue with C is that, MED defaults to Zero. Thus how can you manipulate on CE-PE1 inbound... you would need to increase med on CE-PE2 inbound for this to work. Seems like B will be the only working solution based on the available info we have.
A is correct. Lower LP from PE2 will definatly force traffic from CE1 towards PE1. C is not complete; we have to manipulate MED from both PEs not only from one; default is MED =0; how to beat this if only manipulating MED for routes from PE1?
A - Local Preference is not attached to eBGP updates and it only stays within the AS (iBGP) so UNLESS the routers are all in the same AS it's not going to help here. B - if we modify the origin of ALL routes on each router inbound and outbound we can make the path to PE1 preferred. This is definitely a possible but horrible option. C - The MED attribute is 0 by default so modifying it on inbound routes from PE1 can not make it preferred D - the weight is only local to PE1, not advertised to CE1 I think the answer is actually B?
Yes, B. Horrible solution but only this will work.
C seems correct If we consider that PE1 and PE2 belongs to the same AS
Can't be A or D for obvious reasons. C might be excluded because by default the MED is 0 or does not exist (if does not exist is it considered as 0 by default). 0 is the most preferred, so a better MED than 0 can't be configured.
This is the only router the customer has access to.
Answer A: the local preference defaults to 100. Higher local preferences are preferred. If you set the local preference on PE2 to a lower value, then PE1 will be preferred by CE1 as the primary exit path. Answer B? A horrible idea. origin can be set with route maps, but thats not the intended purpose. Origin should be left alone. Answer C: incorrect. Setting MED on the inbound routes at PE1 has no effect on incoming traffic. you would have to set lower MED on the outbound prefixes to allow the Provider to prefer PE1... and that is ONLY IF both PE1 and PE2 connect to the same provider. you would also have to set a higher med on PE2 so that PE1 is preferred. -None of the answers are a good solution because asymmetric routing can still occur. but the question asks for a preffered path "TO the internet", so that means outbound traffic. I'll stick with answer A. Thoughts?
Restating my first sentence. Answer A: the local preference defaults to 100. Higher local preferences is preferred. On CE1 if you set a high local preference of inbound routes from PE1, then outbound traffic will be preferred to PE1. sticking with A on the chance that thas what they meant.
Answer B
I just noticed ccie_race went for C "If we consider that PE1 and PE2 belongs to the same AS" but I wonder if the choices changed, it sound like he is talking about the A for local preference. If they are all on the same AS that will work. Otherwise, I think it is option B to modify the Origin
i confirm C is correct